Ce travail s’intéresse a la synthèse et à la caractérisation de revêtements hybrides O/I à base de silice, préparés par voie sol-gel et déposés sur polycarbonate (PC), pour des applications en milieu chaud et humide dans le domaine culinaire. Le PC étant connu pour sa sensibilité à l’hydrolyse dans ce type de milieux (provoquant sa dépolymérisation progressive et ainsi la libération de bisphénol A, molécule suspectée comme étant toxique), le rôle du revêtement est donc de protéger le PC et d’éviter son vieillissement prématuré, tout en améliorant ses propriétés mécaniques. Dans un premier temps, de nombreux sols ont été synthétisés et optimisés, principalement en termes de nature et quantités de précurseurs, et de pH, dans le but d’obtenir des revêtements homogènes et transparents. Un suivi des réactions d’hydrolyse et de condensation des sols a également été réalisé afin de déterminer le temps minimal de maturation de ces derniers. Apres dépôt des revêtements par dip-coating, les propriétés mécaniques des films ont été étudiées par de nombreuses techniques. D’un point de vue général, les propriétés des échantillons revêtus ont été trouvées supérieures à celles du PC nu. L’influence de nombreux paramètres de synthèse comme le ratio organoalcoxysilane(s)/silice colloïdale, l’ajout d’additifs, le type de traitement de surface du PC pré-dépôt ou encore les conditions de recuit, a également été étudiée. L’ensemble de ce travail a permis d’obtenir, à partir de deux systèmes sol-gel différents, des revêtements performants en termes de transparence, d’adhésion au substrat, de non-toxicité, couplés à des valeurs élevées de dureté, de densité et de module de Young / This work deals with the synthesis and the characterization of hybrid O/I silica coatings prepared by the sol-gel route and deposited on polycarbonate (PC), for applications in hot and humid environment in the alimentary field. PC is well-known for undergoing hydrolysis in such conditions (causing its progressive depolymerization and thus leading to the release of bisphenol A, a molecule suspected to be toxic): the function of the coating would thus consist in preventing PC from this kind of premature ageing, along with the enhancement of its mechanical properties. As a first step, a lot of different sols were synthesized and optimized, mainly in terms of type and quantity of precursors, along with the pH, in order to obtain transparent and homogeneous coatings. The hydrolysis and condensation reactions were monitored in order to determine the minimum ageing time to be waited before any film deposition. After deposition by dip-coating, the mechanical properties of the films were assessed by using many different techniques. Basically, the coated-PC samples display higher properties than the uncoated one. The influence of numerous synthesis parameters such as the organoalkoxysilanes/colloidal silica ratio, the presence of additives, the kind of surface treatment of PC before film deposition, or the annealing conditions was also studied. This whole work led to the synthesis, from two different sol-gel systems, of superior quality coatings in terms of transparency, adherence to the substrate, non-toxicity, along with elevated hardness, density and Young’s modulus values

Submitted by Simone Maisonave (simonemaisonave@hotmail.com) on 2016-08-25T15:24:29Z No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Samantha Pinto da Silva_Dissertacao.pdf: 56289419 bytes, checksum: 62706bcba58770b81d3112a1917cb344 (MD5) Samantha Pinto da Silva_Produto da Dissertacao.pdf: 907566 bytes, checksum: 4b0014bf6eae7280cbadb421cf678398 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-08-25T16:55:46Z (GMT) No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Samantha Pinto da Silva_Dissertacao.pdf: 56289419 bytes, checksum: 62706bcba58770b81d3112a1917cb344 (MD5) Samantha Pinto da Silva_Produto da Dissertacao.pdf: 907566 bytes, checksum: 4b0014bf6eae7280cbadb421cf678398 (MD5) / Made available in DSpace on 2016-08-25T16:55:46Z (GMT). No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Samantha Pinto da Silva_Dissertacao.pdf: 56289419 bytes, checksum: 62706bcba58770b81d3112a1917cb344 (MD5) Samantha Pinto da Silva_Produto da Dissertacao.pdf: 907566 bytes, checksum: 