Página 1 dos resultados de 672 itens digitais encontrados em 0.004 segundos

Diagnostic of Silicon Carbide Surge Arresters using Leakage Current Measurement

KANASHIRO, A. G.; ZANOTTI JR., M.; OBASE, P. F.; BACEGA, W. R.
Fonte: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC Publicador: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
707.05516%
Nowadays, the zinc oxide surge arresters (ZnO) are widely used in power systems, however, a large number of silicon carbide surge arresters (SiC) are still in service in the utilities. On the other hand, it is not possible to replace all SiC surge arresters in a short time period, being necessary to review the maintenance program taking into account the surge arresters that are more degraded. In this context, a research project was established between the University of Sao Paulo and the electrical utility CTEEP, aiming the investigation of its SiC surge arresters. This work shows that the leakage current measurement, a diagnostic method for the ZnO surge arresters, can provide useful information related to the condition of the SiC surge arresters. Analysis of the amplitude and distortion of the leakage current, also considering thermovision measurements, resulted in better evaluation of the SiC surge arresters.

Estudo da viabilidade de fabricação de dispositivos semicondutores baseados em filmes de carbeto de silício crescidos por PECVD.; Study of the viability of production of semiconductors devices based on silicon carbide films grown by PECVD.

Oliveira, Alessandro Ricardo de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 31/08/2006 PT
Relevância na Pesquisa
720.86875%
Neste trabalho é estudada a viabilidade de produção de dispositivos eletrônicos baseados em filmes semicondutores de carbeto de silício estequiométrico (a-Si0,5C0,5:H) obtidos por deposição química por vapor assistida por plasma, PECVD. A proposta do projeto envolve a realização de uma série de trabalhos que permitam avaliar as potencialidades do a-SiC:H para a fabricação de dispositivos semicondutores simples. Deste modo, desenvolvemos as principais etapas para a construção de dispositivos, as quais envolveram a dopagem elétrica por diferentes técnicas com a utilização de diferentes elementos dopantes, a corrosão seletiva por plasma e a obtenção um dielétrico apropriado e compatível com a tecnologia do SiC, bem como o desenvolvimento de processos de cristalização, que podem se mostrar fundamentais para melhorar as propriedades dos filmes de a-SiC:H. Com tais processos aprimorados, fabricamos estruturas MOSiC (metal-óxidocarbeto de silício) a partir do SiC cristalizado, utilizando como dielétrico de porta o SiO2 crescido por oxidação térmica (seca e úmida) dos próprios filmes de carbeto de silício cristalizados. Essas estruturas apresentaram o comportamento típico de um capacitor MOS, com regiões de acumulação...

Análise da viabilidade da substituição dos tubos de um trocador de calor casco e tubos de vidro por carbeto de silício; Analysis of the viability of change the glass tubes in a shell and tubes heat exchange for silicon carbide

Rosa, Ricardo Badek
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Trabalho de Conclusão de Curso Formato: application/pdf
POR
Relevância na Pesquisa
707.05516%
Uma empresa, do ramo petroquímico, situada em Triunfo - RS usa ácido sulfúrico em seus processos, que deve estar a uma concentração de 80%. Após passar pelo processo o ácido que não reage retorna em altas temperaturas e na concentração de 40%. Por este motivo existe uma área de reconcentração deste ácido para que ele possa retornar ao processo. Mas como ele chega a uma temperatura elevada do processo usam-se trocadores de calor casco e tubos para resfriar o ácido, para que ele possa então ser reconcentrado e armazenado. Poucos materiais resistem bem a este meio agressivo. Um deles é o vidro, do qual é fabricado o trocador de calor que existe e opera atualmente na planta. Outro material capaz de resistir à corrosão é o carbeto de silício. O presente trabalho mostra a análise térmica da substituição dos tubos de um trocador de calor casco e tubos de vidro por outro de carbeto de silício, com os resultados que seriam obtidos com esta mudança.; A petrochemical company, located in Triunfo – RS, uses sulfuric acid @ 80% in its process. At the end of this process the sulfuric acid returns in high temperature and @ 40%. For this reason there is a re-concentration area in order to reuse this acid again in its process. They use shell and tubes heat exchangers as a cooler of this acid...

