[pt] A presente dissertação sob o título de O ser humano, um ser de relação: a Ecologia Integral como caminho de reintegração e reconciliação, busca adentrar o campo da antropologia teológica tendo como inspiração maior a Encíclica Laudato Si. Nela o Papa Francisco nos apresenta os grandes impactos da crise socioambiental que atravessamos e alternativas para seu enfrentamento. Essa crise é também uma crise de humanidade, visto que a partir da modernidade com o surgimento do paradigma tecnocrático, houve uma mudança profunda na compreensão do ser humano que influenciou diretamente na forma com que ele estabelece seus vínculos. Ao se autodeclarar senhor, dominador e explorador da natureza por meio do aparato técnico, o ser humano vai pouco a pouco se distanciando da sua própria identidade e integralidade e seus relacionamentos passam a ser marcados pela superficialidade, pelo individualismo e pela falta de gratuidade. Ao colocarmos em evidência o conceito de Ecologia Integral queremos evocá-lo como um novo paradigma que substitua o tecnocrático. Um paradigma que efetive um processo de reumanização, onde o ser humano supere todo e qualquer dualismo e se reintegre enquanto pessoa. Além disso, certos de que o ser humano, é por natureza, um ser de relação, urge uma restauração de seus vínculos com Deus, com seus pares e com a natureza como uma espécie de movimento de reconciliação. Reconstruir o ser humano hoje é fundamental para pensarmos na existência futura da humanidade sobre a terra. / [en] The current dissertation under title The human being, a being of relationship: the Integral Ecology as reintegration and reconciliation path, as the objective to go into the teological antropology having as most inspiration the Laudato Si Encyclical. In the encyclical Pope Francis presents us the big impacts of socio-environmental crisis we are through and the alternatives to face it. This crisis is also a humanity crisis, seen from of the modernity with showing up of tecnocratical paradigm, there was a deep change in the human being comprehension that influenced directly on the way it is stablished its relationships. When self declaring lord, dominator and explorer of nature using technical apparatus, the human being goes litle by litle distancing of its own identity and completeness and its relationship become marked by superficiality, individualism and by lack of gratuity. When we bring the concecpt of Integral Ecology we want to evoke it as new paradigm to replace the technocratical. A paradigm that effective a rehumanization process where human being overcome all and any dualism and self reinteger as person. Besides, we are sure human being, is by nature, a being of relationship, urge its relationship restoration with God, with its pairs and with nature such as reconcialiation movement. Rebuild the human being today is fundamental for us to think future existence of humanity on earth.

[pt] A contribuição do papa Francisco para o diálogo inter-religioso, em especial na sua carta encíclica Laudato Si’ é o tema principal desta dissertação. Foi feita uma exposição sobre o tema do diálogo inter-religioso em geral, através de obras de referência para esta temática, a fim de compreender os desafios e a importância do diálogo em tempos de pluralismo religioso e crise sócio-ecológica. Assim, foi preparado o terreno para posicionarmos as contribuições do papa Francisco ao tema do diálogo inter-religioso, caracterizando sua atuação em prol do diálogo da fraternidade, na amizade e caminhada conjunta, que vai em busca do enriquecimento mútuo e bem comum, trabalhando em favor da paz, justiça social, tolerância e liberdade religiosa. Utilizou-se primeiramente como base a exortação apostólica Evangelii Gaudium, conteúdo programático de seu pontificado que prevê a prática do diálogo inter-religioso como parte da missão evangelizadora da Igreja Católica. Chegou-se ao entendimento de que o diálogo inter-religioso está dentro da prática pastoral de Francisco. Levantou-se então a pergunta-hipótese: há em Francisco uma contribuição original e singular para o tema do diálogo inter-religioso atual? Questão respondida positivamente. Através da análise da Laudato Si, constatou-se uma contribuição original de Francisco para a temática do diálogo inter-religioso, a construção de uma ecologia integral como tema de reflexão, encontro e colaboração inter-religiosas. Esta pesquisa integra-se no Projeto de Pesquisa sobre a Laudato Si coordenado pela professora orientadora. / [en] Pope Francis contribution to interreligious dialogue, especially through his encyclical letter Laudato Si, is the main theme of this dissertation. A presentation on the theme of interreligious dialogue in general was made, through reference works on this theme, in order to understand the challenges and importance of dialogue in times of religious pluralism and socio-ecological crisis. Thus, the ground was prepared to position Pope Francis contributions to the theme of interreligious dialogue, characterizing his action in favor of the dialogue of fraternity, in friendship and joint journey, which seeks the mutual enrichment and common good, working for peace, social justice, tolerance and religious freedom. The apostolic exhortation Evangelii Gaudium was first used as a basis, the programmatic content of his pontificate which foresees the practice of interreligious dialogue as part of the evangelizing mission of the Catholic Church. The understanding was reached that interreligious dialogue is within Francis s pastoral practice. The hypothesis question then arose: is there in Francis an original and singular contribution to the theme of current interreligious dialogue? Question answered positively. Through the analysis of Laudato Si, it was found an original contribution of Francis to the theme of interreligious dialogue, the construction of an integral ecology as a theme of interreligious reflection, encounter and collaboration. This research is part of the Laudato Si Research Project, coordinated by the research advisor teacher of this dissertation.