4b0014bf6eae7280cbadb421cf678398 (MD5) Previous issue date: 2016-04-15 / Sem bolsa / Esta pesquisa tem como foco investigar como o uso da lógica de programação, mediada pela linguagem de programação Scratch, potencializa o ensino de Matemática quanto à resolução de problemas. Baseada em uma perspectiva sócioconstrutivista de mediação e colaboração, e na concepção de que o estudante de hoje é nativo no mundo digital, ambientado e interessado pelo uso desse tipo de tecnologia, realizou-se um estudo de caso com alunos do terceiro ano do Ensino Médio de uma escola pública estadual situada no município de Pelotas/RS. A coleta de dados aconteceu por meio de questionários mistos, teste de conhecimento e experimentações com o Scratch. Observou-se que a lógica de programação para a resolução de problemas e as atividades em grupo na criação de algoritmos, proporcionaram aulas mais dinâmicas e motivadoras à aprendizagem, nas quais os alunos demonstraram-se satisfeitos em aprender Matemática via Scratch. Além disso, percebeu-se que essa abordagem pode contribuir para o desenvolvimento de competências e habilidades necessárias à formação do estudante desta etapa escolar, desde que sua consolidação se dê em etapas anteriores. / This research investigate show the use of programming logic, through the programming language Scratch, optimizes the mathematics teaching process in terms of problems solving. Based on a socio-constructivist perspective of mediation and collaboration, it was conducted a case study with students of the last year of a state high school localized in the city of Pelotas/RS. This study takes into account the assumption that nowadays students are native in the digital world, accustomed and interested for this kind of technology. Data collection was made through mixed questionnaires, knowledge tests, and experiments with the Scratch. It was observed that the logic programming for the problems solving in addition to the group activity in the algorithms development allowed more dynamic and motivating classes. As result, students demonstrated being satisfied to learn mathematic through Scratch. Moreover, it was noted that this approach may contributes for the development of required skills in the training student process, if its consolidation be given in previous series.

Orientador: Petrilson Alan Pinheiro da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Estudos da Linguagem / Made available in DSpace on 2018-08-27T17:47:18Z (GMT). No. of bitstreams: 1 Ricarte_LidianyTeotonio_M.pdf: 11910318 bytes, checksum: bac8ea2ed96352e05b143c263e459c5f (MD5) Previous issue date: 2015 / Resumo: As discussões atuais sobre letramentos evidenciam que as práticas de leitura e produção textual contemporâneas dos alunos permeiam o uso das novas Tecnologias da Informação e da Comunicação (TICs) (LANKHEARS; KNOBEL, 2007; COPE; KALANTZIS, 2008; 2011). A Escola Municipal de Ensino Fundamental de Campinas, Estado de São Paulo, em que realizei a pesquisa, trabalha com as novas TICs, laptops distribuídos pelo Governo Federal por meio do Projeto Um Computador por Aluno (UCA), em sala de aula. Acompanhei uma sala do 5º ano (alunos de 09 a 10 anos) que tem o Projeto de Robótica em seu currículo e visa o ensino da programação em ferramentas digitais. Para a realização das atividades do projeto, a sala é dividida em 5 grupos e todos os alunos dispõem do laptop do UCA, do software livre Scratch, plataforma criada no Media Lab do MIT (Instituto de Tecnologia de Massachusetts) que possibilita a criação de animação e programação do robô , 5 kits de robótica e de internet de banda larga. O Projeto de Robótica foi realizado no período de março a setembro de 2013 e participei dele com o objetivo de analisar a apropriação da ferramenta Scratch pelos alunos na produção de animações, acompanhar o processo de aprendizagem com esta ferramenta e compreender como os alunos lidam com a questão dos multiletramentos, da multimodalidade, da autoria e do remix que ela propicia. As perguntas que surgiram durante a inserção no campo e que direcionaram a pesquisa foram as seguintes: i) Como as propiciações da ferramenta Scratch possibilitam repensar a questão da autoria, do remix e, de forma mais ampla, a produção textual no contexto escolar? ii) Como os alunos fazem