Access profile

Given the multidisciplinary nature of the scientific field of the programme, there are a wide range of degrees that qualify applicants for admission. The applicants considered most suitable for admission to the doctoral programme in Materials Science and Engineering are bachelor’s degree holders with a scientific and technological background who have completed a master's degree in Materials Science and Advanced Materials Engineering or a related field.

In addition to having suitable academic qualifications, it is considered important that applicants have certain personal characteristics – namely, an interest in the research projects carried out within the framework of the programme; critical and analytical skills; initiative, perseverance and persistence in their academic work; the ability to work in a team; and the ability to communicate effectively in English, both orally and in writing.

The main entrance qualifications for the programme are as follows:

Bachelor’s degree in Engineering or higher engineering degree (Industrial, Materials or Chemical Engineering) or a pre-EHEA degree in Physical and/or Chemical Sciences with a master’s degree in Materials Science and Engineering (or proof of having completed 60 ECTS credits of this master’s degree), or another master’s degree with the same content, from any higher education institution in the EHEA, or a non-EHEA country if the applicant is eligible for admission to doctoral studies in that country.

Students with the following qualifications are eligible for direct admission:

Bachelor’s degree in Engineering (Industrial, Materials, Chemical or similar) or a pre-EHEA degree in Physics and/or Chemistry with a master’s degree in Materials Science and Engineering.

With bridging courses:

Holders of a bachelor’s degree in Engineering (Industrial, Materials, Chemical or similar) or a pre-EHEA degree in Physics and/or Chemistry who have completed a master's degree in a field other than Materials Science and Engineering. If admitted, these students will be required to take bridging courses carrying up to 60 ECTS credits (subjects of the master’s degree that they have not taken).

Output profile

Doctoral candidates who complete a doctoral degree will have acquired the following competencies, which are needed to carry out quality research (Royal Decree 99/2011, of 28 January, which regulates official doctoral studies):

a) A systematic understanding of the field of study and a mastery of the research skills and methods related to the field.
b) An ability to conceive, design or create, put into practice and adopt a substantial process of research or creation.
c) An ability to contribute to pushing back the frontiers of knowledge through original research.
d) A capacity for critical analysis and an ability to assess and summarise new and complex ideas.
e) An ability to communicate with the academic and scientific community and with society in general as regards their fields of knowledge in the manner and languages that are typical of the international scientific community to which they belong.
f) An ability to foster scientific, technological, social, artistic and cultural progress in academic and professional contexts within a knowledge-based society.

The award of a doctoral degree must equip the graduate for work in a variety of settings, especially those requiring creativity and innovation. Doctoral graduates must have at least acquired the personal skills needed to:

a) Develop in contexts in which there is little specific information.
b) Find the key questions that must be answered to solve a complex problem.
c) Design, create, develop and undertake original, innovative projects in their field.
d) Work as part of a team and independently in an international or multidisciplinary context.
e) Integrate knowledge, deal with complexity and make judgements with limited information.
f) Offer criticism on and intellectually defend solutions.

Number of places

15

Duration of studies and dedication regime

Duration
The maximum period of study for full-time doctoral studies is three years, counted from the date of admission to the programme to the date of submission of the doctoral thesis. The academic committee of the doctoral programme may authorise a doctoral candidate to pursue doctoral studies on a part-time basis. In this case, the maximum period of study is five years, counting from the date of admission to the programme to the date of submission of the doctoral thesis. For calculating these periods, the date of admission is considered to be the date of the first enrolment for tutorials, and the date of submission the moment in which the Doctoral School officially deposits the doctoral thesis.

For full-time doctoral candidates, the minimum period of study is two years, counted from the date of an applicant's admission to the programme until the date on which the doctoral thesis is deposited; for part-time doctoral candidates it is four years. When there are justified grounds for doing so, and the thesis supervisor and academic tutor have given their authorisation, doctoral candidates may request that the academic committee of their doctoral programme exempt them from the minimum period of study requirement.

The calculation of periods of study will not include periods of absence due to illness, pregnancy or any other reason provided for in the regulations in force. Students who find themselves in any of these circumstances must notify the academic committee of the doctoral programme, which, where appropriate, must inform the Doctoral School. Doctoral candidates may also temporarily withdraw from the programme for up to one year, and this period may be extended for an additional year. Doctoral candidates who wish to interrupt their studies must submit a justified request to the academic committee of the doctoral programme, which will decide whether or not to approve the request. Each programme will establish conditions for readmission to doctoral studies.

Extension
If full-time doctoral candidates have not applied to deposit their thesis by the end of the three-year period of study, the academic committee of the programme may authorise an extension of up to one year. In exceptional circumstances, a further one-year extension may be granted, subject to the conditions established by the corresponding doctoral programme. In the case of part-time doctoral candidates, an extension of two years may be authorised. In both cases, in exceptional circumstances a further one-year extension may be granted by the Doctoral School's Standing Committee, upon the submission of a reasoned application by the academic committee of the doctoral programme.

Dismissal from the doctoral programme
A doctoral candidate may be dismissed from a doctoral programme for the following reasons:

• The doctoral candidate submitting a justified application to withdraw from the programme.
• The maximum period of study and of extensions thereof ending.
• The doctoral candidate not having enrolled every academic year (unless he or she has been authorised to temporarily withdraw).
• The doctoral candidate failing two consecutive assessments.
• The doctoral candidate having disciplinary proceedings filed against him or her that rule that he or she must be dismissed from the UPC.

Dismissal from the programme implies that doctoral candidates cannot continue studying at the UPC and the closing of their academic record. This notwithstanding, they may apply to the academic committee of the programme for readmission and the committee must reevaluate them in accordance with the criteria established in the regulations.

Organization

• Jimenez Pique, Emilio

• Arencon Osuna, David
• Jimenez Pique, Emilio
• Mas Moruno, Carlos
• Santana Perez, Orlando

• Department of Materials Science and Metallurgy (PROMOTORA)

Diagonal-Besòs Campus Management and Support Unit
Building A
Av. Eduard Maristany, 16
08019 Barcelona

Tel: (+34) 934 011 792
Email: doctorat.eebe@upc.edu

Agreements with other institutions

Access profile

Given the multidisciplinary nature of the scientific field of the programme, there are a wide range of degrees that qualify applicants for admission. The applicants considered most suitable for admission to the doctoral programme in Materials Science and Engineering are bachelor’s degree holders with a scientific and technological background who have completed a master's degree in Materials Science and Advanced Materials Engineering or a related field.

In addition to having suitable academic qualifications, it is considered important that applicants have certain personal characteristics – namely, an interest in the research projects carried out within the framework of the programme; critical and analytical skills; initiative, perseverance and persistence in their academic work; the ability to work in a team; and the ability to communicate effectively in English, both orally and in writing.

The main entrance qualifications for the programme are as follows:

Bachelor’s degree in Engineering or higher engineering degree (Industrial, Materials or Chemical Engineering) or a pre-EHEA degree in Physical and/or Chemical Sciences with a master’s degree in Materials Science and Engineering (or proof of having completed 60 ECTS credits of this master’s degree), or another master’s degree with the same content, from any higher education institution in the EHEA, or a non-EHEA country if the applicant is eligible for admission to doctoral studies in that country.

Students with the following qualifications are eligible for direct admission:

Bachelor’s degree in Engineering (Industrial, Materials, Chemical or similar) or a pre-EHEA degree in Physics and/or Chemistry with a master’s degree in Materials Science and Engineering.

With bridging courses:

Holders of a bachelor’s degree in Engineering (Industrial, Materials, Chemical or similar) or a pre-EHEA degree in Physics and/or Chemistry who have completed a master's degree in a field other than Materials Science and Engineering. If admitted, these students will be required to take bridging courses carrying up to 60 ECTS credits (subjects of the master’s degree that they have not taken).

Access requirements

Applicants must hold a Spanish bachelor’s degree or equivalent and a Spanish master’s degree or equivalent, provided they have completed a minimum of 300 ECTS credits on the two degrees (Royal Decree 43/2015, of 2 February)

In addition, the following may apply:

• Holders of an official degree awarded by a university in Spain or any other country in the European Higher Education Area, pursuant to the provisions of Article 16 of Royal Decree 1393/2007, of 29 October, which establishes official university course regulations, who have completed a minimum of 300 ECTS credits on official university degrees, of which at least 60 must be at the master's degree level.
• Holders of an official Spanish bachelor’s degree comprising at least 300 credits, as provided for by EU regulations. Holder of degrees of this kind must complete bridging courses unless the curriculum of the bachelor’s degree in question included research training credits equivalent in value to those which would be earned on a master's degree.
• Holders of an official university qualification who, having passed the entrance examination for specialised medical training, have completed at least two years of a training course leading to an official degree in a health-sciences specialisation.
• Holders of a degree issued under a foreign education system. In these cases, homologation is not required, but the UPC must verify that the degree certifies a level of training equivalent to an official Spanish master's degree and qualifies the holder for admission to doctoral studies in the country where it was issued. Admission on this basis does not imply homologation of the foreign degree or its recognition for any purpose other than admission to doctoral studies.
• Holders of a Spanish doctoral qualification issued under previous university regulations.