Camadas antirrefletoras de carbono amorfo e carbeto de silício para células solares de silício cristalino; Antireflective coatings of amorphous carbon and silicon for crystalline silicon solar cells

Douglas Soares da Silva
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/03/2009 PT
Relevância na Pesquisa
618.39703%
Nesta tese estamos propondo o uso de carbono amorfo como um possível candidato para uso como camada antirrefletora em células solares de silício cristalino. O carbono amorfo pode ser preparado com alta banda proibida e tem propriedades importantes como alta dureza, baixo coeficiente de atrito, preparado à temperatura ambiente, etc. Além disso, o carbono amorfo é um material abundante na natureza e seu uso em eletrônica poderia reduzir o consumo de materiais tóxicos, contribuindo para reduzir danos ao meio ambiente. Foram exploradas as propriedades óticas dos filmes de carbono e carbono de silício produzidos por diferentes métodos de deposição (RF Glow Discharge, RF Sputtering e FCVA_Filtered Cathodic Vacuum Arc) visando a aplicação como camadas antirrefletoras em células solares. O estudo de propriedades óticas dos filmes, como a banda proibida, índice de refração, coeficiente de absorção e reflexão integrada foram determinantes para as conclusões deste trabalho. Para isto foram importantes a fabricação de células solares e o estudo dos principais parâmetros fotovoltaicos: eficiência, corrente de curto circuito, tensão de circuito aberto e fator de preenchimento. As células solares de silício monocristalino foram desenvolvidas a partir da técnica amplamente difundida e conhecida através da difusão térmica de dopantes de fósforo...

Silicon-incorporated diamond-like coatings for Si3N4 mechanical seals

Camargo Junior, S. S.; Gomes, J. R.; Carrapichano, J. M.; Silva, R. F.; Achete, C. A.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /11/2005 ENG
Relevância na Pesquisa
602.83402%
Amorphous silicon carbide (a-SiC) and silicon-incorporated diamond-like carbon films (DLC-Si) were evaluated as protective and friction reduction coatings onto Si3N4 rings. Unlubricated tribological tests were performed with a pin-on-disk apparatus against stainless steel pins with loads ranging from 3 N to 55 N and sliding velocities from 0.2 m/s to 1.0 m/s under ambient air and 50-60% relative humidity. At the lowest loads, a-SiC coatings present a considerable improvement with respect to the behavior of uncoated disks since the friction coefficient is reduced to about 0.2 and the system is able to run stably for thousands of meters. At higher loads, however, a-SiC coatings fail. DLC-Si coated rings, on the other hand, presented for loads up to 10 N a steady state friction coefficient below 0.1 and very low wear rates. The lowest steady-state mean friction coefficient value of only 0.055 was obtained with a sliding velocity of 0.5 m/s. For higher loads in the range of 20 N the friction coefficient drops to values around 0.1 but no steady state is reached. For the highest loads of over 50 N a catastrophic behavior is observed. Typically, wear rates below 5 x 10-6 mm3/N.m and 2 x 10-7 mm3/N.m were obtained for the ceramic rings and pins...

New catalysts based on silicon carbide support for improvements in the sulfur recovery. Silicon carbide as support for the selective H2S oxidation

Keller,Nicolas; Vieira,Ricardo; Nhut,Jean-Mario; Pham-Huu,Cuong; Ledoux,Marc J.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2005 EN
Relevância na Pesquisa
715.29016%
The NiS2 and Fe2O3 active phases supported on medium surface area beta-silicon carbide (SiC) showed high activity, selectivity and stability in the direct oxidation of H2S into elemental sulfur. The catalysts were tested under a large range of temperatures, from room temperature using Ni (trickle-bed reactor) to over-dewpoint temperatures using Fe (fixed bed reactor). For both cases, the formation on stream of a Ni and Fe oxysulfide high active phase was proposed by oxidation of NiS2 and sulfidation of Fe2O3, respectively. The absence of microporosity in the support contributed to the high selectivity into sulfur. At low temperatures (below 100 ºC), the high stability of beta-SiC supported catalysts towards the solid sulfur loading was explained by a specific mode of sulfur deposition, involving the role of water in the feed and the heterogeneous nature of the SiC surface, being partly hydrophilic and hydrophobic.

