Esse trabalho teve como objetivo analisar a influência da temperatura de revenimento na tenacidade à fratura dinâmica e na tenacidade à fratura assistida pelo ambiente de um aço inoxidável martensítico AISI 420. Para realização do tratamento térmico de revenimento as temperaturas de 380 e 540ºC foram selecionadas, sendo que esta última situa-se dentro da faixa de fragilização ao revenido desse material. Todos os ensaios reproduzidos neste trabalho foram realizados à temperatura ambiente utilizando corpos de prova da mecânica da fratura do tipo SE(B). As análises dos resultados obtidos mostraram uma grande susceptibilidade desse aço à fragilização ao revenido, inclusive com a mudança dos micromecanismos de fratura envolvidos no processo de falha, quando exposto ao ambiente de água do mar sintética sob proteção catódica de - 1100mVECS e a condições dinâmicas de carregamento, onde observou-se, respectivamente, uma redução na ordem de 60% e 30% do valor de tenacidade à fratura do material. / This study aimed to analyze the influence of tempering temperature on dynamic toughness and environment toughness of a stainless steel AISI 420. To carry out this study the tempering temperatures of 380 and 540ºC were selected, with the last one being within the range of the embrittlement of this material. All tests reproduced in this work were performed at room temperature on specimens of the mechanical fracture SE (B). The analysis of the obtained results showed a great susceptibility of this steel to the tempering embrittlement, with the change of fracture micromechanisms involved in the failure process, when exposed to the environment of synthetic sea water under cathodic protection of -1100mVECS and to dynamic conditions of loading, where a reduction in the order of 60% and 30% of the fracture toughness value of the material was observed, respectively.

This thesis investigates the quantity Crack Tip Opening Displacement (CTOD) as a means to assess fracture toughness when measured in the Single Edge Notched Bend (SENB) specimen setup. A particular objective is to assess the effectiveness of the test when used for high strain-hardening materials (e.g. stainless steels). This has been an increasing concern as the current available methods were generally designed for lower strain hardening structural steel. Experimental work on CTOD tests included silicone casting of the crack, and constant displacement tests were also performed. The silicone castings enable physical measurement of the crack under an optical microscope. Results from a series of Finite Element (FE) models were validated from the experiments. δ5 surface measurements were obtained using Digital Image Correlation (DIC) as a courtesy of TWI, which were compared to surface CTOD measurements from the silicone castings. In addition to the experiments and Finite Element modelling, archived test data from TWI was processed, showing analytical differences between current Standard CTOD equations. CTOD calculations from BS 7448, ISO 12135, ASTM E1820 and WES 1108 were compared to the experimental and FE modelling results. For high strain hardening material, CTOD predicted by Standard equations (apart from those in BS 7448 and single point CTOD from ISO 12135) were lower than the values determined from silicone measurements and modelling. This potentially leads to over conservative values to be used in Engineering Critical Assessments (ECA) or material approval. Based on a series of different strain hardening property models, a relationship between strain hardening and the specimen rotational factor, rp was established. An improved equation for the calculation of CTOD is proposed, which gave good estimation of the experimental and Finite Element modelling results. The improved equation will be proposed for future amendments of the ISO 12135 standard. The results of this research enable the accurate fracture characterisation of a range of engineering alloys, with both low and high strain hardening behaviour in both the brittle and ductile fracture regime.