Note 1: Doctoral studies entrance regulations for holders of an undergraduate degree awarded before the introduction of the EHEA (CG 47/02 2014)

Note 2: Governing Council Decision 64/2014, which approves the procedure and criteria for assessing the fulfilment of academic admission requirements for doctoral studies by holders of non-homologated foreign degrees (CG 25/03 2014)

Admission criteria and merits assessment

Weighting of admission criteria:

Training complements

Enrolment period for new doctoral students

The ordinary enrolment period starts in September and ends on 15 October of each academic year, though the enrolment date will depend on the admission decision.

More information at the registration section for new doctoral students

Enrolment period

The enrolment period will be from 15 September to 15 October of each academic year.

More information at the general registration section

Procedure for the preparation and defense of the research plan

Doctoral candidates must submit a research plan, which will be included in their doctoral student activity report, before the end of the first year. The plan may be improved over the course of the doctoral degree. It must be endorsed by the tutor and the supervisor, and it must include the method that is to be followed and the aims of the research.

At least one of these annual assessments will include a public presentation and defence of the research plan and work done before a committee composed of three doctoral degree holders, which will be conducted in the manner determined by each academic committee. The examination committee awards a Pass or Fail mark. A Pass mark is a prerequisite for continuing on the doctoral programme. Doctoral candidates awarded a Fail mark must submit a new research plan for assessment by the academic committee of the doctoral programme within six months.

The committee assesses the research plan every year, in addition to all of the other activities in the doctoral student activity report. Doctoral candidates who are awarded two consecutive Fail marks for the research plan will be obliged to definitely withdraw from the programme.

If they change the subject of their thesis, they must submit a new research plan.

Formation activities

Activity: Preparation and initial defence of research plan.
Hours: 4.
Type: compulsory

Activity: Programme-specific courses, seminars and workshops.
Hours: 15.
Type: compulsory

Activity: Programme-specific courses, seminars and workshops.
Hours: 40.
Type: optional

Activity: Complementary courses and seminars given by visiting professors.
Hours: 12.
Type: optional

Activity: Publications
Hours: 100.
Type: optional

Activity: Research stays.
Hours: 480.
Type: optional

Activity: Cross-disciplinary activities.
Hours: 15.
Type: compulsory

Activity: Cross-disciplinary activities.
Hours: 30.
Type: optional

Procedure for assignment of tutor and thesis director

The academic committee of the doctoral programme assigns a thesis supervisor to each doctoral candidate when they are admitted or enrol for the first time, taking account of the thesis supervision commitment referred to in the admission decision.

The thesis supervisor will ensure that training activities carried out by the doctoral candidate are coherent and suitable, and that the topic of the candidate’s doctoral thesis will have an impact and make a novel contribution to knowledge in the relevant field. The thesis supervisor will also guide the doctoral candidate in planning the thesis and, if necessary, tailoring it to any other projects or activities undertaken. The thesis supervisor will generally be a UPC professor or researcher who holds a doctoral degree and has documented research experience. This includes PhD-holding staff at associated schools (as determined by the Governing Council) and UPC-affiliated research institutes (in accordance with corresponding collaboration and affiliation agreements). When thesis supervisors are UPC staff members, they also act as the doctoral candidate’s tutor.

PhD holders who do not meet these criteria (as a result of their contractual relationship or the nature of the institution to which they are attached) must be approved by the UPC Doctoral School's Standing Committee in order to participate in a doctoral programme as researchers with documented research experience.

The academic committee of the doctoral programme may approve the appointment of a PhD-holding expert who is not a UPC staff member as a candidate’s thesis supervisor. In such cases, the prior authorisation of the UPC Doctoral School's Standing Committee is required. A UPC staff member who holds a doctoral degree and has documented research experience must also be proposed to act as a co-supervisor, or as the doctoral candidate’s tutor if one has not been assigned.

A thesis supervisor may step down from this role if there are justified reasons (recognised as valid by the committee) for doing so. If this occurs, the academic committee of the doctoral programme will assign the doctoral candidate a new thesis supervisor.

Provided there are justified reasons for doing so, and after hearing any relevant input from the doctoral candidate, the academic committee of the doctoral programme may assign a new thesis supervisor at any time during the period of doctoral study.

If there are academic reasons for doing so (an interdisciplinary topic, joint or international programmes, etc.) and the academic committee of the programme gives its approval, an additional thesis supervisor may be assigned. Supervisors and co-supervisors have the same responsibilities and academic recognition.

The maximum number of supervisors of a doctoral thesis is two: a supervisor and a co-supervisor.

For theses carried out under a cotutelle agreement or as part of an Industrial Doctorate, if necessary and if the agreement foresees it this maximum number of supervisors may not apply. This notwithstanding, the maximum number of supervisors belonging to the UPC is two.

More information at the PhD theses section

Permanence

The academic committee of the programme may authorise an extension of up to one year for full-time doctoral candidates who have not applied to deposit their thesis by the end of the three-year period of study, in the terms outlined in the Academic Regulations for Doctoral Studies of the Universitat Politècnica de Catalunya. In the case of part-time candidates, an extension of two years may be authorised. In both cases, in exceptional circumstances a further one-year extension may be granted by the Doctoral School's Standing Committee, upon the submission of a reasoned application by the academic committee of the doctoral programme.

A doctoral candidate may be dismissed from a doctoral programme for the following reasons:

• The doctoral candidate submitting a justified application to withdraw from the programme.
• The maximum period of study and of extensions thereof ending.
• The doctoral candidate not having enrolled every academic year (unless he or she has been authorised to temporarily withdraw).
• The doctoral candidate failing two consecutive assessments.
• The doctoral candidate having disciplinary proceedings filed against him or her that rule that he or she must be dismissed from the UPC.

Dismissal from the programme implies that doctoral candidates cannot continue studying at the UPC and the closing of their academic record. This notwithstanding, they may apply to the academic committee of the programme for readmission and the committee must reevaluate them in accordance with the criteria established in the regulations.

International Mention

The doctoral degree certificate may include International Doctorate mention. In this case, the doctoral candidate must meet the following requirements:

a) During the period of study leading to the award of the doctoral degree, the doctoral candidate must have spent at least three months at a respected higher education institution or research centre outside Spain to complete courses or do research work. The stays and activities carried out must be endorsed by the thesis supervisor and authorised by the academic committee of the programme. The candidate must provide a certifying document issued by the person responsible for the research group of the body or bodies where the stay or activity was completed. This information will be added to the doctoral student’s activity report.
b) Part of the thesis (at least the summary and conclusions) must be written and presented in one of the languages commonly used for science communication in the relevant field of knowledge, which must not be an official language of Spain. This rule does not apply to stays and reports in Spanish or to experts from Spanish-speaking countries.
c) At least two PhD-holding experts belonging to a higher education institution or research centre outside Spain must have issued officially certified reports on the thesis.
d) The thesis examination committee must have included at least one PhD-holding expert from a higher education or research institution outside Spain who was not responsible for the candidate’s stay abroad (point a) above).
e) The thesis defence must have taken place on UPC premises or, in the case of joint programmes, at the location specified in the collaboration agreement.