High-pressure die casting of semi-solid aluminium-silicon alloys is used in the automotive industry to manufacture components, like housings, brackets, and bars. It is commonly known that during high-pressure die casting, defect bands may be created that follow the contour of the component surface. These bands consist mainly of a eutectic phase. This phenomenon is also observed in semi-solid metal slurry high-pressure die casting. These bands could lead to premature failure of the component in service. The origin of these bands is not fully understood and so this research focuses on investigating these bands and their origins further. A series of casting trials were conducted with varying plunger velocity. Subsequent investigation using optical and scanning electron microscopy showed that a change of the plunger velocity alters the number of bands present in the samples. Energy dispersive X-ray spectroscopy revealed that a measurable difference in aluminium quantity across the band was noticed and it was postulated that aluminium migrates towards the component centre. Therefore, different mechanisms responsible for particle migrations found in literature were investigated and assessed quantitatively using experimental data and information from published literature. It was found that the Saffman lift force and the Mukai-Lin-Laplace effect were the mechanisms that were most likely to cause such a migration of aluminium. Further experimental investigation is recommended to identify which of the two mechanisms is ultimately responsible for the migration and to optimise the high-pressure die casting procedure to minimise defect band formation. / Produktion av högtrycksgjutning av halvfasta aluminium-kisellegeringar används i fordonsindustrin för att tillverka komponenter, som exempel till kåpor, konsoler och stag. Det är allmänt känt att defektband kan formas under högtrycksgjutning som följer konturen av komponentytan. Dessa band består huvudsakligen av eutektisk fas. Detta fenomen har också observerats vid högtrycksgjutning produktion av halvfast slurry. Potentiellt kan dessa band leda till en försämring av komponentens mekaniska egenskaper och resultera i ett förtida brott. Ursprunget av dessa band är inte helt kartlagda och det är därför viktigt att fokusera ytterligare på denna forskning och att undersöka dessa band och deras ursprung. En serie med gjutningsförsök genomfördes med varierande kolvhastighet. Efterföljande undersökning med optisk- och svepelektronmikroskopi visade att en förändring av kolvhastigheten förändrar antalet band som finns i proverna. Energidispersiv röntgenspektroskopi avslöjade en mätbar skillnad i aluminiumkvantitet över bandet, och det antogs att aluminium migrerar mot centrum av komponenten. Därför undersöktes och utvärderades olika mekanismer som ansvarar för partikelmigrationer som finns att finna i litteratur med hjälp av experimentella data och information från publicerad litteratur. Det visade sig att Saffman lyftkraft och Mukai-Lin-Laplace effekten var de mekanismer som mest troligen orsakade migration av aluminium. Ytterligare experimentella försök rekommenderas för att identifiera vilken av dessa två mekanismerna som i slutändan är ansvarig för migrationen. Detta för att optimera gjutningsprocessen och därmed minimera uppkomsten av defektband.

[pt] Esta pesquisa procura esclarecer os princípios fundamentais que a Escola de Arquitetura e Design da Pontifícia Universidade Católica de Valparaíso, Chile, vem trabalhando ao longo de sua trajetória, centrando-se nos conceitos de observação e ato de observação, entendidos estes como elementos fundamentais de um processo de transmissão de ferramentas disciplinares e, ao mesmo tempo, como elementos do processo formativo que esta escola propõe. A suposição que se formula nesta pesquisa é que subjacente a estes conceitos encontramos os componentes que permitem esclarecer as dimensões que conformam o ethos da escola, que se funda na relação estabelecida entre arquitetura e poesia, segundo a orientação artística por ela sustentada. Tratamos então de identificar aqueles elementos constitutivos do ethos que assim se evidencia, para então adentrarmos e elucidarmos o ethos que supomos subjacente, e que buscamos na produção discursiva da escola, na transmissão oral, nos textos fundamentais e especialmente no exercício de suas práticas, enfim naquilo que é próprio de seu processo formativo, e que possibilita revelar aqueles aspectos que para esta pesquisa permitem esclarecer um modo de relação entre a disciplina do design e o ethos que a anima. Relação essa, segundo se propõe aqui, fundada na práxis de um modo e ver a realidade, a observação, permeada por isso que chamamos aqui de um ethos subjacente, gerado nos efeitos que essa mesma práxis da observação suscita. Trata-se aqui portanto do tema da formação do Homem, digamos de uma ética humanista de formação, tema próprio da modernidade, que esta pesquisa propõe confrontar com uma perspectiva contemporânea, à luz de uma ética de formação de sujeitos. A questão que está em jogo aqui é a tentativa de elucidar em que medida este ethos, que supomos subjacente às práticas e aos discursos da escola, pode ser aproximado das considerações de Foucault a propósito do ethos grego formulado nos preceitos do cuidado de si, e em que medida este cuidado de si pode ser entendido como um elemento fundamental para a formulação do ethos que esta escola constrói. Esta busca de um modelo de formação próprio desenvolvido por essa escola se enraíza em uma genealogia de pistas filosóficas encontradas em seus fundamentos, tanto explícitos como não explicitados. Se esta escola se funda na busca de um olhar próprio (seu sentido de originalidade), desde o estabelecimento de uma linguagem para a formação de um olhar próprio do sujeito, como podemos conceber para ela um modo de formação que atenda às exigências acadêmicas contemporâneas para reencontrar o sentido de uma formação de sujeitos? E, desde esta perspectiva, o que seria então a observação? Porque supomos que o ato de observação propicia a transmissão do