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Agradecemos a compreensão. on 2017-03-22T13:50:06Z (GMT) / Submitted by MARCELO MAJEWSKI null (marcelomajewski@bol.com.br) on 2017-03-23T01:46:44Z No. of bitstreams: 1 Marcelo [v13-03-2017vFINAL].pdf: 3845690 bytes, checksum: c51d5240a6bf0ae87ee09592959712cc (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-03-23T16:39:23Z (GMT) No. of bitstreams: 1 majewski_m_me_guara.pdf: 3845690 bytes, checksum: c51d5240a6bf0ae87ee09592959712cc (MD5) / Made available in DSpace on 2017-03-23T16:39:23Z (GMT). No. of bitstreams: 1 majewski_m_me_guara.pdf: 3845690 bytes, checksum: c51d5240a6bf0ae87ee09592959712cc (MD5) Previous issue date: 2017-02-06 / O aumento do uso de compósitos estruturais tem levado a uma preocupação constante com a confiabilidade destes materiais. Em particular, o processo de cura das resinas na fabricação é citado como um dos problemas mais significativos no processamento de compósitos estruturais. Assim, para que essa classe de materiais possa ser economicamente viável e atender às exigências dos padrões de qualidade do setor aeronáutico, tecnologias de processamento automatizado e novas formas de matéria-prima estão sendo desenvolvidas e implantadas na fabricação. Desta forma, o objetivo da presente pesquisa foi estudar a influência das propriedades térmicas dos materiais de moldes, utilizados no processamento de compósitos via RTM, nas propriedades finais dos laminados. Foram processadas três placas de compósitos com reforço não dobrável (NCF-non-crimp fabric) biaxial [+45°/-45°] via RTM: em molde de aço 1020, laminado 1; e em liga de alumínio 5052-F, laminados 2 e 3. Para verificar a influência dos materiais dos moldes nas propriedades finais, foram analisadas a tenacidade à fratura interlaminar em modo I e investigação das superfícies de fratura pelo Microscópio Eletronico de Varredura (MEV). O comportamento térmico estudado via análise térmica dinâmico-mecânica (DMA), que avaliou as diferenças no grau de cura dos laminados 1, 2 e 3 com a análise da Tg. Nos processamentos, evidenciou-se que o molde de alumínio apresentou maior controle e estabilidade térmica, enquanto que o molde de aço apresentou maior estabilidade dimensional. Pelo modo I, observou-se maior energia de iniciação de trinca (GIc) para o laminado 1 em relação aos laminados 2 e 3. Nas imagens de fratura no MEV constatou-se a influência da fração volumétrica de fibras e a quantidade de fiber bridging. No laminado 1, observou-se mechas de fibra sobre a costura e fibras rompidas originadas do fiber bridging, que foram responsáveis pela energia adicional exigida na propagação da trinca (GI). No laminado 2 observou-se acúmulo de resina e menor quantidade de fiber bridging, consequentemente, valores intermediários de GI, já no laminado 3 notou-se a ausência de fiber bridging, o que proporcionou a propagação da trinca no domínio da matriz, apresentando o menor valor GI entre os laminados. Nos dois últimos laminados a diminuição de GIc foi atribuida ao grau de cura da resina. Na qual observou-se as transições vítreas (Tg) próximas entre os laminados 1 e 3, e para o laminado 2 a Tg foi inferior, o que demonstrou efetiva correlação entre as características térmicas dos moldes com as propriedades físicas e mecânicas finais dos laminados compósitos obtidos via RTM. / The increase use of structural composites has led to a constant concern on the reliability of these materials. In particular, curing process of resins during manufacturing are cited as one of the most significant problems in the structural composites. Therefore, in order to this class of materials can be economically viable and meet the requirements of quality in the aeronautic industry standards, automated processing technologies and new materials have been developed and implemented in manufacturing sector. Thus, this research aimed to investigate the influence of thermal properties of the mold, which was used in the processing of composites via RTM, on the final properties of the laminates. Three composite plates comprised with NCF (non-crimp fabric) reinforcement, which has biaxial [+45°/-45°] configuration, and epoxy matrix. Two molds were employed for this investigation: steel 1020, for laminate 1, and aluminum alloy 5052-F, for laminates 2 and 3, all laminates with the same fiber stacking sequence. The influence of the materials of the molds in the final properties were verified with interlaminar fracture toughness in mode I (GIc), and their images of the fractured surfaces investigated by Scanning Electron Microscope (SEM). The thermal analysis conducted with Dynamic Mechanical Thermal Analysis (DMA), which evaluated the differences in the degree of cure of laminate 1, 2 and 3 by vitreous temperature transitions (Tg). It was evidenced that the aluminium mold showed better thermal conductivity and temperature stability, while the steel mold showed higher dimensional stability. Mode I showed higher energy crack initiation (GIc) for laminate 1 than for laminates 2 and 3. In the SEM images, it was verified a change in fiber volume fraction and the amount of fiber bridging. Laminate 1 showed fiber tows on the stitch regions and ruptured fibers originated from the fiber bridging, which were responsible for the additional energy of propagation (GI). Laminate 2 showed resin accumulation and less loose fibers, and consequently, intermediate values of GI, Laminate 3 no fiber bridging occured, which showed the propagation of the crack in the matrix domain, presenting the lowest GI value between the laminates. In laminates 2 and 3, the decrease in GIc can be attributed to the degree of cure, in which correlated to the glass transitions (Tg) results. Overall, the tests demonstrated a good correlation between the thermal characteristics of the molds with the final physical and mechanical properties of the laminates obtained via RTM.