List of authorized thesis for defense

• LIANG, JING: Micromechanics of quaternary AICrSiN coatings on hard substrates
  
  Author: LIANG, JING
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Normal
  Deposit date: 20/07/2023
  Reading date: 27/10/2023
  Reading time: 12:00
  Reading place: EEBE, Sala Polivalent de l'Edifici A, planta baixa, Campus Diagonal-Besòs
  Thesis director: JIMENEZ PIQUÉ, EMILIO
  Committee:
       PRESIDENT: GARCÍA LORENTE, JOSÉ ANTONIO
       SECRETARI: FARGAS RIBAS, GEMMA
       VOCAL: GUTIÉRREZ MORA, FELIPE
  Thesis abstract: AlCrSiN quaternary coatings are extensively utilized in the tool industry due to their outstanding mechanical performance as protective coatings. These coatings are formed by introducing elements of Al and Si to enhance the mechanical properties of the CrN binary coating. Among various methods, physical vapor deposition (PVD) is widely employed in the cutting tool industry to improve the performance of hard materials. In this doctoral thesis, AlCrSiN quaternary coatings were prepared using PVD and deposited on substrates with different hardness levels.The thesis investigates the mechanical performance of AlCrSiN quaternary coatings deposited on two soft substrates after undergoing thermal treatment to simulate service conditions. The hardness and elastic modulus of the AlCrSiN coating increased when deposited on all substrates at a lower temperature of 500°C. However, these properties decreased at a higher temperature of 800°C, indicating material degradation. Compared to AlTiSiN coating, ACrSiN coating samples exhibited lower adhesion and larger spalled areas after all thermal treatments. Among the substrates, the coatings deposited on Inconel 718 demonstrated significantly better mechanical performance, particularly at high temperatures.In the second part, a comparative study of the mechanical performance was conducted on AlCrSiN quaternary coatings deposited on two hard substrates: WC-Co and cBN. The crystalline structure of the AlCrSiN coating was not influenced by the substrates in terms of intrinsic hardness and elastic modulus. AlCrSiN coating deposited on the WC- Co substrate exhibited better adhesion compared to the coating on the cBN substrate, irrespective of the load conditions. The results of the mechanical response under Hertzian loads revealed that AlCrSiN coating deposited on WC-Co substrate demonstrated superior resistance to both monotonic and cyclic loads compared to the coating on cBN substrates. The difference in the mechanical performance of the AlCrSiN coating on substrates with varying hardness depended on both the adhesion strength and the distinct mechanical performance of the substrate.The final part of the thesis focused on the effect of Zr/Ta ion implantation on the mechanical properties of AlCrSiN quaternary coatings deposited on the hard WC-Co substrate. Both Zr and Ta ion implantations led to a decrease in hardness and elastic modulus. The analysis of X-ray photoelectron spectroscopy (XPS) revealed a transformation of the metal bonding from Al-Al and Cr-Cr to Al-N and Cr-N metal nitride chemical bonding, respectively. The crystalline structure of the AlCrSiN coating remained relatively unchanged, maintaining a (Cr,Al)N solid solution, regardless of ion implantation. Additionally, a small amount of zb-AlN was detected in the case of Zr ion implantation. The adhesion strength between the coating and substrate improved after ion implantation, with Ta ion implantation exhibiting the best performance.
  

Last update: 04/10/2023 04:45:29.

List of lodged theses

• GARCÍA MASABET, VIOLETA DEL VALLE: Blends of modified PLA and Biopolyamides for additive manufacturing
  
  Author: GARCÍA MASABET, VIOLETA DEL VALLE
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Normal
  Deposit date: 29/09/2023
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: SANTANA PEREZ, ORLANDO ONOFRE | MASPOCH RULDUA, MARIA LLUÏSA
  Committee:
       PRESIDENT: SANCHEZ SOTO, MIGUEL ANGEL
       SECRETARI: XURIGUERA MARTÍN, MARÍA ELENA
       VOCAL: SAMPER MADRIGAL, MARIA DOLORES
  Thesis abstract: The main objective of this work is to counteract the limitations of polylactic acid (PLA) and propose a sustainable manufacturing approach using bioblends of a rheologically modified PLA by reactive extrusion (RExPLA) with predominantly biobased polyamides (BioPA), namely PA10.10 and PA6.10. The study was divided in three phases. The first one focuses on the preparation and characterization of bioblends prepared by internal mixer in compositions that ranged from 10% to 50% w/w of BioPA. The aim of the study was to assess the morphological, thermal, and mechanical modifications achieved by modifying the rheological behavior of the matrix. Regardless of the matrix or BioPA, when using a 30% w/w of BioPA the blend showed a ductile behavior. The use of RExPLA resulted in finer morphologies with enhanced mechanical properties. Specifically, RExPLA/PA10.10 bioblends achieved the brittle-to-ductile transition with only 10 wt% and the phase inversion was observed at a 40% w/w of BioPA. Meanwhile, in the other bioblends this situation was not observed in the composition range studied. According to the results of mechanical test, the compositions that offered better balance of performance was 20% and 30% w/w of PA10.10. In terms of thermal behavior, the use of PA6.10 seems to promote PLA crystallization.The second phase focuses on the preparation by twin-screw extrusion of the blends with the compositions previously selected (20% and 30% w/w of PA10.10) and the study of the induction of microfibrillation of the PA phase. Rheological analyses were performed on the parent polymers to assess the microfibrillation potential of PA. The effect of processing conditions, including screw rotation rate (30 and 100 rpm) and take-up rate, were evaluated to establish three draw ratios (DR) on the extruded filaments to determine the microfibrillation potential of the BioPA phase, during compounding of the blends. A preliminary evaluation shows that 20% w/w of PA could not generate a stable microfibrillated morphology; so the study focused on the composition 30% w/w.When RExPLA was used as the matrix, PA microfibrillation was achieved regardless of the applied DR, whereas for unmodified PLA bioblends a higher DR was required. Dynamic mechanical thermal analysis (DMTA) revealed that the use of RExPLA resulted in improved mechanical performance in the rubbery region due to the PA microfibrillation obtained. This microfibrillation morphology seems to improve the PLA crystallization process during the refrigeration stage.The third phase focuses the feasibility of producing in situ microfibrillated composites (MFCs) of RExPLA/PA10.10 using Fused Filament Fabrication (FFF) with pellets as feedstock. The mechanical behavior and structural integrity using Crack Tip Opening Displacement (CTOD) of the bioblends was evaluated. Morphological observations demonstrated that FFF technique enabled the fabrication of in situ MFCs with PA microfibrils of high aspect ratios. According to the mechanical characterization results, it could be concluded that in conventional manufacturing methods the use of blends PLA/PA with a sea-island morphology often results in decreased strength and stiffness compared to neat PLA. However, by tailoring the morphology of PA phase to a microfibrillar structure, the detrimental effects on mechanical properties can be mitigated. Interestingly, when employing FFF as the manufacturing process, a finer microfibrillated morphology can be achieved, while still maintaining similar strength to the matrix with high values of ductility. Even more, the toughness exhibited remarkable improvement, as evidenced by a 206% increase in CTOD values compared to the matrix. In contrast, conventional compression-molding with a sea-island morphology yielded a 44% increase in CTOD values.
  
• LOPEZ AGUILAR, JOSE FERNANDO: Escenarios hacia una economia circular de los plásticos: Caracterización del sector del envasado y evaluación de la idoneidad del reciclado Open Loop de la fracción mezclada de los residuos de envase
  
  Author: LOPEZ AGUILAR, JOSE FERNANDO
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Normal
  Deposit date: 02/10/2023
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: MASPOCH RULDUA, MARIA LLUÏSA | PEÑA ANDRES, FRANCISCO JAVIER
  Committee:
       PRESIDENT: RIERADEVALL PONS, JOAN
       SECRETARI: GONZÁLEZ COLOMINAS, MARTA
       VOCAL: MARTÍNEZ GASOL, CARLES
  Thesis abstract: This thesis aims to deepen in the understanding of the circular economy of plastics through a scientific and design approach. It has focused on packaging waste as it is the sector with the highest priority and contribution to the European legislation for the transition to a circular economy of plastics. This legislation states that at least 50% of its plastic waste must be available to be recycled by 2025. The waste production and management system was first characterized using MFA (material flow analysis) and LCA (life cycle assessment). The second part of the research is focused on understanding the mixed fraction of waste and the behaviour of the materials obtained from its open loop recycling. That was conducted characterizing the materials and their application. Using the principles of ¿cascade recovery¿, a suitability indicator has been modelled, useful for design decisions and the definition of circularity policies.The main results indicate that the effective recycling rate in Spain for 2017 (the last year for which figures are available) is 11%, far below the 50% required by European regulations and even further away from the 70% declared by the official organism in charge of its management and monitoring. The figures are also difficult to improve, even if selective collection were to increase, due to the high presence of around 50% of film plastics, with very low recyclability. In order to achieve the EU¿s objectives, an alternative solution based on technically and economically viable solutions has been proposed. Even though it would greatly improve the circularity of the system, it would also lead to an increase in GHG emissions and a pressure on forest resources that is not sutainable.The second part of the thesis focused on the characterisation of the mixed fraction of plastics, as it is the material stream that will play the most important role in a scenario of massive selective collection. It is also the least known fraction. The recycled materials obtained have been characterised in terms of composition, shaping processes, mechanical properties, environmental impact and aesthetic features. On this basis, an investigation has been conducted into the range of applications that have been manufactured using that material over the last 20 years. An environmental modelling of open loop recycling has been developed by evaluating the substitution of different types of materials and comparing it to a hypothetical close loop recycling of plastics. According to the results, the environmental performance of open loop recycling is superior to that of close loop recycling in almost all scenarios and is therefore a preferable alternative in terms of CO2 emissions.In the third block of the investigation, the potential for implementation in the mixed plastic market is defined. The suitability of the different applications taking into account both the ecological credentials, as well as the aesthetics and the industrial operation has been determined. The results indicate that applications such as road markings and reusable industrial packaging are highly suitable applications for mixed recycled plastics with a large potential market. However, an important problem has been detected in terms of aesthetics and smell for use in domestic products. Once the most suitable applications and their respective market shares have been determined, the consequences at a national scale of the massive introduction of a new flow of materials such as mixed recycled plastic has been evaluated. The results obtained indicate that open loop recycled plastic has a greater potential for improving the circularity of plastics than close loop recycled plastic, with a greater potential for reducing CO2 emissions and with a greater potential market.
  