uso da multimodalidade e dos recursos do Scratch e quais são os efeitos de suas escolhas na composição da animação e no processo de aprendizagem? O trabalho se insere na área da Linguística Aplicada e é um estudo de caso que se utiliza das seguintes ferramentas de pesquisa para geração de dados: a observação participante, diário de campo, vídeo-gravação das aulas e entrevista semiestruturada. Escolhi trabalhar com as produções de dois alunos para analisar o processo de criação da animação e o processo de aprendizagem com estes novos letramentos. O embasamento teórico centra-se na pedagogia dos multiletramentos (NLG, 1996; COPE; KALANTZIS, 2000; 2008) no conceito de "Web 2.0" (LANKSHEAR; KNOBEL, 2007; PINHEIRO, 2012), autoria (BARTHES, 1984; VAN HOECK; HOFFMAN, 2013) e remix (ERSTAD; GILJE; DE LANGE, 2007; MANOVICH, 2002). No dispositivo teórico-analítico do trabalho, mobilizei três conceitos trazidos por Bárbara Rogoff (2008 [1995]) para compreender o processo de aprendizagem do aluno com estes novos letramentos: aprendizagem, participação guiada e apropriação participativa, que a autora considera como conceitos inseparáveis que refletem diferentes planos de foco na atividade sociocultural: comunidade / institucional, interpessoal e pessoal. Por fim, notei que o Scratch, ambiente da Web 2.0 utilizado em sala de aula propiciou a criação de animações multimodais, remixadas e colaborativas no contexto escolar e possibilitou uma prática transformada / Abstract: The current discussions about literacies show that the students' contemporary reading and text production practices permeate the use of new Information and Communication Technologies (ICTs) (LANKHEARS; KNOBEL, 2007; COPE; KALANTZIS, 2008; 2011. The Municipal Elementary School of Campinas, in the State of São Paulo, where I performed the research, works with new ICTs - laptops distributed by the federal government through the project One Computer per Student (UCA) in the classroom. I worked with a 5th year classroom (students about 09-10 years old) that has the Robotics Project on its curriculum and aimes to teach programming in digital tools. To carry out the project activities, the room was divided into 5 groups and all students had the UCA's laptop, the free Scratch software, a platform created in the MIT Media Lab (Massachusetts Institute of Technology) that enables the creation of animation and programming of the robot, 5 robotics kits and broadband internet. The Robotics Project was carried out from March to September 2013 and I joined it aiming to analyze the appropriation of the Scratch tool by students in the production of animations and the issue of the learning process with this tool, in addition to understanding how students deal with the multiliteracies, multimodality, authorship and remix that it provides. The questions that arose during insertion in the field and directed the research were as follows: i) How the possibilities of the Scratch tool enables to rethink the question of authorship, the remix and, more broadly, textual production in the school context? ii) How students use multimodality and Scratch resources and what are the effects of their choices on the production of animation and in the learning process? The research is inserted in the area of Applied Linguistics and is a case study which uses the following research tools to generate data: participant observation, field diary, video recording of the classroom and semi-structured interview. I chose to work with two students productions to analyze the process of creating the animation and learning with these new literacies. The theoretical basis focuses on the pedagogy of multiliteracies (NLG, 1996; COPE; KALANTZIS, 2000; 2008), the concept of "Web 2.0" (LANKSHEAR; KNOBEL, 2007; PINHEIRO, 2012), authorship (BARTHES, 1984; VAN HOECK; HOFFMAN, 2013) and remix (ERSTAD; GILJE; DE LANGE, 2007; MANOVICH, 2002). In the theoretical and analytical device, I mobilized three concepts by Barbara Rogoff (2008 [1995]) to understand the student's learning process with these new literacies: participatory appropriation, guided participation and apprenticeship, which the author considers as inseparable concepts that reflect different focus plans on socio-cultural activities: community/institutional, interpersonal and personal. Finally, I observed that the Scratch, the Web 2.0 environment used in the classroom led to the creation of remixed and collaborative multimodal animations in the school context and enabled a transformed practice. OBSERVAÇÃOAs palavras Scratch e Remix devem ser grafadas em itálico / Mestrado / Linguagem e Educação / Mestra em Linguística Aplicada