New catalysts based on silicon carbide support for improvements in the sulfur recovery: new silicon carbide nanotubes as catalyst support for the trickle-bed H2S oxidation

Keller,Nicolas; Vieira,Ricardo; Nhut,Jean-Mario; Pham-Huu,Cuong; Ledoux,Marc J.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2005 EN
Relevância na Pesquisa
715.29016%
Silicon carbide nanotubes were prepared via a gas-solid reaction between SiO vapor and carbon nanotubes. The NiS2 active phase on this support displayed both a high catalytic activity and high solid sulfur storage capacity in the trickle-bed selective oxidation of H2S into elemental sulfur as compared to the grain-based SiC catalyst. The hypothesis of a confinement effect inside the SiC nanotubes has been put forward to explain the catalytic results. An artificial increase in the H2S partial pressure inside the tubes when compared to the H2S partial pressure outside the tubes would lead to an increase in the oxidation rate, due to the first order reaction rate toward H2S. The SiC nanotube supported catalyst displayed very high resistance to the sulfur loading, due to a peculiar mode of sulfur evacuation by condensed steam which allows the continuous cleaning of the active site. The high solid sulfur storage capacity was due to a much larger void volume between each SiC nanotube available for the sulfur storage, than the void volume of SiC support with a grain size morphology.

Determination of Boron in Silicon Carbide by ICP-OES and ICP-MS after Sample Preparation using Pyrohydrolysis

Muller,Cristiano C.; Nunes,Thieli S.; Muller,Aline L. H.; Dressler,Valderi L.; Flores,Erico M. M.; Muller,Edson I.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2015 EN
Relevância na Pesquisa
707.05516%
Pyrohydrolysis was used for sample preparation of silicon carbide (SiC) and subsequent determination of B using inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Important parameters for pyrohydrolysis method as temperature, air and water flow rates, reaction time and use of V2O5 were evaluated. In addition, a study of W spectral interference on B emission lines was evaluated for ICP-OES determination. Accuracy was evaluated using certified reference material (CRM BAM S003) and bias value lower than 1% between the certified and determined value was achieved. Limit of detection (LOD) of 0.010 μg g−1 was obtained using pyrohydrolysis and ICP-MS. Pyrohydrolysis is a very simple sample preparation method that allowed the use of deionized water as absorbing solution for B determination in SiC.

Review article: silicon carbide. Structure, properties and processing

Izhevskyi,V. A.; Genova,L. A.; Bressiani,J. C.; Bressiani,A. H. A.
Fonte: Associação Brasileira de Cerâmica Publicador: Associação Brasileira de Cerâmica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2000 EN
Relevância na Pesquisa
727.944%
In view of considerable interest in the development of liquid phase sintered structural and high-temperature ceramics on the base of silicon carbide, a comprehensive review of the data on structure, properties and the known methods of processing of silicon carbide seems timely. The most striking feature of silicon carbide is its polytypism, i.e. formation of a great number of different structural modifications without any change in composition. Although this feature of silicon carbide was extensively studied, no systematic up to date analysis was done. However, polytypism and the tendency of the polytypes to undergo structural transformations at working temperatures may lead to uncontrollable modification of the materials properties, and therefore needs to be fully understood. Furthermore, the recently developed liquid phase sintering technique for silicon carbide densification is of an undoubtful interest and the overview of the results achieved until present time may provide some guidelines for the ceramists.

Liquid phase sintering of silicon carbide with AlN/Y2O3, Al2O3/Y2O3 and SiO2/Y2O3 additions

Strecker,Kurt; Ribeiro,Sebastião; Camargo,Daniela; Silva,Rui; Vieira,Joaquim; Oliveira,Filipe
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/1999 EN
Relevância na Pesquisa
707.05516%
In this work, the influence of the additive system on the liquid phase sintering of silicon carbide has been investigated. The additives employed were mixtures of AlN/Y2O3, Al2O3/Y2O3 and SiO2/Y2O3. The total additive content was fixed at 20 vol.-%, maintaining the Y2O3 content in each additive system at 35 vol.-%. Cold isostatically pressed samples were sintered at 1900, 2000 and 2100 °C under Ar atmosphere during 30 min. The most promising results have been obtained by samples with AlN/Y2O3 additions sintered at 2000 °C, exhibiting the smallest weight loss of about 6% and the highest flexural strengths of about 433 MPa. Samples with Al2O3/Y2O3 and SiO2/Y2O3 additions exhibited high weight loss, because of reactions of Al2O3 and SiO2 with the SiC matrix, forming gaseous species such as Al2O, SiO and CO, resulting in depletion of the liquid phase, and, consequently, in inferior final densities and mechanical properties. Concerning the SiO2/Y2O3 additive system, the reactions seem to be completed already at temperatures below 1900 °C, turning this additive mixture unsuitable. The microstructural analysis indicated only the presence of the b-SiC phase for all samples; no phase transformation of the b-SiC into a-SiC has been observed.