• PARAREDA ORIOL, SERGI: A damage-based fatigue life prediction method for metallic alloys and composites
  
  Author: PARAREDA ORIOL, SERGI
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Article-based thesis
  Deposit date: 02/10/2023
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: MATEO GARCIA, ANTONIO MANUEL | CASELLAS PADRO, DANIEL
  Committee:
       PRESIDENT: BUSQUETS MATAIX, DAVID JERONIMO
       SECRETARI: LLANES PITARCH, LUIS MIGUEL
       VOCAL: CARRERAS BLASCO, LAURA
  Thesis abstract: Fatigue failures in materials have been studied for centuries, with early pioneers like August Wöhler noting that repeated loading, even below the static strength of the material, could lead to structural deterioration. Despite decades of research by notable authors, fatigue remains a complex and challenging issue, accounting for most service failures in metallic and composite structures. Therefore, designing structures to withstand cyclic loads without compromising integrity is crucial. But this process requires conducting numerous fatigue tests to define the appropriate design stress levels for each material and condition.However, determining the fatigue behaviour of metallic alloys and composites through standardised testing methods is often costly and time-consuming. While various techniques have been proposed to expedite testing and enhance the optimisation of materials and components for fatigue resistance, they have not gained wide industry adoption due to limitations in equipment or complex data treatment. Thus, there is an industry need for a testing method that rapidly determines material fatigue resistance, especially in the automotive sector where new designs and developments require results in a short time.To address this challenge, the development of a new testing method for characterising the fatigue resistance of metallic alloys and composites has become essential, as current solutions like ultra-high frequency testing machines or the rapid testing methods using temperature variations are not universal solutions for all these materials. In this thesis, a novel fatigue testing method, named the stiffness method, is introduced to rapidly assess the fatigue resistance of both metallic and composite materials with minimal specimens and in a short timeframe. This approach involves monitoring fatigue damage using different variables, such as inelastic strain in metallic alloys and compliance in composites. These measurements overcome the limitations of other methods by using common extensometers like digital image correlation techniques and contact extensometers.The results obtained through the stiffness method are not only convincing but also more accessible for interpretation and discussion compared to other monitoring techniques, such as temperature dissipation. The effectiveness of this approach has been validated across nineteen metallic materials, including titanium and aluminium alloys, carbon steels, stainless steels, and one carbon-fibre composite. The estimated fatigue limit and high cycle fatigue curve (S-N curve) obtained through the stiffness method align excellently with values derived from standardised tests. This underscores the method as a powerful and efficient tool for swiftly assessing the fatigue behaviour of both metallic alloys and composite materials.Furthermore, this research investigates the fatigue reduction observed in high-strength steels when surface defects are introduced during manufacturing processes such as shearing. This reduction in fatigue resistance is explained by the fatigue notch sensitivity of the material. The results establish a robust correlation between fracture toughness, assessed within the framework of fracture mechanics, and fatigue notch sensitivity in high-strength steels. As a result, fracture toughness coupled with the stiffness method can be a valuable toolkit for selecting materials with superior fatigue resistance.In summary, this work presents an innovative and efficient approach to evaluate the fatigue behaviour of metallic alloys and composite materials, offering significant advantages in terms of time and resource savings. Additionally, it introduces fracture toughness as a valuable indicator for material selection in high-strength steel applications, ultimately contributing to improved fatigue performance.
  

Last update: 04/10/2023 04:30:30.

List of defended theses by year

• CARPIO GARZA, MARCEL FRANCISCO: Development of quenching and partitioning steels (Q&P)
  
  Author: CARPIO GARZA, MARCEL FRANCISCO
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Normal
  Reading date: 07/06/2023
  Thesis director: CABRERA MARRERO, JOSE MARIA | CALVO MUÑOZ, JESICA
  

  Committee:
       PRESIDENT: LLORCA ISERN, NURIA
       SECRETARI: BARRIOBERO VILA, PERE
       VOCAL NO PRESENCIAL: MEJÍA GRANADOS, IGNACIO
  Thesis abstract: The automotive industry is constantly seeking to improve the performance of the car and at the same time reduce CO2 emissions into the environment, which can be achieved among other solutions through the use of advanced high-strength steels (AHSS) that help reduce the weight of the car and keep the safety of the passengers.The search for new steels with better mechanical properties has led researchers to design new alloys with different microstructures. The focus of new research is focused on the development of the 3rd generation of AHSS, which present a good relationship between resistance with a considerable increase in ductility compared to previous generations. It has been seen that this generation of new steels must present a microstructure partially formed by austenite which presents the TRIP effect or transformation induced plasticity. Said microstructure, when submitted to a deformation, transforms into martensite, improving its resistance, while at the same time providing toughness and/or formability to the steel.One of these steels is called quenching and partitioning (Q&P) steel, which have a good relationship between strength and ductility due to their microstructure made up of retained austenite, fresh martensite, and tempered martensite. The production process of these steels is divided in two steps: the first step consists of an intercritical or complete austenitizing treatment, followed by an interrupted quench between the Ms and Mf temperatures to ensure a fraction of austenite, martensite and/or ferrite as required. The second step consists of a partitioning treatment in which a reheat is applied to a particular temperature for a given residence time. During this step, the carbon contained in the supersaturated martensite diffuses into the remaining austenite, stabilizing it at room temperature, followed by a quenching treatment to finish the process.In this thesis, three steels with different amounts of manganese by weight (1.5Mn, 3.5Mn and 5.5Mn) in their chemical composition are designed together with 0.2C% and 1.5Si% (%weight) and are subjected to a industrial Q&P process with parameters designated by the company TERNIUM México. After the heat treatments, the steels were analyzed by means of different characterization techniques for their evaluation.The objectives of this work were to find the best heat treatment route and its implementation at an industrial level, to determine the effect of the manganese concentration in the steel, in terms of the QP treatment, and to obtain a microstructure with the highest possible toughness, maximizing the fraction of retained austenite.From the results obtained it can be determined that: theoretical models do not accurately predict the amount of retained austenite, especially due to Mn segregation problems. On the other hand, although increasing the Mn content tends to increase the retained austenite content, it also increases the risk of generating a lot of fresh martensite in the last step of the QP treatment, which is detrimental for the final mechanical properties. For the 1.5Mn steel, good mechanical properties were obtained due to the microstructure achieved during the Q&P process, which presented a mixture of retained austenite, fresh martensite, tempered martensite, and bainite. On the other hand, the 3.5Mn steel presented the highest fraction of retained austenite with good mechanical properties compared to the other steels. Similarly, the 5.5Mn steel showed an increase in segregation and therefore high manganese zones, in which they tend to present a higher fraction of fresh martensite, reducing the carbon available to stabilize the retained austenite by reducing its final fraction. From the results of the mechanical tests it can be determined that a high fraction of retained austenite does not always ensure good ductility because it also increases the risk of generating a significant amount of fresh martensite.
  

• CHAUSSE CALBET, VICTOR: 3D-printed Polymeric Bioresorbable Stents for Cardiovascular Applications
  
  Author: CHAUSSE CALBET, VICTOR
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Normal
  Reading date: 26/05/2023
  Thesis director: PEGUEROLES NEYRA, MARTA
  