Volgens die Kurrikulum- en Assesseringsbeleidsverklaring moet Inligtingstegnologie-leerders in graad 10 aanvangsonderrig in Scratch as programmeertaal ontvang en in graad 11 na Delphi of Java as programmeertaal oorskakel. In Noordwesprovinsie word Delphi as programmeertaal in graad 11 bestudeer. Die aard van Scratch en dié van Delphi verskil egter van mekaar. Scratch is ʼn visuele programmeertaal met ʼn speelse aard, waar boublokke met ingeboude programmeringskode inmekaar gepas word om programme te skep, terwyl programmeringskode in Delphi, onderhewig aan sintaktiese reëls, ingetik word. Daar word verder van leerders verwag om by Delphi ʼn objekgeoriënteerde programmeringsbenadering te volg terwyl Scratch as ʼn objekgebaseerde programmeertaal beskou word. Die oorgang vanaf Scratch na Delphi is nog nie tevore in navorsing ondersoek nie. Die doel van hierdie navorsing was dus om te bepaal hoe Scratch aan graad 10-leerders onderrig behoort te word om die oorgang na Delphi as sintaksisgebaseerde, objekgeoriënteerde programmeertaal te ondersteun. ʼn Kwalitatiewe studie is gedoen waartydens onderhoude met agt Inligtingstegnologie-onderwysers in Noordwesprovinsie gevoer is. Aan die begin van 2013 is die eerste onderhoude gevoer om te bepaal hoe Scratch in graad 10 onderrig is. Ná verloop van ses maande is ʼn tweede onderhoud met elke deelnemende onderwyser gevoer om te bepaal hoe die oorgang na Delphi in graad 11 ervaar is. Die bevindings dui daarop dat deelnemende onderwysers onseker was hoe om Scratch te onderrig en dat programmeringsbeginsels en -begrippe nie pertinent onderrig is nie. Onderwysers het op leerders se intuïtiewe begrip van programmeringsbegrippe staatgemaak en geskikte onderrig–leerstrategieë is nie toegepas nie. Met die oorgang na Delphi in graad 11 het onderwysers aangedui dat hulle programmering feitlik weer van voor af moes onderrig en dat baie min programmeringsbegrippe na Delphi oorgedra is. Onderwysers was onder druk om programmeringsbegrippe wat in graad 10 reeds vasgelê moes gewees het, tesame met nuwe begrippe wat vir die onderrig van Delphi benodig was, te onderrig. Voorstelle van onderwysers om toekomstige druk te verlig, het betrekking gehad op ʼn inkorting in Scratch-onderrigtyd en was nie gerig op die onderrig van programmeringsbeginsels en -begrippe in Scratch met die oog op die oorgang na Delphi nie. Tydens die navorsing is bevind dat die meeste programmeringsbeginsels en -begrippe reeds met Scratch onderrig kan word. Scratch-onderrig, met die oog op die oorgang na Delphi, moet egter noodwendig anders geskied as Scratch-onderrig ten einde ʼn belangstelling vir programmering te kweek. Na aanleiding van hierdie navorsing word aanbevelings gemaak om Scratch te onderrig, sodat die kennis en vaardighede wat graad 10-leerders met Scratch opdoen, verband hou en toegepas kan word op Delphi. Om onderwysers te ondersteun en hulle onsekerheid van Scratch-onderrig die hoof te bied, word spesifieke aanbevelings met betrekking tot die onderrig van Scratch gemaak ten opsigte van probleemvoorstelling en algoritme-ontwerp, instandhouding, foutopsporing en fouthantering, veranderlikes en datatipes, herhaling- en besluitnemingstrukture, objekgeoriënteerde begrippe, bewerkingsoperators, karakterhantering en ʼn onderrig–leerstrategieë vir Scratch. / MEd (Computer Science Education), North-West University, Potchefstroom Campus, 2015