Densification studies of silicon carbide-based ceramics with yttria, silica and alumina as sintering additives

Marchi,J.; Bressiani,J.C.; Bressiani,A.H.A.
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2001 EN
Relevância na Pesquisa
715.29016%
Silicon carbide has been extensively used in structural applications, especially at high temperatures. In this work, Y2O3, Al2O3 and SiO2 were added to beta-SiC in order to obtain highly dense ceramics. Sintering was conducted in a dilatometer and in a graphite resistance furnace and the densification behaviour was studied. Sintered samples were characterised by density measurements, the crystalline phases were identified by X-ray diffraction. Microstructural observation of polished and polished/etched samples was carried out with help of scanning electron microscopy. Silicon carbide ceramics with more than 90% of the theoretical density were obtained by pressureless sintering if a suitable proportion of the additives is used.

Dilatometric studies of (SiO2-RE2O3-Al2O3) silicon carbide ceramics

Marchi,Juliana; Bressiani,José Carlos; Bressiani,Ana Helena de Almeida
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2005 EN
Relevância na Pesquisa
717.6542%
Silicon carbide is an important structural ceramic and finds applications as abrasives, as a refractory and in automotive engine components. This material can attain high densities during liquid phase sintering if suitable additives are used. Silicon carbides containing silica, alumina and rare earth oxides have suitable characteristics to promote liquid phase sintering. In this paper, the sintering behavior of silicon carbide ceramics with additives based on the (SiO2-RE2O3-Al2O3) system (RE = Y, Dy) has been studied. Samples with different compositions and containing 90 vol.% SiC were sintered in a dilatometer at 1950 °C/1h and in a graphite resistance furnace from 1500 °C/1h up to 1950 °C/1h. The shrinkage behavior as a function of rare earth oxide used and additive composition was also studied. The sintered materials were characterized by density and weight loss measurements. The crystalline phases were identified by X-ray diffraction analysis. The sintering kinetics of these materials can be related to the formation of secondary crystalline phases.

Process development of silicon-silicon carbide hybrid structures for micro-engines (January 2002)

Choi, D.; Shinavski, R.J.; Spearing, S. Mark
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Tipo: Artigo de Revista Científica Formato: 1354372 bytes; application/pdf
EN_US
Relevância na Pesquisa
726.9145%
MEMS-based gas turbine engines are currently under development at MIT for use as a button-sized portable power generator or micro-aircraft propulsion sources. Power densities expected for the micro-engines require very high rotor peripheral speeds of 300-600m/s and high combustion gas temperatures of 1300-1700K. These harsh requirements for the engine operation induce very high stress levels in the engine structure, and thus call for qualified refractory materials with high strength. Silicon carbide (SiC) has been chosen as the most promising material for use due to its high strength and chemical inertness at elevated temperatures. However, the state-of-the art microfabrication techniques for single-crystal SiC are not yet mature enough to achieve the required level of high precision of micro-engine components. To circumvent this limitation and to take advantage of the well-established precise silicon microfabrication technologies, silicon-silicon carbide hybrid turbine structures are being developed using chemical vapor deposition (CVD) of thick SiC (up to ~70µm) on silicon wafers and wafer bonding processes. Residual stress control of thick SiC layers is of critical importance to all the silicon-silicon carbide hybrid structure fabrication steps since a high level of residual stresses causes wafer cracking during the planarization...