  Committee:
       PRESIDENT: CIURANA GAY, JOAQUIM
       SECRETARI: GODOY GALLARDO, MARIA
       VOCAL: MARTORELL LOPEZ, JORDI
  Thesis abstract: Bioresorbable stents (BRS) have been envisioned as a revolution in the treatment of coronary heart disease. Ideally, stents would initially retain sufficient radial strength after implantation to prevent vessel recoil while degrading and ultimately being resorbed, thus leaving the vessel with a healthy endothelium. Still, the main challenge of BRS lies in simultaneously providing enough mechanical support to prevent recoil in the first months while controlling the degradation rate, minimizing strut thickness and improving BRS hemocompatibility and tissue integration.The main aim of the present PhD Thesis is the design and development of tunable novel polymeric bioresorbable stents manufactured by means of solvent-cast direct-writing (SC-DW) with reinforced mechanical properties, suitable degradation timeframe, drug release capability and enhanced biointegration.First, a novel versatile additive manufacturing fabrication strategy for BRS production by using polymeric inks and SC-DW onto a rotating cylinder is presented. Initially, poly-L-lactic acid (PLLA) was used to manufacture and characterize a variety of designs with different mesh patterns. In a second step, poly(L-lactic-co-caprolactone) (PLCL) was introduced, and inks were further modified with the addition of iodine, triiodobenzoic acid (TIBA) and barium sulfate (BaSO4) in order to produce radiopaque BRS. Microcomputed tomography was used to assess stents' radiopacity, showing that TIBA and BaSO4-containing stents presented high X-Ray attenuation values, maintained over 3 months incubation time.With the aim to gain further insight into PLLA and PLCL stents degradation, a complete study was performed by comparing chemical vs thermal accelerated degradation assays. The results showed that under alkaline conditions, stents underwent surface erosion, whereas stents immersed at 50 ºC experienced bulk degradation. Molecular weight decrease was accurately described by the autocatalyzed kinetic model, with PLCL showing a degradation rate 1.5 times higher than PLLA. Regarding sterilization, whereas EtO-sterilized stents remained structurally unaltered, ¿-irradiated stents presented severe deterioration as a result of extensive chain scission.In the following, a combination of SC-DW and electrospinning (ES) was proposed as a new approach to generate everolimus-eluting BRS for cardiovascular applications. A Design of Experiment was conducted to determine the parametersnecessary for optimal homogeneous coating with high specific surface. Drug loading was achieved either encapsulated in the struts of the stent or in an electrospun PLCL membrane covering the stent. When encapsulated, everolimus release was found to be insufficient, whereas release from PLCL-coated 3D-printed stents would match the dose and timeframe required for in vivo applications.Finally, functionalization of 3D-printed PLLA and PLCL BRS with endothelial cell (EC) adhesive peptides was explored. Solid phase peptide synthesis was used to synthesize linear RGDS and YIGSR sequences, as well as a dual peptidic platform (PF) containing both motifs in a single biomolecule. Endothelial cell adhesion assays evidenced significantly increased cell number and spreading onto functionalized films with respect to control samples. Stents' hemocompatibility was evaluated upon a blood perfusion assay, with PLCL showing pronouncedly diminished platelet adhesion with reference to PLLA. In addition, functionalization with RGDS, YIGSR and the PF rendered BRS stents displaying even further reduced platelet adhesion.
  

• DA SILVA LIMA, MARCOS NATAN: Effect of deformation on the mechanical behavior of an advanced steel of high resistance with high manganese content
  
  Author: DA SILVA LIMA, MARCOS NATAN
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Change of supervisor
  Reading date: 30/06/2023
  Thesis director: CABRERA MARRERO, JOSE MARIA | CALVO MUÑOZ, JESICA | FERREIRA GOMES DE ABREU, HAMILTON
  

  Committee:
       PRESIDENT: PARDAL, JUAN MANUEL
       SECRETARI: MUÑOZ BOLAÑOS, JAIRO ALBERTO
       VOCAL: SOUTO MAIOR TAVARES, SERGIO
  Thesis abstract: Pre-salt oil exploration means a new development path for Brazil. This activity stimulates investments from national and foreign companies, boosts the production of technology, promotes greater professional qualification and generates employment and income. The flexible pipelines (risers) used in the extraction of gas and oil from the seabed have a traction reinforcement made of steel that must withstand various efforts such as axial traction, fatigue, high pressure, torsion and corrosion when in service. The present research carried out a study of the mechanical behavior of a special steel with high manganese and medium chromium. Ordinary and severe (Severe Plastic Deformation-SPD) plastic deformations were applied to high manganese steel to establish a comparative degree of mechanical strength, tenacity, and corrosion of this steel with pearlitic steels currently used in flexible ducts. The steel used in this work has a TWIP (Twinning Induced Plasticity) effect, which caused the appearance of mechanical twins after plastic deformation.The correlation between microstructure, crystallographic orientation, and grain boundary characteristics of austenitic high manganese steel was systematically investigated. In the first stage, cold rolling was performed. The as-received and cold-rolled specimens with 50% and 70% reduction were analyzed using Scanning Electron Microscopy (SEM), Electron Back-Scattered Diffraction (EBSD), and X-ray diffraction techniques. A significant increase in the fraction oflow-energy S3 twin boundaries, from 16.21% to 24.41%, was found in the 70% deformed sample. This was coupled with the formation of {011} austenitic structure and the occurrence of twinning-induced plasticity. The ductile-brittle fracture mode observed in the 70% cold rolled sample, which can be attributed to the formation of the high fraction of low-energy S3 twin boundaries, minimized both the localized stored strain energy and lattice misfit, and promoted dislocation glide. In order to improve material properties, severe plastic deformation processes such as ECAP (Equal Channel Angular Pressing) have been used. Thus, in the second stage, a steel with ultrafine grain size was obtained after severe plastic deformation by ECAP at two processing temperatures (350 ¿C and 250 ¿C), using a die with an internal angle ¿=120°, and an angle of ¿=30° that defines the external arc of curvature where the two channels intersect. The material was processed following the (Bc) route for different numbers of passes (1, 2, 4 and 8 passes). Microstructural characterization was performed using technologies such as SEM, EBSD and X-ray diffraction. The textures obtained after each pass show predominant orientation with continuous distributions along the fiber orientation with pure shear. Mechanical characterization by hardness and uniaxial tensile testing was carried out. According to these mechanical tests, the resistance of the material increases with deformation until it reaches an increase of ~2 times in relation to the received material.In the third stage, the steel underwent a hot torsion test. Steel samples with high manganese content were subjected to continuous isothermal torsion tests. Two strain routes were performed, ¿ = 2.5 (route A) and ¿ = 3.0 (route B), was used with a strain rate of 0.05 s-1 at a temperature of 900°C. The results showed a competition between dynamic hardening and softening mechanisms (i.e. recovery and recrystallization). This observation is also a consequence of the stacking fault energy (SFE) variation and the twinning-induced plasticity effect (TWIP) with the applied strain.
  

• GARCIA MINTEGUI, CLAUDIA: Bioresorbable Zn-based alloys for biomedical applications
  
  Author: GARCIA MINTEGUI, CLAUDIA
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Normal
  Reading date: 26/01/2023
  Thesis director: PEGUEROLES NEYRA, MARTA | CORTINA PALLAS, JOSE LUIS
  

  Committee:
       PRESIDENT: FERNÁNDEZ GONZÁLEZ, JAVIER
       SECRETARI: CALERO MARTINEZ, JOSÉ ANTONIO
       VOCAL: BULUTSUZ, ASLI GÜNAY
  Thesis abstract: Biodegradable metals emerged as promising materials for bioresorbable devices avoiding the potential side effects of permanent implants. Among them, zinc (Zn) arose dueto its suitable degradation rate for biomedical application, but it needs to be alloyed for mechanical reinforcement via sol id precipitation hardening. However, the secondary phases lead to galvanic corrosion and poor biocompatibility. So far, the compromise among mechanical strength, corrosion rate, and biological response of Zn alloys remains unknown.This PhD Thesis aims to gain an increased understanding of Zn-based alloys for biomedical applications, establishing correlations between Zn matrix and secondary phases and controlling corrosion behaviour and in vitro biological response. Chapter I characterized Zn-xMg (x = 0.5, 1 wt. %) and Zn-xCu (x = 3, 5 wt.%) alloys for bioresorbable cardiovascular stents. Tensilé tests confirmed that alloying with Mg or Cu significantly increased the yield strength (YS), ultimate tensile strength (UTS), and elongation at fracture. Nanoindentation tests confirmed mechanical reinforcement dueto the precipitation of Zn+Mg2Zn11 and E-CuZn5 phases for Zn-Mg and Zn-Cu, respectively. Degradation tests in Hanks' solution indicated the formation of galvanic pairs between secondary phases and Zn matrix. Zn-Cu alloys presented antibacterial activity against S. aureus and P. aeruginosa, but cytotoxicityto endothelial cells (ECs). AII the alloys reported poor biocompatibility, attributed to local ions release into solution and degrading surfaces. Among all the samples, Zn-Mg alloys presented the best compromise among mechanical, corrosion, and biological properties.Chapter II characterized Zn-xAg (x= 2, 4 wt. %) alloys for bioresorbable ureteral stents. Tensile tests evidenced themechanical reinforcement of Zn-Ag alloys compared with pure Zn, where the higher AgZn3 volume fraction of Zn-4Ag led to reduced UTS and YS than Zn-2Ag alloy. 1\11oreover, the galvanic couple between AgZn3 and Zn of Zn-4Ag alloy resulted in severe localizad corrosion, where bacteria could infiltrate the corrosion pits hampering the antibacterial effect. In summary, Zn-2Ag presented a better degradation performance and optimal antibacterial effect.Chapter III proposed a dual-action coating for Zn-0.5Mg and Zn-2Ag alloys to control corrosion and enhance endothelialisation in cardiovascular stents. First, a pol}Caprolactone (PCL) coatir.ig was implemented on the alloys bycold plasma polymerization of E-caprolactone and PCL spin-coating. Secondly, the PCL-coated alloys were functionalized with RGD (Arg-Gly-Asp), REDV (Arg-Glu-Asp-Val), and RGD-REDV peptides synthesized via solid solution and covalently immobilized via EDC/NHS chemistry. A homogeneous PCL coating of 800 nm with good adhesion strength provided adequate corros ion resistance to both alloys. ECs successfullyadhered to the functionalized surfaces, where the RGD­ REDVplatform presented a significant increase in cell number, deinonstrating the synergistic effect of RGD and REDV peptides.Chapter IV proposed equal channel angular pressing (ECAP) (two C}Cles, route Be; R.T.) to homogenise Zn-2.Ag corrosion. Ultrafine-grained structure and randomlydistributed textura was obtained after ECAP, with no evident AgZn3 breaking or distribution. Nanoindentation mapping indicated mechanical isotropy, and corrosion studies suggested more uniform degradation after ECAP. 1\11oreover, the exceptional antibacterial activity against S. aureus was attributed to the reduction of corrosion pits and distribution of Ag through the matrix. Overall, the ECAP process acted as a potential technique for homogenising the mechanical and corrosion properties of Zn-Ag alloys with excellent antibacterial properties. In summary, PhD Thesis provided relevant clues into the proper Zn·based formulation and coating and deformation strategies to overcome the instrinsic galvanic corrosion of Zn alloys for different biomedical application
  

