Polyetheretherketone (PEEK) is a designation given to materials of the polyaryletherketone family having a characteristic distribution of ether and ketone groups in the polymer backbone. PEEK materials have high strength and chemical resistance as well as very high melting points and glass transition temperatures. Because of this combination of properties, PEEK materials find use for wear application in extreme environments where they provide a light-weight and corrosion resistant bearing material that often does not require lubrication. An initial study focused on determining the effects of supplier and molecular weight on the wear of particular PEEK materials, in addition to the effect of contact pressure. This work is significant because it highlights the fact that tribologically relevant polymers, such as PEEK materials, vary greatly in terms of their polymer morphology and processing history, and this variation must be recognized by investigators when reporting wear data. Because of their light weight, chemical resistance, and self-lubricating properties, polymers are used in applications ranging from biomedical to aerospace. Some polymers exhibit significant differences in wear resistance based on whether they are in unidirectional or multidirectional sliding. Shear induced polymer chain orientation is believed to be responsible for this behavior. Polyetheretherketone (PEEK) has excellent wear resistance, but its multidirectional sliding behavior has not been thoroughly investigated. A factorial multidirectional pin-on-plate wear study of PEEK was conducted with a focus on molecular weight and sliding path directionality. These factors were studied for their correlation to overall wear performance. Additionally, transfer film thickness was measured at locations along the wear path using white light interferometry. A result of this work has been a greater understanding of PEEK wear mechanisms in various sliding configurations and how they relate to transfer film formation. A major outcome was the development of a quantitative metric to describe transfer film thickness and continuity. It was found that thinner more continuous transfer films form under sliding conditions that change direction rather than overlapping along the same path. The thinner more continuous transfer film was found to also correspond with statistically lower wear behavior. Scanning electron microscope (SEM) investigation of the transfer film and pin wear surface confirmed the relationship between transfer film quality and wear.

This study seeks to unpack the formation mechanisms of social innovation (SI) initiatives in Cuernavaca, Mexico. Subsequently, this study employs a qualitative case study to investigate (1) local embedding, (2) trans-local connectivity and (3) university linkages of SI initiatives in Cuernavaca. Previous research indicated that socio-spatial dynamics are critical for the development of SI initiatives. Furthermore, previous research asserted that universities are imperative to SI in the context of Latin America. Nevertheless, previous research contemplating the formation mechanisms of SI was primarily western- centric and displayed an inadequacy to acknowledge SI in the context of Latin America. Based on previous research this study presents a theoretical framework that classifies the results in eight typologies based on (1) local embedding, (2) trans-local connectivity and (3) university linkages. All three dimension are classified as either "high" or "low", which grants insights into influential formation mechanisms. Subsequently, a sample of n=10 SI initiatives was compiled and twelve semi-structured interviews with representatives of the SI initiatives were conducted. The results indicate three typologies of SI initiatives. Five SI initiatives were classified as: HLH – high local embedding, low trans-local connectivity, and high university linkages. Four initiatives were classified as: LHH – low local embedding, high trans-local connectivity, and high university linkages. One initiative was classified as HLL – high local embedding, low trans-local connectivity, low university linkages. The results indicate that SI initiatives either seek to address local challenges or direct their efforts to trans-local challenges. Furthermore, universities evidently play a critical role in the formation of SI initiatives in Cuernavaca and Mexico. This study contributes to SI literature by presenting evidence that universities possess critical roles in the formation of SI. Future research should increasingly embed universities into theoretical approaches when investigating SI formation mechanism in Latin America.