O novo paradigma de se preservar o meio ambiente e de se utilizar produtos naturais vem contribuindo para um maior interesse na utilização de materiais derivados da biomassa. Neste sentido, os compósitos poliméricos com fibras vegetais surgem como uma boa alternativa no campo dos materiais para aplicações de engenharia. Os principais objetivos deste trabalho foram o processamento e a caracterização do compósito formado por uma resina poliuretano derivada do óleo de mamona e fibras de sisal e coco. O processamento foi realizado utilizando-se a técnica de moldagem por compressão. As fibras foram utilizadas em diferentes formas como fibras curtas, fibras longas, tecido e fios contínuos. A caracterização foi realizada através dos seguintes ensaios: tração, flexão, impacto, tenacidade à fratura, absorção d’água e DMTA. Foi também avaliado o efeito do tratamento com hidróxido de sódio (10%), nas fibras de sisal e coco, nas análises realizadas. O resultados mostraram que o desempenho dos compósitos com fibras de coco foi inferior aos compósitos com fibras de sisal, e mesmo ao poliuretano. Nos ensaios de tração e flexão, as fibras longas de sisal apresentaram o melhor efeito de reforçamento, seguido dos fios contínuos, fibras curtas e tecido. Nos ensaios de impacto e tenacidade à fratura, o melhor desempenho foi dos compósitos com tecido de sisal. O efeito do tratamento alcalino variou em função do tipo de ensaio e da geometria do reforço. Nos ensaios de tração e flexão, o seu efeito foi positivo para os compósitos com fibras longas e curtas, e negativo para os compósitos com tecido e fios, devido à deterioração da estrutura dos fios. Nos ensaios de tenacidade e impacto foi prejudicial, pois ao melhorar a aderência na interface, reduziu os principais mecanismos de absorção de energia, que são, a extração de fibras e o descolamento na interface. Com relação às medidas de absorção d’água, foi observado aumento no nível de absorção dos compósitos com o aumento da fração volumétrica de fibras. O máximo percentual de absorção foi de 17%, para os compósitos com fibras curtas de coco não tratadas. Este percentual diminuiu com o tratamento alcalino das fibras. Na análise térmica dinâmico mecânica, de uma forma geral, os compósitos mostraram acréscimo do módulo de armazenamento e decréscimo do amortecimento e da temperatura de transição vítrea, Tg, em relação ao poliuretano. Este comportamento foi proporcional ao aumento da fração volumétrica de fibras. / The new paradigm in preserving the environment and the use of natural products has contributed to increase the interest in the development and use of derived biomass materials. In this sense, the polymeric composites with natural fibers appear to be a good alternative for engineering applications. The main targets of this work were the processing and characterization of composites obtained by a polyurethane resin derived from castor oil and sisal and coir fibers. The compression moulding technique was used to process the composite. The fibers were employed in different forms such as: short fibers, long fibers, biaxial weave and continuos yarns. Tension, bend, impact, fracture toughness, water absorption and DMTA tests were used to characterize the composites. The sodium hidroxide (10%) treatment effect on the sisal and coir fibers was also evaluated. The results showed, in general, that the coir fibers composites performance were inferior to the sisal fibers composites, and even to the polyurethane matrix. Under tension and bending conditions, the long sisal fibers presented the best reinforcement effect, followed by the continuous yarns, short fibers, and the biaxial weave. Under impact and fracture toughness tests, the best performance was enhanced by sisal weave composites. The alkaline treatment effect varied in accordance with test type and reinforcement geometry. In tension and bending tests, its effect was positive for composites with short and long fibers and negative for composites with weave and yarns. This late was due to deterioration of the yarn structure. In the impact and toughness tests, the alkaline treatment effect was harmful, because when adherence is improved at the interface, the main energy absorption mechanisms are reduced, that mean, the fibers are pulled out and interface is debonded. Water absorption measurements showed an increase in the absorption level for the composites with higher volumetric fraction of fibers. The maximum water absorption was 17% for composites with non-treated coir short fibers. This percentage decreased for composites with treated fibers. In the dynamic mechanical thermal analysis (DMTA) the composites showed an increased storage modulus and a decreased glass transition temperature, Tg, when compared to polyurethane matrix. This behaviour was proportional to the increase of the fibers volumetric fraction.

