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Home  >  Journal list  >  Journal of the Ceramic Society of Japan ( 2003 - 2007 )  >  Vol.113  No.1314 (February) (2005)  >  pp.143-148

Journal of the Ceramic Society of Japan ( 2003 - 2007 )
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Aqueous Processing, Hot-Pressing and Mechanical Properties of Silicon Carbide with Al2O3 and Y2O3

Nobuhiro HIDAKA1), Yoshihiro HIRATA1), Xu Hong WANG1) and Shuhei TABATA1)
1) Department of Advanced Nanostructured Materials Science and Technology, Graduate School of Science and Engineering, Kagoshima University

  Submicrometer-sized α-SiC powder was mixed in an aqueous solution at pH 5.0 with the following Al2O3 (1-2 vol% against SiC)-Y2O3 (0.94-1.6 vol%) sintering additives: sample A-Al2O3 powder plus Y2O3 powder, sample B-Al2O3 powder plus Y2O3 powder and polyacrylic acid dispersant, sample C-Al2O3 powder plus Y3+ ion adsorbed and sample D-Y3+ ion adsorbed. The prepared suspensions were consolidated by filtration through a gypsum mold. Green compacts were densified to a 96.2-99.3% relative density at 1800-1950°C under a pressure of 39 MPa for 2 h in an Ar or reduced atmosphere. The sinterability of SiC became higher in the following order: sample D<sample C<sample A≈sample B. The sinterability of samples A and B was comparable to that of SiC hot-pressed with Al2O3. Dense SiC with Y2O3 or Al2O3 plus Y2O3 showed the following excellent mechanical properties: average four-point flexural strengths of 565-719 MPa, fracture toughness of 5.0-6.2 MPa•m1/2, Weibull modulus of 5.4-11.4 and Vickers hardness of 19-22 GPa. Suppression of grain growth in SiC enhanced the mechanical properties.



Keyword:
Silicon carbide, Aqueous processing, Hot-pressing, Strength

Received: September 13, 2004
Accepted: November 26, 2004 , Published online: February 01, 2005
Copyright (c) 2005 The Ceramic Society of Japan

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