L’énergie photovoltaïque jouera un rôle déterminant dans la transition énergétique future. Bien que les cellules solaires à base de silicium dominent encore le marché, leur coût de fabrication et le poids des modules limitent leur développement. Depuis quelques années, les industriels s’intéressent de plus en plus aux dispositifs à base de couches minces en raison de leurs procédés de fabrication rapides et peu onéreux sur de larges substrats. Cette technologie utilise une large variété de matériaux; les chalcopyrites tels que Cu(In,Ga)Se2 sont les plus prometteurs. Le procédé de fabrication de couches chalcopyrites le plus répandu est la coévaporation mais l’utilisation de vides très poussés rende cette technique peu adaptée à la production à grande échelle de modules bon marché. La solution alternative décrite dans ce travail est un procédé en deux étapes basé sur le recuit sous atmosphère réactive de précurseurs métalliques électrodéposés. Le développement de cette technologie passe par une meilleure compréhension des mécanismes d’incorporation et d’homogénéisation du gallium dans les couches formées et par une optimisation des étapes de recuit. Le premier objectif de ce travail de thèse est une étude des mécanismes réactionnels mis en jeu lors du procédé de recuit à travers l’étude de différents types de précurseur. Par la suite ces connaissances sont utilisées pour modéliser et optimiser un recuit industriel innovant. Ce travail est réalisé à l’aide de plans d’expérience (DOE) où l’influence de certains paramètres, les plus critiques est mise en évidence. Des voies d’optimisation sont proposées et des hypothèses faites afin d’expliquer les phénomènes observés. / Solar energy is promised to be a major actor in the future of energy production. Even if silicon based solar cells remain the main product their fabrication is energy consuming and requires heavy cover glass for protection, which reduce their development. For several years, commercial interest has shifted towards thin-film cells for which manufacturing time, large scale production, fabrication costs and weight savings are the main advantages. For thin film technology, a wide variety of materials can be used but chalcopyrite such as Cu(In,Ga)Se2 is one of the most promising. The most current method used for chalcopyrite formation is co- evaporation but this process is very expensive and not well suitable for large scale production due to high vacuum requirements. One alternative solution described in this work consists of a two-step technology based on the sequential electro-deposition of a metallic precursor followed by a rapid reactive annealing. However to reach its full potential this technology needs a better understanding of the Ga incorporation mechanism and of the selenization/sulfurization step. This work focuses first on formation mechanisms through the study of several kinds of precursor. This knowledge is then used to explain and to optimize innovative annealing processes. This study is achieved by observing the impact of some process parameters using designs of experiment (DOE). A link between process parameters and properties of these thin films is obtained using electrical, structural and diffusion characterization of the devices. Finally we propose hypothesis to explain observed phenomena and also some improvements to meet the challenges of this process.

Les procédés de projection thermique permettent de fabriquer des revêtements d’une grande versatilité (métaux, céramiques, polymères ou autres composites), relativement épais (de quelques microns à plusieurs centimètres) avec une vitesse de dépôt relativement importante. Cependant des contraintes existent notamment l’impossibilité d’utiliser des précurseurs à fusion non congruente tels que les nitrures (TiN par exemple) limitant leur application industrielle (aéronautique, énergie, biomédical, etc.). Ce type de revêtement est principalement obtenu par les procédés couches minces. La projection plasma sous très basse pression (VLPPS) ouvre un potentiel pour s’affranchir de cette problématique d’obtenir des revêtements nitrures et présente en plus l’avantage d’avoir des vitesses de dépôt élevées au contraire des procédés couche mince. Pour cela, la phase liquide habituellement créée par l’injection de la poudre dans la source thermique des procédés de projection peut s’élever à l’état de vapeur du fait des conditions de très basse pression. En conséquence, des revêtements denses à microstructure lamellaire, de vapeurs condensées ou mixte sont formés. Mais encore, le matériau à l’état vapeur peut être mis en contact avec un gaz réactif (azote, oxygène, etc.) pour former un composé nitruré, oxydé.Ce travail a consisté à étudier la réalisation de revêtements céramiques oxydes et nitrures par projection plasma sous très basse pression réactive (R-VLPPS) à partir d’une poudre pure de titane. Tout d’abord, le diagnostic du jet plasma sous très basse pression (gaz plasmagène et réactif, précurseur) a été réalisé dans le but de corréler la présence des espèces détectés avec les propriétés des revêtements. Ainsi, des revêtements de nitrure et d’oxyde de titane ont été fabriqués par R-VLPPS. Les paramètres de