ethos desta escola? / [en] This research will try to clarify the fundamental principles that the School of Architecture and Design of the Pontificia Universidad Católica de Valparaiso, Chile, has worked throughout its development, focusing on the concepts of observation and observation, understood as fundamental elements of A process of transmission of disciplinary tools and at the same time, as elements of the formative process that this school proposes. The assumption that emerges from this research is that these concepts underlie the components that allow us to clarify the dimensions that make up the ethos of the school, which we assume is based on the relation architecture - poetry, artistic orientation that this school supports. We will then try to identify those constituent elements of the ethos that are evidenced, in order to delve in and elucidate the underlying ethos, which we can assume present in the discursive elements that this school unfolds, being oral transmission, fundamental texts and especially The exercise of its practices, that which as part of its training process, will reveal or make it possible to reveal those aspects that for this research allow to clarify a way of relating between design discipline and the ethos that animates it, which is assumed here, founded In the praxis of a way of seeing reality, the observation and that is now faced with another look, which in the words of this research we call as an underlying ethos, generated from the same sense that the exercise of the praxis of Observation provokes. We then deal with the formation of Men, let us say of a humanist ethic of forming men, a subject characteristic of modernity, but, apparently of this research, it becomes necessary to proceed with another vision, to put it in question with another perspective Contemporary, let us say, in the light of an ethics to form subjects. The question at stake here is to elucidate the extent to which this supposedly underlying ethos corresponds to a look that approximates Foucault s proposal for the Greek ethos, since the e (ad) generates a clear Approach to the Greek way that Foucault points out as care of itself and this as a fundamental element for the conformation of the ethos that this school builds. This search for a model of own formation that this school develops, finds roots in a heap of philosophical foundations, for that reason, it is believed then, that one must attend to these foundations, both explicit and not explicit. If this school is founded on the search for its own look (its sense of originality), that is, from the establishment of a language for the formation of a look of the subject, how can we conceive a way of training that attends to the Contemporary needs to rediscover the meaning of a formation of subjects? And in this perspective, what then is the observation? And why do we suppose there is an act of observation that allows such transmission of the ethos of this school? / [es] Esta investigación tratará de clarificar los principios fundamentales que la escuela de Arquitectura y Diseño de la Pontificia Universidad Católica de Valparaíso, Chile, ha trabajado a lo largo de su desarrollo, centrándose en los conceptos de observación y acto de observación entendidos estos como elementos fundamentales de un proceso de transmisión de herramientas disciplinares y a la vez, como elementos del proceso formativo que esta escuela propone. El supuesto que se desprende de esta investigación es que en estos conceptos subyacen los componentes que permiten esclarecer las dimensiones que conforman el ethos de la escuela, lo que suponemos tiene su fundamento en la relación arquitectura – poesía, orientación artística que esta escuela sostiene. Trataremos entonces de identificar aquellos elementos constituyentes del ethos que se evidencia, para desde allí adentrarnos y dilucidar el ethos que suponemos subyacente, que lo podemos suponer presente en los elementos discursivos que esta escuela despliega, siendo la transmisión oral, los textos fundamentales y en especial el ejercicio de sus prácticas, aquello que como propio de su proceso formativo, revelará o hará posible revelar aquellos aspectos que para esta investigación permitan clarificar un modo de relación entre disciplina del diseño y el ethos que la anima, la que se supone aquí, fundada en la praxis de un modo de ver “la realidad”, la observación y que queda ahora enfrentada a otra mirada, la que al decir de esta investigación llamamos como un ethos subyacente, generado desde ese mismo sentido que el ejercicio de la praxis de la observación provoca. Tratamos entonces el tema de la formación de Hombres, digamos de una ética humanista de formar hombres, tema propio de la modernidad, pero, que al parecer de esta investigación, se hace necesario discurrir con otra visión, ello para ponerla en cuestión con otra perspectiva contemporánea, digamos, a la luz de una ética para formar sujetos. La cuestión aquí en juego es dilucidar en qué medida este ethos supuesto como subyacente, corresponde a una mirada que se aproxima a la propuesta de Foucault a propósito del ethos griego, ello, por cuanto la e(ad) genera en su devenir, una clara aproximación al modo griego que Foucault señala como cuidado de si y este como un elemento fundamental para la conformación del ethos que esta escuela construye. Esta búsqueda de un modelo de formación propio que esta escuela desarrolla, encuentra raíces en un cumulo de fundamentaciones filosóficas, por ello, se cree entonces, que se debe atender a esos fundamentos, tanto explícitos como no explicitados. Si esta escuela se funda en la búsqueda de una propia mirada (su sentido de originalidad), es decir, desde el establecimiento de un lenguaje para la formación de una mirada propia del sujeto, ¿Cómo podemos concebir un modo de formación que atienda à las necesidades contemporáneas para reencontrar el sentido de una formación de sujetos? Y en esta perspectiva, ¿Qué es entonces la observación? y ¿Por qué suponemos existe un acto de observación que permite tal transmisión de del ethos de esta escuela?