Silver transport in CVD silicon carbide; Silver transport in chemical vapor deposition silicon carbide

MacLean, Heather J. (Heather Jean), 1974-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 138 p.; 8028475 bytes; 8028282 bytes; application/pdf; application/pdf
ENG
Relevância na Pesquisa
527.944%
Ion implantation and diffusion couple experiments were used to study silver transport through and release from CVD silicon carbide. Results of these experiments show that silver does not migrate via classical diffusion in silicon carbide. Silver release is, however, likely dominated by vapor transport through cracks in SiC coatings. The results of silver ion implantation in silicon carbide and subsequent annealing at 1500ʻC place an upper limit on the silver diffusion coefficient in SiC of 5x10-21 m2/s, a value which is roughly 6 orders of magnitude less than the previous values reported in the literature. Silver diffusion should have been easily observable, but was not detected in SiC plates after heat treatments at 1500ʻC for times ranging between 200 h and 500 h. A detailed investigation of the silver morphology within the SiC both before and after heating showed that silver was immobilized at SiC grain boundaries and did not diffuse along them as expected. Novel spherical diffusion couples were fabricated containing silver inside shells of either graphite or SiC which were coated with CVD SiC. Mass measurements clearly revealed silver release from the diffusion couples after heating, but no silver was detected during concentration profile measurements in the SiC. Leak testing results...

Efeito da adição de carboneto de silício em pó na geração de microtrincas e na topografia da superfície na usinada por descargas elétricas do aço-rápido ABNT M2; Effect of the addition of silicon carbide powder on the microcrack generation and on the surface topography in electrical discharge machining of ABNT M2 high speed steel,

Rodrigues, Jean Robert Pereira
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Dissertação
POR
Relevância na Pesquisa
707.05516%
Este trabalho investiga a topografia de superfície e a geração de microtrincas superficiais e subsuperfíciais em peças de Aço Rápido ABNT M2, usinadas por descargas elétricas, com e sem adição de carboneto de silício em pó a três fluídos dielétricos comerciais A, B, C (identificados no trabalho), utilizando-se um eletrodo-ferramenta de cobre eletrolítico em regime de desbaste. A avaliação das microtrincas contou com a utilização dos microscópios eletrônico de varredura e óptico, e se deu através de dois parâmetros: a densidade de microtrincas e o valor médio de seus comprimentos. Para a avaliação da textura superficial, adotou-se o parâmetro Ra como parâmetro para análise do acabamento superficial, enquanto que a topografia de superfície foi avaliada através do microscópio eletrônico de varredura. De forma geral pode-se afirmar que as amostras usinadas com a adição de pós de SiC apresentaram significativas melhorias no acabamento superficial, quando comparadas com as usinadas com EDM convencional. Sob o ponto de vista das microtrincas, observou-se que a adição de pós não teve muita influência sobre o comprimento médio, no entanto, a ação destes foi mais positiva sobre a densidade. Tais resultados...

Polytypism and Silicon carbide : a solid state nuclear magnetic resonance study

Winsborrow, Beatrice G.
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
ENG
Relevância na Pesquisa
732.3652%
A survey of predominantly industrial silicon carbide has been carried out using Magic Angle Spinning nuclear magnetic resonance (MAS nmr); a solid state technique. Three silicon carbide polytypes were studied; 3C, 6H, and 15R. The 13C and 29 Si MAS nmr spectra of the bulk SiC sample was identified on the basis of silicon (carbon) site type in the d iff ere n t pol Y t Y pes • Out to 5.00 A fro mac en t r a lsi 1 i con (0 r carbon) atom four types of sites were characterized using symmetry based calculations. This method of polytype analysis was also considered, in the prelminary stages, for applications with other polytypic material; CdBr 2 , CdI 2 , and PbI 2 " In an attempt to understand the minor components of silicon carbide, such as its surface, some samples were hydrofluoric acid washed and heated to extreme temperatures. Basically, an HF removable species which absorbs at -110 ppm (Si0 2 ) in the 29 Si MAS nmr spectrum is found in silicon carbide after heating. Other unidentified peaks observed at short recycle delays in some 29 Si MAS nmr spectra are considered to be impurities that may be within the lattice. These components comprise less than 5% of the observable silicon. A Tl study was carried out for 29 Si nuclei in a 3C ii polytype sample...

