アルミナとイットリアを添加した炭化ケイ素の水系プロセッシング,加圧焼結及び力学特性

概要

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Submicrometer-sized α-SiC powder was mixed in an aqueous solution at pH 5.0 with the following Al_2O_3 (1-2 vol% against SiC)-Y_2O_3 (0.94-1.6 vol%) sintering additives: sample A-Al_2O_3 powder plus Y_2O_3 powder, sample B-Al_2O_3 powder plus Y_2O_3 powder and polyacrylic acid dispersant, sample C-Al_2O_3 powder plus Y^<3+> ion adsorbed and sample O-Y^<3+> 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℃ 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 ap sample B. The sinterability of samples A and B was comparable to that of SiC hot-pressed with Al_2O_3. Dense SiC with Y_2O_3 or Al_2O_3 plus Y_2O_3 showed the following excellent mechanical properties: average four-point flexural strengths of 565-719 Mpa, fracture toughness of 5.0-6.2MPa・m^<1/2>, Weibull modulus of 5.4-11.4 and Vickers hardness of 19-22 Gpa. Suppression of grain growth in SiC enhanced the mechanical properties.
社団法人日本セラミックス協会の論文
2005-02-01