[pt] A tese que se apresenta com o título Ecologia e tecnocracia: a ressignificação do kérigma cristão à luz do diálogo com Hans Jonas é, sobretudo, um trabalho de teologia pastoral que se inspirou na Encíclica Laudato Si do Papa Francisco, que lança uma grave preocupação cósmica e humana. Humana-cósmica porque coloca o grave problema ecológico que a humanidade enfrenta diante das catástrofes naturais e talvez diante de um fim do planeta. Pastoral porque se a Igreja prega novos céus e nova terra, então, fica impossível este anúncio diante do possível fracasso do cosmos destruído pelo sistema econômico, sustentado por uma filosofia que pretende tirar do depósito ilimitado da natureza toda sua riqueza. Como pregar um final feliz em que Deus seja tudo em todo, diante da iminencia da catástrofe final? Esta pergunta decisiva foi colocada em outra perspectiva por Hans Jonas, quem procurou oferecer uma resposta ética e teológica a partir da responsabilidade e da teopatia. A obra de Hans Jonas, que, aliás, contesta a gnose, atravessará esta tese para permitir concluir que uma escatologia cristã sem uma responsabilidade que salve o cosmos, assumindo a dor de Deus é impossível, mesmo dentro de uma visão cristã a partir de Cristo morto na cruz e ressuscitado. Essa responsabilidade é um chamado que toca à humanidade toda, a todas as religiões e aos sistemas econômicos. Isso vai permitir um diálogo frutuoso com o pensamento, com as teologias e especialmente com os pobres, principais vítimas do problema ecológico. Esse diálogo deve levar a uma mística que contemple, na alteridade, o problema de maneira antropocósmica. É um novo falar de Deus. / [en] The thesis presented with the title Ecology and technocracy: the resignification of Christian kerigma in the light of dialogue with Hans Jonas is above all a work of pastoral theology inspired by Pope Francis Encyclical Laudato Si, which casts grave concern. human and cosmic. Cosmic-human because it poses the serious ecological problem facing humanity in the face of natural disasters and perhaps an end to the planet. Pastoral because if the Church preaches new heavens and a new earth, then this announcement becomes impossible in the face of the possible failure of the cosmos destroyed by the economic system, supported by a philosophy that seeks to take from its unlimited deposit all its richness. How can we preach a happy ending in which God is all in all in the face of the imminent catastrophe? This decisive question was put in another perspective by Hans Jonas, who aimed to provide an ethical and theological answer from responsibility and theopathy. Hans Jonas s work, which incidentally contests gnosis, will cross this thesis to allow us to conclude that a Christian eschatology without a responsibility that saves the cosmos, assuming the pain of God is impossible, even within a Christian vision from Christ dead in Christ, cross and risen. This responsibility is a call that touches all humanity, all religions, and economic systems. This will allow fruitful dialogue with thought, theologies and especially the poor, who are the main victims of the ecological problem. This dialogue must lead to a mystique that contemplates the problem in anthropocosmic way in otherness. It is a new talk of God.

[pt] Este trabalho apresenta a relação entre esperança e responsabilidade. Relação que aparece como força dinamizadora atuando nos processos de libertação, criando espaços de transformação no meio ambiente e na história, já que o ser humano se encontra subjugado por processos econômicos e mercadológicos de desenvolvimento que, ao invés de gerarem vida, acabam produzindo um sistema de opressão e morte. A pesquisa segue uma metodologia bibliográfica em três partes, primeiro abordando a problemática do mundo atual e suas consequências para o futuro do planeta e da humanidade. Disserta sobre como a existência humana e toda a criação é colocada em perigo pelo descaso do próprio ser humano, esquecido de ser ele também parte da criação. Trata da relação entre o ser humano e a natureza, apontando o descaso ao priorizar a técnica e a produção, promovendo um olhar a natureza de forma utilitarista. Na segunda parte, são relacionadas a responsabilidade e a esperança, mostrando sua importância para a transformação da realidade, revelando ser a esperança responsável e força motriz na construção de um mundo novo, do Reino de Deus, projeto divino de salvação. Na terceira parte, apresenta-se como essa esperança é gerada, como pode ser caminho de discernimento para uma verdadeira transformação da realidade, gerando um mundo mais justo, solidário e humano, com a possibilidade de produzir um olhar crítico e construtivo para a realidade, despertando o desejo de criar um mundo novo, tocado pela esperança e marcado pela responsabilidade, mundo do Reino de Deus instaurado por Jesus de Nazaré. / [en] This paper aims to present the relationship between hope and responsibility. A relationship that appears to originate a driving force that can act in the liberation processes, creating spaces of transformation in our environment and history, since the human being is overwhelmed by economic and market development processes that, instead of generating life, produce a system of oppression and death. Our research follows a bibliographic method in three parts. First, we will deal with the problems of the present world and the consequences for the future of the planet and humanity. We will talk about how human existence and all creation is endangered by the neglect of the human being, forgetting that he is also part of creation. We will deal with the relationship between human beings and nature, pointing out neglect while prioritizing technique and production, given the utilitarian perception of nature. In the second part we will relate responsibility and hope showing its importance for the transformation of reality. We will present hope, the driving force in the construction of a new world, the Kingdom of God, divine project of salvation. In the third part, we will talk about how hope is generated and can be a way of discernment for a true transformation of reality, generating a more just, supportive and humane world, enabling a critical and constructive look at reality and awakening the desire to create a new world touched by hope and responsibility, a world of the Kingdom of God established by Jesus of Nazareth.