réalisation des dépôts (distance de projection, méthode d’injection du gaz réactif) ont été analysées. Les caractéristiques mécaniques des compositions obtenues ont été déterminées. Le jet plasma a aussi été testé comme moyen de post traitement pour améliorer la proportion de phases nitrurées ou oxydées. Enfin, le mécanisme de construction des revêtements a été développé à partir des résultats expérimentaux. / Thermal spraying processes allow the manufacturing of high versatility coatings (metals, ceramics, polymers or other composites), relatively thick (from few microns to several centimeters) with a high deposition rate. However, drawbacks exist in particular the impossibility to use non-congruent fusion precursors such as nitrides (TiN for example) limiting their industrial application (aeronautics, energy, biomedical, etc.). This kind of coating is mainly obtained by thin-film processes. Very low-pressure plasma spraying (VLPPS) opens a potential to overcome this problem to obtain nitride/oxide/carbide coatings with high deposition rates unlike thin-film processes. For this purpose, the liquid phase usually generated by the particles injection into the thermal source of the spray jet can rise to the vapor state due to the conditions of the very low pressure. As a result, dense coatings with a lamellar, condensed vapors or a mix of both microstructures are manufactured. Furthermore, a reactive gas (nitrogen, oxygen, etc.) can be injected with the vapors to form oxide, nitride materials.This work consisted in studying the fabrication of oxides and nitrides ceramic coatings by reactive - very low-pressure plasma spraying (R-VLPPS) from a pure powder of titanium. Firstly, the diagnostic of the plasma jet under very low pressure (plasma and reactive gases, precursor) was carried out with the aim of correlating the presence of the detected species with the properties of the coatings. Titanium nitrides and oxides coatings were manufactured by R-VLPPS. The spraying parameters of the deposits (spraying distance, reactive gas injection method) were analyzed. The composition and the mechanical characteristics of the coatings are determined. Moreover, the plasma jet has also been tested as post-treatment process to improve the amount of nitrided or oxidized phases. Finally, the manufacturing mechanism of the coatings was developed from the experimental results.

For the EU to reach its 2050 climate targets the aviation industry that is highly dependent on fossil fuels needs to drastically reduce its emissions. In the decarbonisation of the aviation industry drop-in sustainable aviation fuels (SAFs) have been identified as a promising solution to abate the industry’s emissions. To increase the adoption of SAFs, The EU has announced a proposal called ReFuelEU Aviation, introducing obligated blend mandates for SAFs that airlines and fuel suppliers need to comply with, starting at 2% in 2025 going up to 70% by 2050. A subset of SAFs called electrofuels, made from green hydrogen and carbon dioxide, could become essential in the sustainability transition with an emission abatement potential of up to 95% compared to fossil jet fuel. However, there exist no large scale production of electrofuels and previous research suggests that they will be several times more expensive to produce than their fossil counterparts, highlighting that the production and adoption will be challenging. In this thesis we first study how and under which conditions electrofuel value chains can develop in Sweden and second to which extend locally-produced electrofuels may be economically feasible. The former was studied qualitatively and the latter quantitatively, which together identified challenges and opportunities for electrofuels to decarbonise the aviation industry. The qualitative analysis was researched by conducting semi-structured interviews with industry actors, researching the current policy landscape and analysing the findings from a theoretical lens of ‘complementarity formation mechanisms in technology value chains’. The quantitative analysis was researched by a techno-economic assessment of e-kerosene production in Sweden using an alkaline electrolyser, different carbon capture technologies and a Fischer Tropsch fuel synthesis. In the qualitative analysis we found, in contrast to previous research, that the incremental cost associated with adoption of electrofuels is not necessarily the greatest concern. Instead, the value chain development of electrofuels is dependent on synchronised development of the input sectors renewable energy, hydrogen production and carbon capture technologies. Industry actors may not invest in large scale electrofuel production until they have secured a supply for renewable energy. There is also a liability of limited scalability in these, affected by slow permit processes and construction of new renewable energy, risking that electrofuels are not produced sustainably and at a high cost. We also found that producing bio-electrofuels, utilising lignocellulosic biomass from e.g., forest residue, can become important for Swedish fuel production. In the quantitative analysis the results show a levelised cost of e-kerosene of 