Nas últimas décadas a soldagem em estado sólido vem demonstrando ser uma ótima alternativa frente aos métodos convencionais de união mais utilizados na indústria, dos quais a grande maioria consiste na soldagem por fusão dos materiais. O presente trabalho consiste na utilização do processo denominado como soldagem por fricção com pino consumível (Friction Hydro Pillar Processing – FHPP). Este trabalho visou avaliar a aplicação do processo FHPP em um aço utilizado para a fabricação de componentes de amarras de uso offshore, para esses aços o surgimento de defeitos durante operação ou fabricação trazem elevados custos operacionais, o reparo por soldagem a arco é não recomendado por normas técnicas devido às propriedades destes materiais e as condições de operação dos componentes produzidos com os mesmos. Esta avaliação se deu através da análise dos melhores parâmetros de processo (força axial, velocidade de rotação, consumo do pino e geometria de pinos e furos usinados) visando juntas soldadas livres de defeitos, avaliadas através de análises macrográficas, análises micrográficas e perfis de microdureza que por sua vez foram realizados visando a melhor caracterização das regiões que compõem a junta soldada Por fim, para a avaliação da tenacidade das juntas soldadas, ensaios de impacto Charpy e tenacidade à fratura (CTOD), seguidos de análises fractográficas em lupa e MEV (microscópio eletrônico de varredura), foram realizados com base em recomendações normativas visando uma avaliação precisa da tenacidade da região de união dos materiais soldados. As juntas soldadas apresentaram valores de CTOD de aproximadamente 40% dos valores obtidos em corpos de prova extraídos do material base. O desempenho das juntas soldadas nos ensaios de tenacidade foi claramente prejudicado pela presença de inclusões, observadas ainda no material base, que acabaram por concentrar-se nas interfaces de união das soldas devido às características do processo FHPP. / In the last few years the solid state welding has been a great alternative compared to the most common processes used in industry, which usually consists in fusion of the employed materials. The present study wants to evaluate the application of Friction Hydro-Pillar Processing (FHPP). This work aims to analyze the application of FHPP in steel used to manufacturing offshore mooring components where the incidence of defects during the operation and manufacturing result in elevated operational costs. In addition the repair of these components is not recommended by technical stand arts duo to properties of materials and operational conditions of components. The analyses was carried out by the optimization of process parameters (axial force, rotational speed, rod burn off, geometry of rod and machined hole) aiming, in the first step, free defects and sufficient heat input welded joints through analyses of macrographs. A subsequently detailed analysis of micrographs and micro hardness profile was made aiming a better characterization of all welding regions. Finally, Charpy impact tests and Crack Tip Opening Displacement (CTOD) tests were carried out, to toughness evaluation of welding joints Followed by fractography in scanning electron microscopy (SEM) was made based in recommended technical standards aiming more accurate about the toughness in bonding line regions of welded joints. The welded joints presented a CTOD tests result that where about 40% of the values obtained for the base material. The specimen performance in toughness tests was clearly adversely affected by the presence of inclusions in the bonding lines. Observed in material base during the first analyses, these inclusions have been found in large quantity on bonding lines of welds because a characteristic of FHPP to concentrate it in this region.

[pt] O estudo da mecânica da fratura aplicada às rochas vem se desenvolvendo desde os anos 60. Seu principal parâmetro, a tenacidade à fratura, quantifica a capacidade que a rocha possui para absorver energia até atingir a ruptura. Seu conhecimento é muito importante em diversas áreas da engenharia de rochas, como análise de estabilidade de taludes rochosos, processos de desmonte de rochas, escavações na mineração, fraturamento hidráulico, mecânica de terremotos, dentre outros. O presente estudo apresenta e analisa a influência do grau de alteração na tenacidade à fratura, no modo I de propagação, através de ensaio CCNDB (corpo de prova em forma de disco brasileiro com entalhe em chevron), de rochas gnáissicas da cidade do Rio de Janeiro. Amostras de diferentes graus de alteração foram caracterizadas quanto às suas propriedades mineralógicas, físicas (porosidade e peso específico) e mecânicas (resistência à compressão puntiforme, resistência à compressão uniaxial e resistência à tração). Nos resultados obtidos, são discutidas e realizadas correlações da tenacidade com as propriedades analisadas. Foi possível verificar que o grau de alteração é diretamente