[pt] O tema da Senhora Pobreza, abraçado por São Francisco, e o tema da Sobriedade Feliz, indicado na encíclica do Papa Francisco, Laudato Si , são estudados na espiritualidade franciscana, com origens na história medieval, na Regra Franciscana e um conjunto de documentos papais, junto da Laudato Si . Esses temas são importantes não só para o bem da Igreja, mas também para o mundo contemporâneo e para as gerações futuras. O objetivo principal é destacar o importante legado deixado por São Francisco, a sua compreensão da pobreza evangélica e apreciar sua relevância. Deste estudo, destacam-se os seguintes pontos: a pobreza evangélica se reflete na questão da aquisição de bens e na pastoral desenvolvida em diferentes lugares do mundo onde a presença franciscana é vista em ação; a relação entre a pobreza evangélica vivida por São Francisco e os ensinamentos do Papa Francisco. A metodologia implementada incluiu uma seleção de obras pertinentes ao tema, a análise desses textos, a comparação dos principais pontos relativos à espiritualidade e à pastoral, a constatação de eventuais continuidades e a compreensão de como a espiritualidade franciscana reacende e pode ajudar na busca por valores ou pode ser sustentada com o papado de Francisco. Os vários documentos e mensagens publicados pelo papa refletem a sua direção para uma Igreja pobre e preocupada com os mais necessitados, seguindo o projeto que vem de Jesus Cristo. Este projeto encontra-se no documento Laudato Si, e fala das preocupações socioambientais e da resposta do ser humano que pode alcançar vivendo uma vida de sobriedade feliz. A tese também contribui para apresentar uma melhor compreensão da Senhora Pobreza. A pobreza evangélica, seguida por São Francisco de Assis, é analisada e se baseia em diversos textos do Antigo e do Novo Testamento. A pesquisa inclui comentários de vários franciscanos que propiciam uma melhor compreensão sobre o tema e permitem entender o legado da pobreza, servindo como tecitura entre as ideias de São Francisco e do Papa Francisco. Concluindo, este estudo deduz que há uma continuidade entre a pobreza da Igreja evangélica, abraçada por São Francisco de Assis – a Senhora Pobreza –, e a Laudato Si na conversão de valores para uma vida de sobriedade feliz. O estudo aprofundado confirma que os temas considerados são importantes hoje em relação ao evangelho, especialmente para os jovens, em termos de busca de uma vida melhor, que em essência seria uma vida com sobriedade feliz / [en] The theme of Lady Poverty, embraced by Saint Francis, and the theme of Happy Sobriety, indicated in Pope Francis encyclical, Laudato Si, are studied through the Franciscan spirituality, with origins in medieval history, the Franciscan Rule, and a set of papal documents, alongside Laudato Si. These themes are important not only for the good of the Church but also for the contemporary world and for future generations. The primary objective is to highlight the important legacy left by Saint Francis, his understanding of evangelical poverty and to appreciate its relevance. From this study, the following points are relevant for consideration: evangelical poverty is reflected in the matter of acquiring goods and in the pastoral care developed in different places around the world where the Franciscan presence is seen at work; the relationship between evangelical poverty experienced by Saint Francis and the teachings of Pope. The methodology implemented included a selection of works relevant to the topic, the analyzation of these texts, the comparison of the main points regarding spirituality and pastoral care, the noting of any continuities and the understanding of how Franciscan spirituality rekindles and can help in the search for values or can be sustained with the papacy of Pope Francis. During his pontificate, Pope Francis released several documents and messages that reflect his direction of a poor Church that is concerned about those in most need. It follows the project that comes from Jesus Christ. This project is found in the document Laudato Si, and speaks of socio-environmental concerns, and the response of human beings living a life of happy sobriety. Moreover, the thesis also contributes to presenting a better understanding of Lady Poverty. In addition, evangelical poverty, followed by St. Francis of Assisi, is analyzed, and is based on several texts from the Old Testament and the New Testament. The thesis includes commentaries from several Franciscans that help us understand the developed legacy of poverty and serves as a legacy of continuity between the idea of Saint Francis and Pope Francis and texts from Pope Francis that serve as pathways for young people. In conclusion, this study deduces that there is a continuity between evangelical church poverty, embraced by Saint Francis of Assisi – Lady Poverty –and Laudato Si and the conversion of values with a life of happy sobriety. The indepth study confirms that the themes considered are important today in relation to the gospel, particularly for young people, in terms of searching for a better life, which in an essence would be a life with happy sobriety.