Oxidation and wet wear of silicon carbide; Oxidationsverhalten und nass-tribologisches Verhalten von Siliciumcarbid

Presser, Volker
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
720.86875%
Siliziumkarbid (SiC) ist sowohl die wohl bedeutendste Nichtoxidkeramik aber auch als Halbleiter ein vielversprechendes Material. Gaskorrosion in Gegenwart von Sauerstoff führt dabei als einzige feste Phase zu Bildung von SiO2 (passive Oxidation). Hierbei spielen jedoch viele Einflussfaktoren eine wichtige Rolle, wie zum Beispiel Porosität, Sinteradditive, Verunreinigungen, die kristallographische Orientierung, vorhergehende Oberflächenbehandlung und die chemische Zusammensetzung der oxidierenden Atmosphäre. Als Folge von Kristallisation verändert die zunächst glasartige SiO2-Schicht ihre Struktur und es kommt zur Ausbildung von runden Kristallisationszentren (Radialite). Diese Bereiche zeigen eine geringere Oxidationsrate, was auf langsamere Gasdiffusion zurückzuführen ist. Verunreinigungen, wie sie Beispielsweise in der Ofenatmosphäre vorkommen können, akkumulieren sich auf der Oberfläche der SiO2-Schicht und es kommt zu einer schmelzkatalysierten Rekristallisation als zweiter morphologischer Umwandlung der Oxidschicht. Schließlich bilden sich kleine kristalline Kugeln (Globulite). Das dazwischen befindliche Porenvolumen führt zu erhöhten Oxidationsraten. Die Gesamtkinetik der Oxidation ist somit potentiell komplex. Dennoch kann für die meisten SiC Materialvarianten ein allgemeines linear-parabolisch Zeitgesetz für den gesamten Oxidationsverlauf gefunden werden. Die ausgeprägte Anisotropie von SiC führt dazu...

A DFT Investigation of the Interactions of Pd, Ag, Sn and Cs with silicon carbide

RABONE JEREMY; KOVACS ATTILA
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Articles in periodicals and books Formato: Printed
ENG
Relevância na Pesquisa
529.7665%
With a view to understanding the diffusion of radionuclides through the silicon carbide layers in Tristructural Isotropic (TRISO) coated fuel particles, density functional theory (DFT) calculations are applied to palladium, silver, tin and caesium with silicon carbide. The silicon carbide molecule (Si2C2), crystalline cubic silicon carbide (β-SiC) and the (120) Σ5 grain boundary of β-SiC are investigated to elucidate the differences in the interactions of silicon carbide with these elements. The calculations show that the electronic interactions have a significant effect on the way these elements interact with the silicon and carbon atoms of silicon carbide. The lowest energy structure of the AgSi2C2 complex is unique to silver, although for all these elements low energy structures are formed where the metal atom lies to one side of a C-Si bond. By comparing the incorporation energies in the solid phases, it is possible to group these elements by similarities in the patterns of incorporation energies. Silver and palladium form a group with carbon, tin is grouped with silicon and caesium is on its own.; JRC.E.3-Materials research

Synthesis of Silicon Carbide Nanowires on Carbon Nanotube Template

Li, Chi; Fitz Gerald, John; Zou, Jin; Chen, Ying
Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc) Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)
Tipo: Conference paper
Relevância na Pesquisa
720.6526%
Single crystalline silicon carbide nanowires (SiCNWs) growing along 〈111〉 direction were synthesized on a carbon nanotube (CNT) template. A powder mixture of silicon monoxide (SiO) and iron (II) phthalocyanine, FeC32N8H16, (FePc) was mechanically ball

Ciliary motion in PECVD silicon carbide and silicon oxynitride microstructures

Rehder,G; Carreño,M.N.P
Fonte: Sociedad Mexicana de Física Publicador: Sociedad Mexicana de Física
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2006 EN
Relevância na Pesquisa
712.9091%
The development of arrays of amorphous hydrogenated silicon carbide (a-SiC:H) and silicon oxynitride (SiOxNy) based microstructures that produce ciliary motion is presented. The arrays are fabricated by bulk micromachining of c-Si substrates and they are completely based on materials obtained by a low temperature PECVD (plasma enhanced chemical vapor deposition) technique. Chromium metal is sandwiched between these two materials and it is used as a contact metal and heating element. The ciliary motion is obtained by applying an external synchronized electrical voltage to the cantilevers, which move due to thermal expansion caused by the Joule Effect.