Microstructure and properties tailoring of liquid-phase sintered SiC

Author(s)

Izhevskyi, V. A. ; Genova, L. A. ; Bressiani, A. H. A. ; Bressiani, J. C. ^[4]

• Document type: Journal article
• Source: International Journal of Refractory Metals and Hard Materials; v. 19, n. 4/6, p. 409-417, July 2001.
• Field of knowledge: Engineering - Materials and Metallurgical Engineering

Abstract

Silicon carbide (SiC) ceramics of the composition SiC-10 vol% (AlN-Y2O3) were liquid-phase sintered without application of external pressure in a graphite resistance furnace in Ar atmosphere at 1950degreesC to high density (up to 98.8%). Contents of alpha-SiC and beta-SiC, as well as the granulometry of the alpha-SiC used, were varying parameters of the initial compositions, the influence of which on densification, microstructure and phase formation during sintering and post-sintering heat treatments was studied. Evolution of microstructure, in particular of the grain morphology occurring due to transformation-controlled grain growth was followed by SEM. The degree of beta-SiC to alpha-SiC phase transformation was measured by means of quantitative XRD using internal standard technique. Fracture toughness of sintered and annealed materials has been determined by the Vickers indentation method and varied in the range 3.6-5.9 MPa m(1/2). Mechanisms of material toughening are discussed in terms of known toughening mechanisms with consideration of residual porosity variation. (AU)