The development of molybdenum - silicon - boron (Mo-Si-B) composites having a combination of high temperature strength, creep, and oxidation residence has the potential to substantially increase the efficiency of gas turbines. The refractory nature of the αMo, Mo3Si (A15), and Mo5SiB2 (T2) phases results in good strength and creep resistance up to 1300°C. At this temperature, the formation of a borosilicate surface scale from the two intermetallic phases is able to provide oxidation resistance. However, realization of these advantages has been prevented by both a high brittle to ductile transition temperature and difficulty in forming the initial surface borosilicate to provide bulk oxidation resistance. This dissertation addresses two factors pertaining to this material system: 1) improvements to powder processing techniques, and 2) development of compositions for oxidation resistance at 1300°C. The processing of Mo-Si-B composites is strongly tied to their mechanical properties by establishing the αMo matrix, limiting impurity content, and reducing silicon supersaturation. These microstructural aspects control the brittle to ductile transition temperature which has traditionally been too high for implementation of Mo-Si-B composites. The processing here built upon the previously developed powder processing with silicon and boron nitrides which allowed for a low oxygen content and sintering of fine starting powders. Adjustments were made to the firing cycle based upon dew point measurements made during the hydrogen de-oxidation stage. Under a relatively high gas flow rate, 90% of the total water generated occurred during a ramp of 2°C /min between 450 and 800°C followed by a hold of 30 minutes. The oxidation resistance of Mo-Si-B composites was studied for a wide range of compositions. Silicon to boron atomic ratios were varied from 1 to 5 and iron, nickel, cobalt, yttria, and manganese were included as minor additions. In all these compositions, the αMo volume fraction was kept over 50% to ensure the potential toughness of the composite. For the oxidized surface glass, a silica fraction of 80 to 85% was found to be necessary for the borosilicate to have a sufficiently high viscosity and low oxygen permeability for oxidation resistance at 1300°C. For the Mo-Si-B bulk composition this corresponds to a Si/B atomic ration of 2 to 2.5. Higher viscosity compositions failed due to spallation of poorly attached, high silica scales. Lower viscosity compositions failed from continuous oxidation, either through open channels or repetitive MoO3 bubble growth and popping. Additionally, around 1% manganese was necessary for initial spreading of the borosilicate at 1300°C. In conjunction with flowing air to prevent MoO3 accumulation, oxidation weight loss rates below 0.05 mg/cm2-hr were measured. Finally, a theory is proposed here to describe the mechanisms responsible for the development of oxidation resistance. This theory involves three stages associated with: 1) generation of an initial surface borosilicate, 2) thickening of the borosilicate layer, and 3) slow parabolic oxidation controlled by the high silica surface scale.

Aluminium castings with a large grain structure have poor mechanical properties which are primarily due to casting defects as opposed to fine grain structure. The grain refinement practice using chemical addition is well established for wrought alloys, however in the case of casting alloys, the practice of adding grain refiners and the impact on castability is not well established. The addition of well known Al-5Ti-B grain refiner to casting alloys with silicon (Si) content above 3 wt.% is not effective. This is believed to be due to the chemical reaction between Ti and Si. The current research aim is to find an alternative, but effective, chemical phase which can refine Al-Si alloy grains. Based on a crystallographic database search and intermetallic phases found in Aluminium–Niobium-Boron, there exists several iso-structural phases similar to those of Al3Ti and TiB2. We have selected a phase which exhibits chemical phase stability with Si (below 900 oC) and developed a potential novel grain refiner Nb-B for Al-Si cast alloys. Various Al-Si binary alloys and a commercial sourced LM6 (Al-10Si-Mg) cast alloys were cast after novel grain refiner addition to the melt. It is the first time that such fine grain structures were achieved for Al-Si alloys when Si >4wt.%. It is believed that Nb-B grain refiner enhances the heterogeneous nuclei in the melt. The effectiveness of this grain refiner under various cooling rate conditions is investigated to simulate various practical casting conditions. Due to increased heterogeneous nuclei density, a fine grain structure is also obtained at low cooling rates and the grain size is less sensitive to the cooling rate. The processing of high Si containing alloys for complex shaped castings with reduced defects, fine grain structure and improved mechanical properties are now possible.

