Mechanical Properties of SiC Processed with Nanometer-Sized Powder and Polytitanocarbosilane
A bimodal powder system of 800 nm SiC (75 vol%) - 30 nm SiC (25 vol%) was dispersed at 20 vol% solid in a 0.3 M Y(NO3)3 solution containing 0.2 μm Al2O3 and 1.0 mg/m2 polyacrylic acid (PAA: dispersant). The SiC (97.6 vol%)-Al2O3 (1.2 vol%)-Y2O3 (1.2 vol%)-PAA system suspension was consolidated by casting in a gysum mold. Polytitanocarbosilane (PTC) of 3 vol% was infiltrated into the SiC compact calcined at 800 °C to increase the mechanical properties and Weibull modulus. Both the calcined powder compacts with and without PTC were hot-pressed to relative density above 97 % at 1950 °C. The hot-pressed SiC with or without PTC provided the following excellent mechanical properties: average four-point flexural strength of 911 and 812 MPa, fracture toughness of 5.2 and 6.0 MPa·m1/2, and Weibull modulus 11.3 and 5.8 for PTC addition and no addition, respectively. The PTC addition was effective to decrease the shape factor of flaw and increased the strength and Weibull modulus.
Katsutoshi Komeya, Yohtaro Matsuo and Takashi Goto
N. Matsunaga et al., "Mechanical Properties of SiC Processed with Nanometer-Sized Powder and Polytitanocarbosilane", Key Engineering Materials, Vol. 352, pp. 73-76, 2007