proporcional à porosidade e inversamente proporcional às resistências (compressão uniaxial e tração). Sendo assim, a rocha alterada apresenta maior porosidade e menor resistência, quando comparada com rochas menos alteradas (sãs e medianamente alteradas). A tenacidade à fratura para rochas medianamente alteradas é 45,9 por cento menor do que para rochas sãs, e 86,7 por cento menor para rochas alteradas. Assim sendo, o grau de alteração das rochas influencia, de maneira significativa, todas as propriedades analisadas. / [en] The study of fracture mechanics applied to rocks has been developed since 1960. The main parameter, fracture toughness, quantifies the rock ability to absorb energy until it ruptures. This knowledge is very important in several areas of rock engineering, such as stability analysis of rocky slopes, rock clearing processes, mining excavations, hydraulic fracturing, earthquake mechanic, among others. The study presents and analyzes the influence of the weathering class in the mode I fracture toughness of gneiss rocks in the city of Rio de Janeiro, using Cracked Chevron Noched Brazilian Disc (CCNDB). Samples of different classes were characterized for their mineralogical, physical (porosity and dry specific weight) and mechanical properties (point load strength, uniaxial compressive strength and tensile strength). The obtained results allowed correlations to be made between toughness and the other analyzed properties. By doing this, it was possible to verify that the weathering class of a rock is directly proportional to the porosity and inversely proportional to the strengths (uniaxial compressive and tensile). Thus, the highly weathered rock presents higher porosity and lower strength when compared to less weathered rocks (sound and moderated). The fracture toughness for moderately weathered rocks is 45,9 percent lower than sound rocks, and 86,7 percent smaller for highly weathered rocks. Therefore, the class of weathering rocks influences all the analyzed properties in a significant way.

No description available.

Lithium ion batteries (LIBs) have gained increasing popularity due to their high potential, low self-discharge, zero priming and minimal memory effect. However, the emergence of electrical vehicles and hybrid electrical vehicles in the automobile industry, where LIBs are predominantly in use, instilled a need to improve LIB batteries by experimenting with new materials. Graphite, the commonly used anode material for LIBs suffers from low theoretical capacity (372 mA h g-1) and torpid rate performance. Germanium (Ge) seems to be a promising substitute of carbon due to its high theoretical capacity, high Li+ diffusivity and electrical conductivity. However, Ge undergoes large volumetric change (±370%). This causes deboning of the thin film Ge electrode from the substrate current collector, causing a rapid decrease in the electrolytic performance. The process of ion beam mixing claims to have overcome this problem. In our current study, the adhesion strength of Ge thin film over Nickel (Ni) substrate (with and without ion beam mixing) is being measured using nanoindentation and the superlayer indentation test. Nanoindentation is one of the popular techniques to measure the mechanical properties and adhesion of thin film coatings. In this technique, a very small indenter of a desired geometry indents the film/substrate pair and the work of adhesion is calculated by knowing the plastic depth of indentation and the radius of indentation. Superlayer indentation is analogous to normal indentation but with a highly stressed superlayer on top to restrict the out-of-plane displacements, it reduces the plastic pile up around the indenter tip. The results from our study strongly suggest the possibility of dramatically increasing the adhesion strength by ion bombardment, which can be achieved by atomic level intermixing of the film/substrate pair. These, in turn, suggest that Ge could be an effective successor to graphite in the near future.

Afin d'examiner les effets de la cristallisation sur certaines propriétés mécaniques, l'évolution du module de Young (E), du module de cisaillement (G) et du coefficient de Poisson, ainsi que la séquence des phases cristallines formées au cours d'un traitement thermique en deux étapes ont été accompagnées sur un verre baptisé 75-25, du système MgO-Al2O3-SiO2 (MAS), en utilisant TiO2 comme le principal agent de nucléation. L'évolution de la dureté et de la résistance à la rupture a aussi été examinée. La diffractométrie de Rayons X à haute température a révélé, après cristallisation, la présence de spinelle (MgO.Al2O3) rutile (TiO2), karooite (MgO.2TiO2), sillimanite (Al2O3.SiO2) et la saphirine (4MgO.5Al2O3.2SiO2). Les modules élastiques et de cisaillement des vitrocéramiques (VC) se sont montré environ 20% plus élevés que ceux du verre précurseur. Les valeurs de dureté obtenues sont proches de 10 GPa et KIC proche de 1,2 MPa.m1/2. Dans