Thesis (PhD (Physics))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Silicon/silicon dioxide (Si/SiO2) interface is widely used in microelectronics as the gate between the drain and source of most metal oxide semiconductor field effect transistors (MOSFETs). The functionality, reliability and electrical properties of such transistors are strongly dependent on the quality of the Si/SiO2 structure forming the gate. Characterization of the Si/SiO2 interface is important in understanding device degradation therefore the Si/SiO2 interface is a subject of intensive investigation. Research studies of Si/SiO2 interfaces using optical methods have been reported by many groups around the world but to date many open questions still exist. The physics of photoinduced trap or defect generation processes and the subsequent trapping of charge carriers, the precise role of photoinduced interfacial electric field in altering optical properties of the Si/SiO2 interface and its role in affecting the second harmonic (SH) yield measurements are not well understood. In this work a commercial near infrared femtosecond (fs) laser source [1.55 eV, 75 ± 5 fs, 10 nJ, 80 MHz] is used to study native Si/SiO2 interfaces of free standing single crystalline Si membrane and bulk Si. Optical second harmonic (SH) generated at the Si/SiO2 interfaces of a Si membrane in reflection and for the first time in transmission is demonstrated as well as stationary, single colour, pump-probe reflectivity measurements from the Si/SiO2 interface of bulk n-type Si. The experimental setups for the second harmonic generation (SHG) and pump-probe techniques were designed and implemented, and measurements were recorded by a computer controlled data acquisition system. Free standing Si membrane samples were successfully produced at the Institut f¨ur Photonische Technologien (IPHT) in Jena, Germany from bulk Si using a chemical etching process and were characterised using the z-scan technique. The penetration depth of light with a photon energy of 1.55 eV in silicon allows transmission of the fundamental fs laser pulses through the Si membrane (∼ 10 μm in thickness) and this is exploited to generate a SH signal in transmission from the Si/SiO2 interfaces of the Si membrane. In the presence of sufficiently intense fs laser light defects are created at the interfaces and populated by multiphoton transfer of charges from Si to SiO2 where they are subsequently trapped. The transfer of charge establishes interfacial electric fields across the interfaces of the Si membrane and this enhances SHG. This phenomenon is called electric field induced second harmonic (EFISH) generation. To our knowledge, EFISH measurements from interfaces of Si membrane performed in transmission are demonstrated for the first time in the present study. The demonstration of EFISH in transmission revealed new results which allowed us to provide additional perspectives on the EFISH generation process at Si/SiO2 interfaces never reported before. The temporal response of SH signals from virgin spots were recorded at different incident laser powers for both reflection and transmission geometries. The SH responses measured in transmission were observed to be time dependent and show an increase during irradiation of the sample corresponding to EFISH process. A series of SH measurements were recorded at different laser powers to compare the magnitudes of SH yield in each detection geometry for a single Si/SiO2 interface. The magnitude of the SH yield measured in transmission was higher than expected and surpassed the SH yield measured in reflection. The expectation is based on the fact that the local intensity of the fundamental beam at the second interface where the SH in transmission is generated is low compared to the local intensity at the first interface where the SH in reflection originates. A physical model is developed to consistently interpret the experimental results obtained in this study. In this model we established the origin of EFISH signals in each detection geometry, explain the unexpected high SH signals measured in transmission and provide an analysis of the time constants extracted from SH response in transmission and reflection. In addition, we also report for the first time stationary pump-probe reflectivity measurements from bulk n-type Si(111) samples with native oxide. A strong pump beam was focused on the same spot as a weak probe beam from the same fs laser source. The change in reflectivity of the Si(111)/SiO2 system was recorded by monitoring the change in intensity of the weak reflected probe beam. The temporal evolutions of the reflectivity of the material were recorded at different pump powers. The reflectivity of the material increases over several minutes of irradiation and reaches steady-state after long time irradiation. The change in reflectivity of the material is attributed to a nonlinear process called Kerr effect, and the temporal response arises from the photoinduced interfacial electric field across the Si(111)/SiO2 interface caused by multiphoton charge transfer from bulk Si(111) to the SiO2 layer. The results reported in this study contribute to the understanding of the photoinduced interfacial electric field caused by charge carrier separation across buried solid-solid interfaces. They also reveal nonlinear optical processes such as the Kerr effect caused by charge dynamics across the interface in addition to the well known SHG process. / AFRIKAANSE OPSOMMING: Die silikon/silikon dioksied (Si/SiO2) skeidingsvlak word algemeen gebruik in mikro-elektronika as die hek tussen die put en die bron van die meeste metaaloksied halfgeleier veld-effek transistors (MOSFETs). Die werkverrigting, betroubaarheid en