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Previous issue date: 2012-06-06 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Nickel alloys are frequently used in applications that require resistance at high temperatures associated with resistance to corrosion. Alloys of Ni-Si-C can be obtained by means of powder metallurgy in which powder mixtures are made of metallic nickel powders with additions of various alloying carriers for such were used in this study SiC, Si3N4 or Si metal with graphite. Carbonyl Ni powder with mean particle size of 11 mM were mixed with 3 wt% of SiC powders with an average particle size of 15, 30 and 50 μm and further samples were obtained containing 4 to 5% by mass of SiC with average particle size of 15 μm. Samples were also obtained by varying the carrier alloy, these being Si3N4 powder with graphite, with average particle size of 1.5 and 5 μm, respectively. As a metallic Si graphite with average particle size of 12.5 and 5 μm, respectively. The reference material used was nickel carbonyl sintered without adding carriers. Microstructural characterization of the alloys was made by optical microscopy and scanning electron microscopy with semi-quantitative chemical analysis. We determined the densities of the samples and measurement of microhardness. We studied the dissociation of carriers alloy after sintering at 1200 ? C for 60 minutes. Was evaluated also in the same sintering conditions, the influence of the variation of average particle size of the SiC carrier to the proportion of 3% by mass. Finally, we studied the influence of variation of the temperatures of sintering at 950, 1080 and 1200 ? C without landing and also with heights of 30, 60, 120 and 240 minutes for sintering where the temperature was 950 ?C. Dilatometry curves showed that the SiC sintered Ni favors more effectively than other carriers alloy analyzed. SiC with average particle size of 15 μm active sintering the alloy more effectively than other SiC used. However, with the chemical and morphological analyzes for all leagues, it was observed that there was dissociation of SiC and Si3N4, as well as diffusion of Si in Ni matrix and carbon cluster and dispersed in the matrix, which also occurred for the alloys with Si carriers and metallic graphite. So the league that was presented better results containing Si Ni with graphite metallic alloy as carriers, since this had dispersed graphite best in the league, reaching the microstructural model proposed, which is necessary for material characteristic of solid lubricant, so how we got the best results when the density and hardness of the alloy / Ligas de N?quel s?o freq?entemente utilizadas em aplica??es que requerem resist?ncia mec?nica a elevadas temperaturas associada ? resist?ncia ? corros?o. Ligas de Ni-Si-C podem ser obtidas por meio de metalurgia do p? em que s?o realizadas misturas de p?s de n?quel met?lico com adi??es de p?s de diferentes portadores de liga, para tal foram utilizados neste trabalho SiC, Si3N4 ou Si met?lico com grafita. P?s de Ni carbonila com tamanho m?dio de part?culas de 11 μm foram misturados a 3% em massa de p?s de SiC com tamanho m?dio de part?culas de 15, 30 e 50 μm e foram obtidas ainda amostras contendo 4 e 5% em massa de SiC com tamanho m?dio de part?culas de 15 μm. Tamb?m foram obtidas amostras variando-se o portador de liga, sendo estes p?s de Si3N4 com grafita, com tamanho m?dio de part?culas de 1,5 e 5 μm, respectivamente. Assim como Si met?lico com grafita, com tamanho m?dio de part?culas de 12,5 e 5 μm, respectivamente. O material de refer?ncia adotado foi n?quel carbonila sinterizado sem adi??o de portadores. A caracteriza??o microestrutural das ligas foi feita por microscopia ?ptica e eletr?nica de varredura com an?lise qu?mica semi-quantitativa. Foram determinadas as densidades das amostras e obtidas medidas de microdureza Vickers. Foi estudada a dissocia??o dos portadores de liga ap?s sinteriza??o em 1200 ?C durante 60 minutos. Foi avaliada, ainda, para as mesmas condi??es de sinteriza??o, a influencia da varia??o do tamanho m?dio de part?culas do portador SiC, para a propor??o de 3% em massa. Por fim, foi estudo a influencia da varia??o das temperaturas de sinteriza??o em 950, 1080 e 1200 ?C sem patamar e, ainda, com patamares de 30, 60, 120 e 240 minutos para sinteriza??o cuja temperatura foi de 950 ?C. As curvas de dilatometria mostraram que o SiC favorece a sinteriza??o do Ni de forma mais eficaz que os demais portadores de liga analisados. O SiC com tamanho m?dio de part?culas de 15 μm ativa a sinteriza??o da liga de forma mais eficaz que os demais SiC utilizados. Por?m, com as an?lises qu?mica e morfol?gica para todas as ligas, foi poss?vel observar que houve dissocia??o do SiC e do Si3N4, assim como difus?o do Si na matriz de Ni e carbono aglomerado e disperso na matriz, o que tamb?m ocorreu para as ligas com portadores Si met?lico e grafita. Portanto, a liga que apresentou melhores resultados foi de Ni contendo Si met?lico com grafita como portadores de liga, j? que esta apresentou grafita melhor dispersa na liga, atingindo o modelo microestrutural proposto, do qual ? necess?rio para material com caracter?stica de lubrificante s?lido, assim como obteve os melhores resultados quando a densidade e dureza da liga
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/12758 |
| Date | 06 June 2012 |
| Creators | Nicodemo, Juliana Pivotto |
| Contributors | CPF:15724520800, http://lattes.cnpq.br/0022988322449627, Klein, Aloisio Nelmo, CPF:17131677000, http://lattes.cnpq.br/4087752487104746, Binder, Cristiano, CPF:02607912962, http://lattes.cnpq.br/0692818548181755, Peres, Maur?cio Mhirdaui, CPF:17536268890, http://lattes.cnpq.br/3068024292581677, Martinelli, Ant?nio Eduardo |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Ci?ncia e Engenharia de Materiais, UFRN, BR, Processamento de Materiais a partir do P?; Pol?meros e Comp?sitos; Processamento de Materiais a part |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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