alpha-SiAlON-SiC composites obtained by gas-pressure sintering and hot-pressing
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Data
2007-07-06
Orientador
Coorientador
Pós-graduação
Curso de graduação
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Título de Volume
Editor
Elsevier B.V.
Tipo
Artigo
Direito de acesso
Acesso restrito
Resumo
The objective of this work was the obtaining in situ of alpha-SiAlON-SiC composite, using an alternative rare-earth oxide mixture, RE2O3, as sintering additive, by two different sintering processes. As sintering additive, 20 vol.% of AlN-RE2O3 in a molar ratio of 90: 10 was mixed to the alpha-Si3N4 powder. In the Si3N4-AlN-RE2O3 powder mixture, 0, 10, 15 and 20wt.% of SiC were added. The powder batches were milled, dried and compacted by cold isostatic pressing. Two different sintering processes were used: gas-pressure sintering at 1950 degrees C for 1 h under 1.5 MPa of N-2 atmosphere, or uniaxial hot-pressing at 1750 degrees C, for 30 min under pressure of 20 MPa. The sintered samples were characterized by X-ray diffraction, scanning electron microscopy and mechanical properties. XRD patterns indicate only alpha-SiAlON (alpha') and beta-SiC as crystalline phases. It was observed that the SiC addition did not influence the alpha-SiAlON formation, although the growth of elongated alpha'-grains is substantially decreased. The hot-pressed composites presented better mechanical properties, exhibiting fracture toughness of 5 MPa m(1/2) and hardness around 21.5 GPa. (c) 2007 Elsevier B.V. All rights reserved.
Descrição
Palavras-chave
alfa-SiAlON-SiC composite, Mechanical properties, Microstructure, Sintering processes, Fracture toughness, Grain growth, Hot pressing, Rare earth additions, Scanning electron microscopy, Silicon carbide, Sintering, X ray diffraction, Cold isostatic pressing, Molar ratio, Uniaxial hot pressing, Composite materials
Idioma
Inglês
Como citar
Journal of Materials Processing Technology, v. 189, n. 1-3, p. 138-142, 2007.