Volgens die Kurrikulum- en Assesseringsbeleidsverklaring moet Inligtingstegnologie-leerders in graad 10 aanvangsonderrig in Scratch as programmeertaal ontvang en in graad 11 na Delphi of Java as programmeertaal oorskakel. In Noordwesprovinsie word Delphi as programmeertaal in graad 11 bestudeer. Die aard van Scratch en dié van Delphi verskil egter van mekaar. Scratch is ʼn visuele programmeertaal met ʼn speelse aard, waar boublokke met ingeboude programmeringskode inmekaar gepas word om programme te skep, terwyl programmeringskode in Delphi, onderhewig aan sintaktiese reëls, ingetik word. Daar word verder van leerders verwag om by Delphi ʼn objekgeoriënteerde programmeringsbenadering te volg terwyl Scratch as ʼn objekgebaseerde programmeertaal beskou word. Die oorgang vanaf Scratch na Delphi is nog nie tevore in navorsing ondersoek nie. Die doel van hierdie navorsing was dus om te bepaal hoe Scratch aan graad 10-leerders onderrig behoort te word om die oorgang na Delphi as sintaksisgebaseerde, objekgeoriënteerde programmeertaal te ondersteun. ʼn Kwalitatiewe studie is gedoen waartydens onderhoude met agt Inligtingstegnologie-onderwysers in Noordwesprovinsie gevoer is. Aan die begin van 2013 is die eerste onderhoude gevoer om te bepaal hoe Scratch in graad 10 onderrig is. Ná verloop van ses maande is ʼn tweede onderhoud met elke deelnemende onderwyser gevoer om te bepaal hoe die oorgang na Delphi in graad 11 ervaar is. Die bevindings dui daarop dat deelnemende onderwysers onseker was hoe om Scratch te onderrig en dat programmeringsbeginsels en -begrippe nie pertinent onderrig is nie. Onderwysers het op leerders se intuïtiewe begrip van programmeringsbegrippe staatgemaak en geskikte onderrig–leerstrategieë is nie toegepas nie. Met die oorgang na Delphi in graad 11 het onderwysers aangedui dat hulle programmering feitlik weer van voor af moes onderrig en dat baie min programmeringsbegrippe na Delphi oorgedra is. Onderwysers was onder druk om programmeringsbegrippe wat in graad 10 reeds vasgelê moes gewees het, tesame met nuwe begrippe wat vir die onderrig van Delphi benodig was, te onderrig. Voorstelle van onderwysers om toekomstige druk te verlig, het betrekking gehad op ʼn inkorting in Scratch-onderrigtyd en was nie gerig op die onderrig van programmeringsbeginsels en -begrippe in Scratch met die oog op die oorgang na Delphi nie. Tydens die navorsing is bevind dat die meeste programmeringsbeginsels en -begrippe reeds met Scratch onderrig kan word. Scratch-onderrig, met die oog op die oorgang na Delphi, moet egter noodwendig anders geskied as Scratch-onderrig ten einde ʼn belangstelling vir programmering te kweek. Na aanleiding van hierdie navorsing word aanbevelings gemaak om Scratch te onderrig, sodat die kennis en vaardighede wat graad 10-leerders met Scratch opdoen, verband hou en toegepas kan word op Delphi. Om onderwysers te ondersteun en hulle onsekerheid van Scratch-onderrig die hoof te bied, word spesifieke aanbevelings met betrekking tot die onderrig van Scratch gemaak ten opsigte van probleemvoorstelling en algoritme-ontwerp, instandhouding, foutopsporing en fouthantering, veranderlikes en datatipes, herhaling- en besluitnemingstrukture, objekgeoriënteerde begrippe, bewerkingsoperators, karakterhantering en ʼn onderrig–leerstrategieë vir Scratch. / MEd (Computer Science Education), North-West University, Potchefstroom Campus, 2015

TITLE: Teaching approaches to pupils' concept development about computer programming in SCRATCH AUTHOR: Bc. Hana Šandová DEPARTMENT: Department of information technology and education SUPERVISOR: Doc. RNDr. Miroslava Černochová, CSc. ABSTRACT: This thesis deals with perceptions of pupils about how computers and computer programs work. The main objective is to inquire of pupils (ISCED-2) about how computer and computer programs work, and what ideas influence them. The theoretical part focuses on the history of the use of computers in teaching and an analysis of current approaches to teaching computer science and programming in the Czech Republic and in selected European countries. The practical part is devoted to mapping concepts of pupils aged 11-14 years involved in a teaching experiment organized at two schools in Prague, the aim of which was to examine the impact of teaching programming in "Scratch" over one semester in relation to pupil's ideas about how a computer works and in terms of the development of pupil's computational thinking. KEYWORDS: pupil's imagination, algorithm, programming, computational thinking, Scratch