3.8-6.1 times higher than the fossil jet fuel price of April 2023, sensitive to changes in energy price and capital expenditures of electrolysers for hydrogen production. We also found that the source of carbon capture affects the price, where direct air capture (DAC) increased total costs by 32% and 25% compared to bioethanol and pulp and paper, respectively. The levelised cost yield emission abatement costs between 457-1,042 €/tonne CO2e, depending on energy scenario and emissions abatement potential. In conclusion, we have found that the production of electrofuels for aviation is contingent on low energy prices, point-source carbon capture and economies of scale in hydrogen production. This highlights that renewable energy in combination with technological developments in hydrogen and carbon production is essential to establish a sustainable value chain. This can become challenging as other industries, such as green steel, will require similar inputs for production, emphasising that the location of electrofuel plants highly impacts the business case and possibility to produce relatively sustainable and cost competitive products. / För att EU ska nå sina klimatmål för 2050 behöver flygindustrin, som är beroende av fossila bränslen, drastiskt minska sina utsläpp. I dekarboniseringen av flygindustrin har hållbara flygbränslen (SAF) identifierats som en potentiell lösning för att minska utsläppen i industrin. EU har tagit fram förslaget ReFuelEU Aviation som inför obligatoriska inblandningskrav av SAF för flygbolag och bränsleleverantörer, med start 2025 på 2% och en ökning till 70% fram till år 2050. En subkategori av SAF kallade elektrobränslen, som tillverkas av grön vätgas och koldioxid, kan bli avgörande i hållbarhetsomställningen med en potential att reducera utsläpp med upp till 95% jämfört med fossilt flygbränsle. Samtidigt finns det idag ingen storskalig produktion av elektrobränslen och forskare och branschexperter tror att produktionskostnaderna kommer att vara flera gånger dyrare än den fossila motsvarigheten, vilket antyder att produktionen av elektrobränslen kommer medföra utmaningar. I denna uppsats studerar vi först hur och under vilka förutsättningar elektrobränsle-värdekedjor kan utvecklas i Sverige, och sedan under vilka förutsättningar produktion av elektrobränslen kan vara ekonomiskt konkurrenskraftigt. Den första frågeställningen studerades kvalitativt och den andra kvantitativt, vilka tillsammans identifierade utmaningar och möjligheter för produktion och användning av elektrobränslen för att dekarbonisera flygindustrin. Den kvalitativa analysen bestod av semistrukturerade intervjuer med aktörer inom branschen och forskning kring det nuvarande policylandskapet. Dessa resultat analyserades sedan utifrån en teoretisk lins av ’komplementära formationsmekanismer i teknologiska värdekedjor’. Den kvantitativa delen analyserades genom en tekno-ekonomisk analys av e-fotogenproduktion i Sverige genom en alkalisk elektrolysör, olika tekniker för koldioxidavskiljning och bränslesyntes via Fischer-Tropsch. I den kvalitativa analysen fann vi, i motsats till tidigare forskning, att de inkrementella kostnaderna för införandet av elektrobränslen inte nödvändigtvis är det största hindret. I stället är utvecklingen av elektrobränsle-värdekedjor beroende av en synkroniserad utveckling av förnybar energi, vätgasproduktion och koldioxidavskiljningstekniker då industriella aktörer kan vara motvilliga att investera i storskalig elektrobränsleproduktion innan de har en säkrat tillgång av förnybar energi. Det finns också en risk för begränsad skalbarhet på grund av långsamma tillståndsprocesser för konstruktion av ny förnybar energi, vilket kan leda till att elektrobränslen inte produceras hållbart och till höga kostnader. Vi fann också att produktion av bio-elektrobränslen, genom att använda lignocellulistisk biomassa från exempelvis skogsrester, kan bli viktigt för den svenska bränsleproduktionen. I den kvantitativa analysen visade resultaten att kostnaden för e-fotogen är 3.8-6.1 gånger högre än den fossila motsvarigheten och att priset var känsligt mot förändringar i energipris och investeringskostnader för elektrolysören för vätgasproduktion. Vi fann också att källan till koldioxidavskiljning påverkar priset, där direktluftsavskiljning (DAC) ökade de totala kostnaderna med 32% respektive 25% jämfört med bioetanol och pappersmassa. Produktionskostnaderna för elektrobränslen indikerarar en utsläppsminskningskostnad mellan 457-1,042 €/ton CO2e, beroende på energiscenario och utsläppsminskningspotential. Slutsatsen är att produktionen av elektrobränslen för flygindustrin är beroende av låga energipriser, källa för koldioxidavskiljning och stordriftsfördelar för vätgasproduktion. Detta påvisar att förnybar energi i kombination med teknologisk utveckling inom vätgas- och koldioxidproduktion är avgörande för att etablera en välfungerande värdekedja. Detta kan bli utmanande då andra industrier, som produktionen av grönt stål, kommer att kräva liknande insatsvaror för produktion och betonar därmed vikten av den geografiska placeringen av elektrobränslefabriker för att ha möjligheten att producera hållbara och kostnadseffektiva bränslen.