elektriese eienskappe van sulke transistors word grootliks bepaal deur die kwaliteit van die Si/SiO2 struktuur wat die hek vorm. Karakterisering van die Si/SiO2 skeidingsvlak is belangrik om die degradering van die transistor te verstaan en daarom is die Si/SiO2 skeidingsvlak die onderwerp van intensiewe ondersoek. Ondersoek van die Si/SiO2 skeidingsvlak deur van optiese metodes gebruik te maak is geraporteer deur verskeie internasionale groepe, maar daar bestaan tot vandag toe nog n groot aantal onbeantwoorde vrae. Die fisika van die fotogenduseerde generering van defekte en van posisies waarin ladings gevang kan word, asook die daaropvolgende vasvang van ladingsdraers, die presiese rol van die fotoge¨ınduseerde elektriese veld oor die skeidingsvlak in die verandering van die optiese eienskappe van die Si/SiO2 skeidingsvlak en die grootte van die tweede harmoniek (SH) sein word nog nie goed verstaan nie. In hierdie werk word n kommersile naby-infrarooi femtosekonde (fs) laserbron [1.55 eV, 75 ± 5 fs, 10 nJ, 80 MHz] gebruik om natuurlike Si/SiO2 skeidingsvlakke van vrystaande enkelkristallyne Si membrane en soliede Si te bestudeer. Optiese tweede harmoniek (SH) wat by die Si/SiO2 skeidingsvlakke van ’n Si membraan gegenereer word - in refleksie en vir die eerste keer in transmissie - is gedemonstreer, asook stasionˆere, een-golflengte pomp-toets refleksiemetings op die Si/SiO2 skeidingsvlak van soliede n-gedoteerde Si. Die eksperimentele opstellings vir die tweede harmoniek generering (SHG) en pomp-toets tegnieke is ontwerp en uitgevoer en metings is opgeneem deur ’n rekenaarbeheerde dataversamelingstelsel. Vrystaande Si membraan monsters is suksesvol by die Institut f¨ur Photonische Technologien (IPHT) in Jena, Duitsland vervaardig uit soliede Si deur ’n chemiese etsproses en is gekarakteriseer met behulp van die z-skanderingstegniek as deel van hierdie studie. Die diepte waartoe lig met ’n fotonenergie van 1.55 eV in silikon indring laat die transmissie van die fundamentele fs laserpulse deur die Si membraan (met ∼ 10 μm dikte) toe en dit word ontgin om ’n SH sein van die Si/SiO2 skeidingsvlakke van die Si membraan in transmissie te meet. In die teenwoordigheid van fs laserlig met voldoende intensiteit word defekte by die skeidingsvlakke geskep en bevolk deur meer-foton ladingsoordrag van die Si na die SiO2 waar die ladings daaropvolgens vasgevang word. Die oordrag van ladings skep elektriese velde oor die skeidingsvlakke van die Si membraan en dit versterk die SHG. Hierdie verskynsel word elektriese veld ge¨ınduseerde tweede harmoniek (EFISH) generering genoem. Sover ons kennis strek is die meting van EFISH seine van skeidingsvlakke van Si membrane in transmissie vir die eerste keer in hierdie studie gedemonstreer. Die demonstrasie van EFISH in transmissie het nuwe resultate opgelewer wat ons toegelaat het om bykomende perspektiewe op die EFISH genereringsproses by Si/SiO2 skeidingsvlakke te verskaf waaroor nog nooit vantevore verslag gedoen is nie. Die tydafhanklike gedrag van die SH seine van voorheen onbestraalde posisies is gemeet by verskillende drywings van die inkomende laserbundel vir beide die refleksie en transmissie geometrie¨e. Die gedrag van die SH sein in transmissie is waargeneem om tydafhanklik te wees en ’n toename te toon gedurende bestraling van die monster in ooreenstemming met EFISH prosesse. ’n Reeks van SH metings is opgeneem by verskillende laserdrywings om die groottes van die SH opbrengste in elke meetgeometrie vir ’n enkele Si/SiO2 skeidingsvlak te vergelyk. Die grootte van die SH opbrengs wat in transmissie gemeet is was ho¨er as verwag is en het die grootte van die SH opbrengs in refleksie oortref. Die verwagting is gebaseer op die feit dat die lokale intensiteit by die tweede skeidingsvlak waar SH in transmisie gegenereer word relatief laag is in vergelyking met die lokale intensiteit by die eerste skeidingsvlak waar SH in refleksie ontstaan. ’n Fisiese model is ontwikkel om die eksperimentele resultate wat in hierdie studie verkry is op ’n konsekwente wyse te interpreteer. In hierdie model het ons die oorsprong van EFISH seine in elke meetgeometrie vasgestel, die onverwagte ho¨e SH seine wat in transmissie gemeet is verklaar en ’n analise van die tydkonstantes wat uit die SH gedrag in transmissie en refleksie afgelei is gedoen. Verder rapporteer ons ook vir die eerste keer stasionˆere pomp-toets reflektiwiteitsmetings van soliede n-gedoteerde Si(111) monsters met ’n natuurlike oksied. ’n Sterk pompbundel is gefokus op dieselfde posisie as ’n swak toetsbundel van dieselfde laserbron. Die verandering in reflektiwiteit van die Si(111)/SiO2 stelsel is gemeet deur die verandering in die intensiteit van die swak weerkaatste toetsbundel te monitor. Die tydevolusie van die reflektiwiteit van die mate riaal is gemeet by verskillende pompdrywings. Die reflektiwiteit van die materiaal neem toe gedurende etlike minute van bestraling en bereik ’n stasionˆere toestand na ’n lang tyd van bestraling. Die verandering in reflektiwiteit van die materiaal word toegeskryf aan ’n nielini ˆere prosess, naamlik die Kerr effek, en die tydafhanklike gedrag ontstaan as gevolg van die fotoge¨ınduseerde elektriese veld oor die Si(111)/SiO2 skeidingsvlak wat veroorsaak word deur meer-foton ladingsoordrag van die soliede Si(111) na die SiO2 laag. Die resultate wat in hierdie studie gerapporteer word dra by tot die verstaan van die fotoge ¨ınduseerde elektriese veld oor die skeidingsvlak wat veroorsaak word deur die skeiding van ladingsdraers oor die bedekte kristal-kristal skeidingsvlak. Dit lˆe ook nie-liniˆere optiese prosesse soos die Kerr effek bloot wat veroorsaak word deur die dinamika van ladings oor die skeidingsvlak, bykomend tot die bekende SHG proses.