Lamellar graphite iron (LGI) is commonly used in diesel engine applications such as piston rings–cylinder liner where an excellent combination of physical and tribological properties is essential to avoid scuffing and bore polishing issues. The excellent tribological behaviour of LGI alloys is related to the graphite lamellas, which act as solid lubricant agents by feeding onto the tribosurfaces under sliding conditions. However, increasingly tighter emissions and fuel economy legislations and the higher demands on enhanced power and durability have encouraged both engine designers and manufacturers to introduce pearlitic compacted graphite irons (CGI) as an alternative material replacing LGI, although the poor machinability of pearlitic CGI alloys compared to the LGI remains a challenge. The focus of this study is placed on investigating how the microstructure of LGI and CGI alloys affects their mechanical and tribological properties. This was initially undertaken by investigating representative, worn lamellar cast iron piston rings taken from a two-stroke large-bore heavy-duty diesel engine. As known that it is tribologically essential to keep the graphite open under sliding conditions, in particular under starved lubrication regimes or unlubricated conditions to avoid scuffing issues; however, this study revealed the closure of a majority of graphite lamellas; profoundly for those lamellas that were parallel to sliding direction; due to the severe matrix deformation caused by abrasion. Both microindentation and microscratch testing, which were used to crudely simulate the abrasion under starved lubricated condition in combustion chamber, suggested a novel mechanism of activating the graphite lamellas to serve as lubricating agents in which the matrix deformation adjacent to the graphite initially resulted in fracturing and then extrusion of the graphite lamellas. Additionally, in order to investigate the relation between matrix constituents, mechanical properties and machinability of cast iron materials, solution-strengthened CGI alloys were produced with different levels of silicon and section thicknesses. The results showed significant improvements in mechanical properties and machinability while deteriorating the ductility. Moreover, multiple regression analysis, based on chemical composition and microstructural characteristics was used to model the local mechanical properties of high Si ferritic CGI alloys, followed by implementing the derived models into a casting process simulation which enables the local mechanical properties of castings with complex geometries. Very good agreement was observed between the measured and predicted microstructure and mechanical properties.

Ce travail de thèse contribue à étudier le comportement élasto-plastique au rayage du verre métallique massif Zr55Cu30Al10Ni5 par la méthode des éléments finis (MEF) et expérimentaux. Le critère de plasticité de type Drucker-Prager est utilisé, une méthode de remaillage est proposée afin d'éviter le problème de convergence qui vient de la grand contrainte cisaillement. Pour cela, le comportement au rayage est étudié par le changement de l'angle d'attaque, du coefficient de frottement local entre le matériau et l'indenteur. Ces influences sont valorisés par l'évolution des forces rayures, par la morphologie de l'échantillon, et ils montrent le mécanisme de changement des modes de rayage : du labourage à l'usinage avec la formation des copeaux. Les essais sont réalisés à l'aide de l'équipement du LARMAUR : Un nano-triboindenteur de type Hysitron Ti-950. La comparaison des résultats simulés et expérimentaux nous permettre d'évaluer la loi comportement utilisé et d'estimer la valeur de coefficient de frottement entre le matériau et l'indenteur. / This thesis contributes to modeling of the elasto-plastic behavior in scratch test of a Zr55Cu30Al10Ni5 Bulk Metallic Glasses (BMG) by the finite element method and by experimental testing. The Drucker-Prager criterion is used and dedicated re-meshing method is proposed in order to solve the numerical problems classically encountered when modeling such a test and this with a controlled element population. The influence of friction coefficient as well as the angle of attack are investigated to understand the occurrence of two deformation mechanisms : plowing and cutting. The test is realized by using the LARMAUR's equipment : nano triboindenter Hysitron Ti-950. The result of experimental and simulation are confronted the finite element simulations.