• LOAEZA BECERRIL, ALFONSO DAVID: Polymer blends based on postconsumer waste of opaque poly(ethylene terephthalate) and polypropylene
  
  Author: LOAEZA BECERRIL, ALFONSO DAVID
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Normal
  Reading date: 19/07/2023
  Thesis director: MASPOCH RULDUA, MARIA LLUÏSA | SANTANA PEREZ, ORLANDO ONOFRE
  

  Committee:
       PRESIDENT: FERNÁNDEZ RENNA, ANA INÉS
       SECRETARI: SANCHEZ SOTO, MIGUEL ANGEL
       VOCAL: DE LA FLOR LÓPEZ, SILVIA
  Thesis abstract: In recent years, new white and opaque PET bottles (PET-O) have appeared and are used for packaging dairy products. These bottles contain titanium dioxide (TiO2) particles to prevent deterioration of the packaged product caused by UV radiation and to minimise oxygen permeation into the interior. At the end of their useful life, during the selective collection and subsequent treatment in sorting plants before being sent to PET recycling plants, they are randomly mixed with transparent PET packaging waste (PET-T). Taking into account that one of the main applications of recycled PET-T (rPET-T) is the manufacture of synthetic fibres for the textile industry, the presence of recycled PET-O (rPET-O), and therefore TiO2, in rPET-T streams causes processability problems during filament production, impeding the spinning process. As recyclers are not adequately prepared to separate PET-O from PET-T, the mixing of both PETs leads to an increase in the reject rate of the input material at the recycling plants. Taking into account the previous question, this doctoral thesis focuses on finding an outlet for the PET waste mixture, referred to as rPET-O in this thesis, in applications that are not limited to the manufacture of textile fibres. In order to provide a balanced output and enhance the rPET-O value, has been proposed to be used as a minority phase in a polyolefin matrix to act as a reinforcing element. To this end, the microfibrillation capability of rPET-O has been explored to generate in-situ microfibrillated composites using two different manufacturing processes: sheet extrusion and fused deposition modelling (3D printing). Thus, in this thesis, recycled polypropylene (rPP) has been selected as a matrix, since it is an easily accessible raw material due to its high recycling rate. Both materials (rPP and rPET-O) were supplied by a recycling company and come from post-consumer waste, which is an added challenge to the study of this thesis. The rPP, sourced from the automotive industry, was supplied in pellet form. Differential scanning calorimetry tests showed that this material contained polyethylene (PE) in low proportions, a characteristic of the PP type used in this sector. The rPET-O, on the other hand, was supplied in flake form, and for its subsequent manipulation, these flakes were transformed into pellets by means of an extrusion process that in this thesis will be called homogenisation. From these materials, rPP/rPET-O blends were prepared with rPET-O amounts of 10, 20 and 30% by weight. An additional amount of TiO2 was added to the 80/20 blend to simulate a higher PET-O waste stream than the previous blends, the resulting blend will be referred to in this thesis as 80/20/5.After morphological analysis by scanning electron microscopy, it was observed that the 70/30 and 80/20/5 blends showed the ability to form microfibrillar structures of the second phase after processing by both sheet extrusion (0.6 mm nominal thickness) and 3D printing. Tensile tests determined that the Young's modulus of the blends containing microfibrillated rPET-O is higher, not only than that of rPP, but also than that of the other blends by up to 30%. In addition, fracture mechanics tests showed that the resistance to the initiation of slow crack propagation is more than twice as high in mixtures with microfibrillated structures compared to the rest of the blends. These findings confirmed the possibility of producing in-situ microfibrillar composites using post-consumer recycled materials from a real recycling process, obtaining 100% recycled composites with improved properties compared to the starting components
  

• LORENTE SOTERAS, ITZEL: Desarrollo de sistemas de dispersión coloidal y granulación de partículas metálicas finas
  
  Author: LORENTE SOTERAS, ITZEL
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Normal
  Reading date: 14/09/2023
  Thesis director: LLANES PITARCH, LUIS MIGUEL | CALERO MARTINEZ, JOSÉ ANTONIO | SALAN BALLESTEROS, MARIA NURIA
  

  Committee:
       PRESIDENT: AMIGÓ BORRÁS, VICENTE
       SECRETARI: MATEO GARCIA, ANTONIO MANUEL
       VOCAL: FERRARI FERNÁNDEZ, BEGOÑA
  Thesis abstract: One of the main goals of the powder metallurgical (PM) industry has been to develop powders that have favourable handling, geometrical and optimal metallurgical properties. Currently, there are two main methods of producing iron and steel powders, which account for more than 90% world production. However, sorne of these powders have physlcochemical and mechanical properties that generate complications for the press and sinter process. For example, steels with high chromium content (above 18% wt.) have a high modulus of elasticity and hardness, which makes difflcult the pressing process and, consequently, the consistency of the green compact. Powders with fine particle size ( < 20µm) can hinder the pressing process, as they migrate lnto the small gap between punch and die. They also have higher interna! energy and tend to agglomerate.To achieve the processing of this type of metal powders, this research focuses on the development of an alternative route in the production of powders for the PM industry. Accordingly, this work has a two-fold objective: to study the colloidal processing route of metals and the drying of the suspensions via spray drying, a technology that allows obtaining powders with a granular morphology. It should be noted that the agglomeration of the fine particles into granules not only improves green strength, but also allows the transformation of fine powder into a larger and quasi-spherical powder with good flowability. This improves the filling and rearrangement of particles within the compaction matrix. In addition, the granules are made of small particles with a high specific surface area. So that they manifest greater dlffusivity of atoms during the sintering process and allow a higher denslty to be achieved than would be the case with non-granulated particles of the same size, always under the same slntering conditions.After the suspensions were obtained, they were ali spray dried. Numerous tests were carried out and two different drylng heads were used, one centrifuga! and one lance-shaped. Moreover, different temperatures and drying pressures were evaluated to optimize the performance of the process. Several granulated powders were obtained, so that their metallurglcal, geometrical, and mechanical properties could be evaluated to select the composition with the best reproduclbility.The next step in this work was to study the behaviour of the developed powder In the PM field. For this reason, the best pressing conditions were determined. Then, different times and temperatures were studied for the debinding. Afterwards, the sintering process was carried out. It is important to emphasize that the achieved results, under the same pressing and sintering conditions, indicated that the obtained properties were better than those produced with the commercial granulated powder.Finally, the research focused on giving applicabllity to the granulated powder developed in this work, which was the fabrlcation of high-density interconnects by press and sinter technology to be used in Solid Oxide Fuel Cell (SOFC).
  