le but de fabriquer des VCs transparentes et incolores, de nouvelles formulations, dénommées ZT1B4, 75-25/ZT et 75-25/25TI, avec des teneurs en TiO2 réduites et des teneurs en ZrO2 plus élevées, ont été proposées et cristallisées. La formulation ZT1B4 a produit une VC transparente avec une dureté maximale de 8GPa et une ténacité à la fracture (TF) à peu près 40% plus élevée que celle du verre de base. Les formulations 75-25 ZT et 75-25/25Ti ont produit des VC transparentes avec des valeurs de dureté allant jusqu'à 9GPa et une ténacité à la fracture jusqu'à 35% plus élevée que celle du verre de base. Une série de verres ont été fondus en utilisant Ag métallique, au lieu de ZrO2 et TiO2, en tant qu'agent de nucléation. Les traitements thermiques appliqués ont produit des VCs non-homogènes, qui perdent la forme en raison des températures de cristallisation élevées. Ces nouveaux verres précurseurs ont donc été écartés. La transmittance dans la région de l'ultraviolet et visible a été mesurée dans les échantillons de verre et VCs de formulation 75-25, 75-25 / ZT et 75-25 / 25TI. La formulation 75-25 / ZT a présenté la plus haute transmittance soit à l'état vitreux ou en forme de vitrocéramique. En conclusion, parmi les nouvelles compositions, la formulation 75-25 / ZT est la plus adéquate pour une utilisation en tant que protection balistique, lorsque la transparence à la lumière visible est nécessaire. / In situ experiments were conducted on a glass dubbed 75-25, of the MgO-Al2O3-SiO2 (MAS) system, using TiO2 as the main nucleating agent, in order to examine the evolution of Young’s modulus (E), shear modulus (G) and Poisson's ratio, and the sequence of the crystalline phases formed during a double-stage heat treatment. The effects of crystallization on hardness and fracture toughness were also examined. High temperature X-ray diffraction experiments revealed the presence of spinel (MgO.Al2O3), rutile (TiO2), karooite (MgO.2TiO2), sillimanite (Al2O3.SiO2) and sapphirine (4MgO.5Al2O3.2SiO2) after crystallization. The elastic and shear moduli of the glass-ceramics (GC) were approximately 20% larger than those of the parent glass. Hardness values were close to 10 GPa and KIC close to 1.2 MPa.m1/2. Aiming to obtain transparent and colorless GC, new formulations, dubbed ZT1B4, 75-25/ZT and 75-25/25Ti, with lower titania content and higher zirconia content, were proposed and crystallized. Formulation ZT1B4 yielded a transparent GC with hardness of up to 8 GPa and an indentation fracture toughness (IFT) about 40% higher than that of the parent glass. Formulations 75-25/ZT and 75-25/25Ti yielded transparent GC with hardness values of up to 9 GPa and an IFT up to 35% higher than that of the parent glass. A series of glasses were also melted using metallic Ag as nucleating agent instead of ZrO2 and TiO2. The applied heat treatments generated non-homogeneous GC, which became warped due to the high crystallization temperatures. These new precursor glasses were therefore discarded. Transmittance in the ultraviolet to visible range was measured in the glass and GC samples of formulations 75-25, 75-25/ZT and 75-25/25Ti. Formulation 75-25/ZT presented the highest transmittance in both glass and GC states. It was concluded that among the new compositions, formulation 75-25/ZT is the most suitable one for use as ballistic protection when transparency to visible light is required.

There is a technological need for hard thin films with high elastic modulus. Silicon Carbide (SiC) fulfills such requirements with a variety of applications in high temperature and MEMS devices. A detailed study of SiC thin films mechanical properties was performed by means of nanoindentation. The report is on the comparative studies of the mechanical properties of epitaxially grown cubic (3C) single crystalline and polycrystalline SiC thin films on Si substrates. The thickness of both the Single and polycrystalline SiC samples were around 1-2 µm. Under indentation loads below 500 µ-Newton both films exhibit Elastic contact without plastic deformation. Based on the nanoindentation results polycrystalline SiC thin films have an elastic modulus and hardness of 422 plus or minus 16 GPa and 32.69 plus or minus 3.218 GPa respectively, while single crystalline SiC films elastic modulus and hardness of 410 plus or minus 3.18 Gpa and 30 plus or minus 2.8 Gpa respectively. Fracture toughness experiments were also carried out using the nanoindentation technique and values were measured to be 1.48 plus or minus 0.6 GPa for polycrystalline SiC and 1.58 plus or minus 0.5 GPa for single crystal SiC, respectively. These results show that both polycrystalline SiC thin films and single crystal SiC more or less have similar properties. Hence both single crystal and polycrystalline SiC thin films have the capability of becoming strong contenders for MEMS applications, as well as hard and protective coatings for cutting tools and coatings for MEMS devices.