Aluminium is one of the metals playing a prominent role in automobile industry after cast iron. Because of its light weight property and good mechanical properties. When aluminium reinforced with silicon carbide showing good tribological properties and improved strength. Aluminium silicon carbide needs some good wear and frictional properties to use it as break disc. Aluminium reinforced with 15% and 20% silicon carbide and casted in two different ways, liquid casting and stir casting. Four different composites are compared in this paper. Hardness test was carried out on the samples. Increase in the Vickers hardness with increase in silicon carbide reinforcement for both the castings is observed. Rockwell C hardness is showing decreasing trend with increase in SiC reinforcement. The scratch resistance of the surface under micro level was analysed with the help of nano scratch test. The SiC particles in the aluminium matrix are resisting the indenter from deep deformation of the surface. Frictional forces are dropped whenever the indenter met the SiC particles. In other cases, SiC particles are deforming the aluminium matrix in the form of broken particles. The plastic deformation of aluminium is observed, and material is piled up on sideways of groove at high load.Sliding wear behaviour of the composites are investigated by means of reciprocating pin on plate wear rig. The test was carried out at load of 20N for five different sliding duration. Aluminium with 20% silicon carbide of liquid casting is used as a base metal. The worn-out surface of the samples is analysed in SEM. The metallography of the worn-out samples is showing some deep grooves and abrasion of the material. Wear debris from both the surfaces are forming into a cluster of layers. These layers are protecting the surface from wear in some areas were observed. Composition of tribo layer formed during the test was investigated with the help of EDS analysis. The tribo layer are rich in aluminium and silicon elements because both the samples are made of aluminium silicon carbide.

Made available in DSpace on 2016-04-27T14:31:24Z (GMT). No. of bitstreams: 1 Angelo Costa dos Santos.pdf: 1014845 bytes, checksum: 6c0b2e0c4daf12a0b1797d87cd46b814 (MD5) Previous issue date: 2014-07-30 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / This study aims to investigate the relevance of authorship Scratch language in formal learning context, identifying their contributions and limitations by analyzing three masters dissertations (Marques, 2009; OLIVEIRA, 2009 and Pinto, 2010). To achieve the goals and objectives, this study has a methodological basis bibliographic research with qualitative approach. The search performed on databases of theses and dissertations had the time interval between 2007 and 2014, aiming to establish an overview of academic publications on the subject of study. The systematic organization of information, process of pre-selection and selective reading, enabled the creation of three categories of analysis (autonomy, problem solving and logical reasoning), that stood out in terms Interpretation of researchers throughout our analysis process. The interpretation and analysis results show that the authoring language allows Scratch to create more meaningful student learning strategies. Among the researchers was identified convergence of dialogue in this sense, however, they conclude that the language itself does not guarantee the student to go further in their learning process, without the mediation of a teacher. In this case, it is believed that the debate around the use of this language in education must remain open, enabling further discussion about its relevance in education / Este estudo investiga a relevância da linguagem de autoria Scratch em contexto formal de aprendizagem, identificando suas contribuições e limitações através da análise de três dissertações de mestrado (MARQUES, 2009; OLIVEIRA, 2009 e PINTO, 2010). Para alcançar os objetivos gerais e específicos, este trabalho tem como base metodológica a pesquisa bibliográfica com abordagem qualitativa. O processo de busca realizado em bancos de teses e dissertações teve como recorte temporal o intervalo entre 2007 e 2014, com o objetivo de estabelecer uma visão geral acerca das publicações acadêmicas sobre o objeto de estudo. A organização sistemática de informações, processo de pré-seleção e leitura seletiva, possibilitaram a criação de três categorias de análise (autonomia, resolução de problemas e raciocínio lógico), termos que se destacavam na intepretação dos pesquisadores ao longo do nosso processo de análise. A interpretação e análise de resultados evidenciam que a linguagem de autoria Scratch possibilita ao educando criar estratégias de aprendizagem mais significativas. Entre os pesquisadores foi identificada convergência de diálogo neste sentido, porém, os mesmos concluem que a linguagem por si só não garante ao aluno chegar mais longe em seu processo de aprendizagem, sem a mediação de um professor. Neste caso, acredita-se que o debate em torno do uso desta linguagem na educação deve permanecer aberto, possibilitando novas discussões sobre sua relevância na educação