• MONTERDE GASCÓN, MARIA CARMEN: Nuevos interconectores pulvimetalúrgicos para sistemas de óxido sólido de alta temperatura: desarrollo, optimización y prototipado
  
  Author: MONTERDE GASCÓN, MARIA CARMEN
  Thesis link: http://hdl.handle.net/10803/688015
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Normal
  Reading date: 27/02/2023
  Thesis director: JIMENEZ PIQUÉ, EMILIO | CALERO MARTINEZ, JOSÉ ANTONIO | TORRELL FARO, MARC
  

  Committee:
       PRESIDENT: GARCÍA CANO, IRENE
       SECRETARI: MORALES COMAS, MIGUEL
       VOCAL: ETXEBERRIA URANGA, JON JOSEBA
  Thesis abstract: The transition towards to low carbon energy generation is promoting the installation of renewable energy sources, their successful deployment requires efficient energy storage systems in order to meet demand. Hydrogen generation has emerged as a good alternative for energy storage. High-temperature solid oxide electrolyze (SOEC) systems are the most efficient systems for generating hydrogen from electrolysis of water. These SOEC systems exhibit 80% energy conversion rates in the operating temperature range of 700 - 900ºC.The manufacturing techniques of the components is one of the main drawbacks of SOEC systems, and both performance and durability are under investigation in order to increase their lifetime and market penetration in competition with other electrolysis technologies with lower efficiencies.Metal interconnects are a vital part of high-temperature solid oxide systems as they electrically connect the cells and distribute the flow of gases that feed the final stack. The commercialization of these systems can be boosted by improving the lifetime and lowering the cost of these systems, which is partly driven by the high cost of the interconnect. Research is currently being carried out on ferritic stainless steel (FSS) interconnects, which are cheaper than ceramic materials, but shaw degradation problems at the high working temperatures of 750-800 ºC. Corrosion phenomena and chromium evaporation negatively affect system performance dueto increased electrlcal resistance and oxygen electrode polsoning has been shown to be effective In mitigation. The effectiveness in mitlgating these effects has been preven by the application of chromium barrier coatings such as MnCo2O4. This thesis deals with the design, developrnent, manufacture and optirnizatlon of a flat coated FSS metal lnterconnect manufactured by conventional powder metallurgy. The functionality in a single repeat unit has been validated in a high temperature electrolyze apparatus designed and built also within this study. This thesis can be divided into three blocks: i)design and fabrication by conventional powder metallurgy of a functional FSS interconnector, ii) study of various application techniques of the MnCo2O4 barrier coating such as roll coating, an additive manufacturing technique such as ink jet printing on demand (DOD) and electrophore!lc deposition (EPD), iii) design, construction and validation of a first high temperature electrolyze at national level built and validated with a commercial stack and which has been working directly connected to an industrial station such as the Riu Sec in Spain and iiii) validation of the interconnect and barrier !ayer efficiency with a commercia/ ce// in SOEC mode in tlle e/ectro/yzer for 750h at BOO"C and in SOFC mode after 150h in an /REC measurement station.In summary, this thesis deals with the design, development, manufacture and optimization of a flat coated FSS metal interconnect manufactured by conventional powder metallurgy. The functionality in a single repeat unit has been validated in a high temperature electrolyze apparatus designed and built also within this study. The results obtained show a functional interconnect in high temperature solid oxide systems in both SOFC and SOEC rnodes fabricated by conventional powder metallurgy.The results obtained show a functional interconnect in high temperature solid oxide systems in both SOFC and SOEC modes fabricated by conventional powder metallurgy.Finally, this thesis details a journey through the different maturity levels of high temperature solid oxide technology particularly in SOEC mode. The study has started ata TRL 3 proof of concept of high temperature solid oxide technology and has reached TRL 7 where a high temperature electrolyzer apparatus has been fabricated, validated and connected toan industrial installation, and a flat coated FSS metal interconnector validated on electrolyzer equipment designed and built in this study.
  

• SOLÉ MARTÍ, XAVIER: Effects of cold atmospheric plasmas on biomaterials: hydrogels and composites with calcium phosphates
  
  Author: SOLÉ MARTÍ, XAVIER
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Article-based thesis
  Reading date: 13/07/2023
  Thesis director: CANAL BARNILS, CRISTINA | GINEBRA MOLINS, MARIA PAU
  

  Committee:
       PRESIDENT: CVELBAR, URO¿
       SECRETARI: GARCÍA TORRES, JOSÉ MANUEL
       VOCAL: VÉLEZ VILLA, ROBERTO
  Thesis abstract: This PhD thesis is framed in the European Research Council starting grant project "Atmospheric Pressure plasma meets biomaterials far bone Cancer HEaling (APACHE)". The APACHE project is focused on the design of novel therapies far bone cancer by combining plasma technology with biomaterials.Cold atmospheric plasma (CAP) is an ionized gas that contains a mixture of ions, electrons, ultraviolet radiation, radicals and exited molecules that in presence of air and water, leads to an environment rich in reactive oxygen and nitrogen species (RONS). These CAP-generated RONS can be transferred to liquids by diffusion or through secondary reactions, generating a plasma-treated liquid (PTL). Research in this field suggests that CAP-generated RONS can be used to target malignant tumors, inducing apoptosis to cancer cells, without damaging healthy cells or tissues. In his context, PTLs can be injected near the tumor ar intratumorally, thereby allowing the treatment of tumors located in internal! organs that are not accessible far direct CAP treatment.Many studies have already reported promising anticancer effects of PTL in vitro and in mice models in vivo, However, the injection of a liquid to the tumor site might result in fast diffusion throughout the whole body due to body fluids, thus reducing the efficiency and efficacy of PTL. Besides, multiple PTL injections are needed to induce biological effects in vivo. In the present thesis, new strategies with plasma-treated hydrogels (PTH) are under investigation, with the aim of designing new and efficient vehicles that allow a localized release of RONS directly to the tumor site.To that aim, Chapter 1 of this PhD thesis offers a general perspective on the state of the art regarding the use of PTL treatments in vivo far anticancer purposes. The different conditions for PTL generation, tumor formation and dosage regimen among the different. studies are reviewed and discussed. In Chapter 2, an osteomimetic scaffold is synthesized in order to develop a 3D model of human osteosarcoma. This tumor tissue construct is subsequently used for the evaluation of PTL treatments in a 3D environment. To progress towards more advanced vehicles of RONS, Chapter 3 develops a methylcellulose hydrogel as a thermosensitive agent for local RONS delivery. Besides the quantification of RONS generated in the methylcellulose solution, a comprehensive physic-chemical characterization of its polymeric structure is performed before and after CAP treatment to evaluate any potential modifications due to CAP. Finally, Chapter 4 explores the in vivo osteogenic capacity of a composite material based on a plasma-treated hydrogel made of alginate and gelatin combined with a calcium phosphate ceramic, focusing on cancer cell selectivity and safety performance of such combination.In summary, the results of this PhD thesis showed that both type and amount of RONS responsible for the cytotoxic effects of PTL and PTH can be tailored by modifying the parameters of the experimental setup. In that line, we showed that CAP treatment of some biopolymeric solutions (here methylcellulose, gelatin and alginate) led to higher RONS concentrations compared to their respective solvents. Also, the PTH studied allowed a local treatment, with a slightly slower release of RONS compared to PTL. Composite materials combining PTH with osteogenic materials like calcium phosphates may have promising applications as adjuvant therapies after bone cancer resection.
  

• XIMENES CARBALLO, CELIA: Bioactive ion-releasing platforms for regenerative medicine applications
  
  Author: XIMENES CARBALLO, CELIA
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Normal
  Reading date: 07/07/2023
  Thesis director: ENGEL LOPEZ, ELISABET | CASTAÑO LINARES, OSCAR | PEREZ AMODIO, SOLEDAD GRACIELA
  

  Committee:
       PRESIDENT: ALEMAN LLANSO, CARLOS ENRIQUE
       SECRETARI: CAMALHAO LOPES DE OLIVEIRA, HUGO FERNANDO
       VOCAL: SEMINO MARGRETT, CARLOS EDUARDO
  Thesis abstract: One of the most exploited tissue-engineering-based strategies nowadays is to use scaffolds that allow local stimulation of the targeted tissues, increasing therapy effectiveness while reducing toxicity. Therefore, scaffolds mus! be designed to mimic and stimulate the natural processes that occur in tissues to allow in situ regeneration. For that purpose, researchers often rely on the use of bioactive molecules, or even cells, to stimulate and trigger the regenerative pathways. Although the use of molecules or cells may be efficient, there is a concern regarding their safety, as well as their costs, and scalability.Macro and microminerals are essential components of human tissues. Most of them, such as calcium and zinc, act as secondary messengers, enabling tissue functionality. Specifically, calcium and zinc modulate the wound healing process through ECM deposition, cell proliferation, and chemotaxis. Calcium and phosphate also affect bone signaling through remodeling and mineralization. On !he other hand, calcium has been reported to enhance angiogenesis, which is highly needed to favor regeneration and tissue integration.Therefore, sorne researchers have used these ions to develop strategies for tissue engineering. Several ion-loaded hydrogels, metal particles, or metal-organic frameworks had been widely used for treating skin and bone conditions. However, !hose materials may have limited application owing to their fas! release. Bioglasses had also been widely used in biomedical applications, especially bone-healing applications. However, their processability and tuneability may be limited, hampering their suitability for specific applications.In this thesis, we explored the fabrication of different ion-releasing platforms for wound and bone healing applications. First, we explored the incorporation of ions in polymeric platforms. Although ions could be entrapped within the polymeric particles, the release was fas!, which did not fil our objectives.Then, we explored the fabrication of a dual-ion releasing system based on calcium and zinc for soft tissue engineering. This system avoided using phosphates, which may induce tissue calcifications in the long term, as well as borates and silicates, which metabolism may be unknown. We obtained a wide range of particles, fully characterized.lnterestingly, these particles showed increased cell chemotaxis, collagen deposition, increased VEGF production, and modulated differentiation as well as wound contraction when tested in vitro using primary human dermal cells.Then, a brief study of particle incorporation into chitosan-collagen-based 3D-printed hydrogels was performed to fabricate functional platforms for the local release of ions in chronic wounds. Our results showed that chitosan concentrations needed for proper printability were toxic for dermal cells, hampering their application. Hence, further refinement of the strategies used to fabricate the 3D hydrogels need refinement.Finally, calcium-phosphate-based particles were incorporated into polylactic acid solutions to produce 3D-printed scaffolds for bone-healing applications. The incorporation of the particles enhanced the angiogenic properties of our scaffolds. In vitro, scaffolds promoted VEGF release by hMSCs. In vivo, they allowed blood vessel infiltration and maturation, enhancing the scaffold-tissue integration.In conclusion, this thesis has contributed to developing new materials that can successfully be employed as cost-effective alternatives for wound and bone healing in situ advanced therapies where bioactive ions are the main actors in the healing process.
  

• YARAHMADI, MONA: 3D Printing of Zirconia-based Ceramic Materials
  
  Author: YARAHMADI, MONA
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Normal
  Reading date: 26/05/2023
  Thesis director: FARGAS RIBAS, GEMMA | ROA ROVIRA, JOAN JOSEP
  

  Committee:
       PRESIDENT: FERRARI FERNÁNDEZ, BEGOÑA
       SECRETARI: JIMENEZ PIQUÉ, EMILIO
       VOCAL: TEJADO GARRIDO, ELENA MARÍA
  Thesis abstract: Zirconia stands out among oxide ceramics for its superior mechanical properties. This approach resulted from the significant research that has been conducted since the discovery of the tbughening capabilities of zitconia in the mid-1970s. Moreover, zirconia (ZrO2) is a ceramic material with good mechani.cal characteristics for medical deyice production. In this regard, zirconia stabilized with Y2O3 demonstrates the most suitable mechanical properties for these applications. A crystallographic transformation inhibits crack propagation when stress is applied. Additive manufacturing (AM) has been recognized as a type ofproficient manufacturing technologyfor building ceramic prototypes with increased dimensional accuracy, improved time efficiency, and reduced costsince itwas developed in the early 1980s. lt is a technique that is often based on 3D model files (CAD models) and layer-by-layer manufacturing.Many AM technologies have been developed for manufacturing various materials, such as metals and polymers, but only a few ofthem are appropriate for manufacturing ceramic products. Robocasting also called "Direct lnk Writing" (DIW), is an AM technology suitable for ceramic materiaIs developed to produce complex cerartlic parts. The method relies on a paste's extrusion that demonstrates shear-thinning behavior.In recent years, a significant investigation has been conducted to understand the fundamentals ofthe successful formation of zirconia ceramic parts manufactured by AM techniques and optimize the parts' performance. Despite the achievements, numerous challenges remain unaddressed, including porosity and cracks. which hinder the utilization ofthe DIW technique for zirconia fabrication parts.This thesis aim s to produce zirconia printed samples by DIW with the highest structural integrity and no geometric distortions. A novel approach is presented to evaluate the effect of Y2O3 content on the rheological properties of the ceram ic inks, printability, and mechanical integrityofprinted samples.lt is important to highlight that this work has also focused on the DIW of translucent zirconia to achieve full-density 3D zirconia parts where scarce information is found in the literature. Translucentzirconia is the newest preference ofzirconia-based ceramics, which aims to replace the non-transparent Yttria-stabilized Tetragonal Zirconia Pol rystal (Y-TZP) in more demanding aesthetic cases.This work is mainly developed using par,tially stabilized zirconia powder with 3 mol% Yttria (TZ-3YSB) and high-translucent zirconia grades: Zpex, Zpex-4, Zpex-smile, and TZ-8Ywith 3, 4, 5, and 8 mol% Yttria, respectively. The ink formulation is obtained from the mixture ofceramic powderwith h rogel, Pluronic® F-127.In the first section of the results, the study performed to determine the rheology of the considered ceramic inks (shear modulus and viscoelastic behavior) is shown; in the second section, the work carried outto optimize the parameters ofthe printing process by DIW and post-processing is exposed in order to obtain a dense three-dimensional structure. Finally, in the third section, the results derived from the microstructure analysis ofthe printed samples are presented, as well as the evaluation of their mechanical response through hardness, nanoindentation, scratch resistance, com pression resistance, and indentation fracture toughness.
  

• ZHANG, JUNHUI: Integration of sensors on 3D-printed Zirconia Ceramics to be Used in structural applications
  
  Author: ZHANG, JUNHUI
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Article-based thesis
  Reading date: 22/06/2023
  Thesis director: LLANES PITARCH, LUIS MIGUEL | FARGAS RIBAS, GEMMA
  

  Committee:
       PRESIDENT: SÁNCHEZ HERENCIA, ANTONIO JAVIER
       SECRETARI: SALAN BALLESTEROS, MARIA NURIA
       VOCAL: TORRES HERNANDEZ, YADIR
  Thesis abstract: Zirconia-based ceramics present unique combination of mechanical, thermal and chemical properties, making them a preferred choice in automotive, aerospace, heavy machinery, defence and healthcare sectors. However, manufacturing zirconia-based ceramic components still have significant production limitations when they involve complex shapes, micro-features or specific assemblages. Nowadays, 3D printing technologies enable adding up complex three­ dimensional structures with unique capabilities for increasing shape complexity and reducing waste material. Among the 3D printing techniques, direct ink writing (DIW) is often considered to yield fine and dense ceramic structures with geometrically complex morphology and high strength.In essence, a sensor is an object that detects events or changes in the environment and sends the corresponding real­ world data to an electronic device (e.g. a computer). Applications of sensors have been continuously increasing in many fields, such as manufacturing and machinery, aerospace and aeronautics, medicine and biomedical devices, and robotics, mainly due to the strong development of micro-machinery and advances in micro-controller platforms. In recent years, special attention has been paid to the use of 3D printing technology for the manufacturing of sensors. Through the 3D printing process, it is possible to embed a sensor into printed structures or intrinsically print the entire sensor. Considering different modern manufacturing processes, screen printing has proved its possibility with great potential for the fabrication of sensors and electronic components by printing conductive inks onto various rigid or flexible substrates. Screen printing is a simple, cost-effective and fast method.The assembly of advanced zirconia material with functions of sensing, actuation and controlling to solve the problems that may arise during its use is critical to ensure long-term service and performance. With advanced printing technologies, it is possible to print sensors on zirconia substrates, with the ability to sense surface displacement, temperature or pH.Within the above framework, the main goal of this thesis is to go one step forward and not only achieve 3D-printed dense zirconia parts with good structural integrity, but also monitor the potential initiation and propagation of defects in printed zirconia samples by introducing sensors capable of detecting them. The research effort focuses on three aspects: preparation of yttria-based zirconia (8Y-ZrO2) via direct ink writing, formulation of conductive inks for screen printing, and integration of sensors on 3D-printed zirconia substrates.
  

Last update: 04/10/2023 05:01:11.

Research groups

• BBT-Biomaterials, Biomechanics and Tissue Engineering
• CDAL-Light Alloys and Surface Treatment Design Centre
• CIEFMA-Structural Integrity, Micromechanics and Materials Reliability Centre
• e-PLASCOM-Eco-friendly Plastics and Composites
• InSup-Surface Interaction in Bioengineering and Materials Science Research Group
• POLY2-Polyfunctional polymeric materials
• PROCOMAME-Conformation Processes of Metallic Materials

Teachers

• Alcala Cabrelles, Jorge
• Arencon Osuna, David
• Baile Puig, Maria Teresa
• Benito Paramo, Josep Antoni
• Cabrera Marrero, Jose Maria
• Calvo Muñoz, Jesica
• Canal Barnils, Cristina
• de Redondo Realinho, Vera Cristina
• de Sousa Pais Antunes, Marcelo
• Engel Lopez, Elisabet
• Español Pons, Montserrat
• Fargas Ribas, Gemma
• Fernandez Aguado, Enrique
• Ginebra Molins, Maria Pau
• Jimenez Pique, Emilio
• Llanes Pitarch, Luis M.
• Manero Planella, Jose M.
• Martin Fuentes, Enric
• Mas Moruno, Carlos
• Maspoch Ruldua, Maria Lluïsa
• Mateo Garcia, Antonio
• Pegueroles Neyra, Marta
• Picas Barrachina, Josep A.
• Riera Colom, Maria Dolores
• Roa Rovira, Joan Josep
• Rodriguez Rius, Daniel
• Ruperez de Gracia, Elisa
• Sanchez Soto, Miguel Angel
• Santana Perez, Orlando
• Velasco Perero, Jose Ignacio

• Casellas Padro, Daniel