アルミニウムイソプロキポシド,α-Si_3N_4及びβ-SiCから得たβ-サイアロン(z=1)-SiC複合体の常温強度及び破壊靭性

概要

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β-sialon (z=1) -SiC (50 mass%) composite was fabricated by hot-pressing a spray-dried mixture of α-Si_3N_4, SiC and aluminum-iso-propoxide solution. The bending strength and fracture toughness ( K_<IC>) of sinterd bodies were investigated by comparing with β-sialon (z=1) without SiC. Both strength and K_<IC> were increased from 1000 to 1560 MPa and 3.5 to 4.5 MPa・m^<l/2> by SiC addition, respectively. About a half of tested specimens fractured from internal defects and the other fractured from surface flaws. The strength of the specimens which fractured from internal defects increased from 1180 to 1580 MPa. This value coincided with that derived from the equation K_<IC> =σ_fY√<c>, due to the same size of defects as fracture origins (c) . In case of the specimens which fractured from surface flaws, the strength increased from 900 to 1540 MPa. The increase in K_<IC> Presumably resulted in decreasing the size of machining flaws as fracture origins. It was considered that as the transgranular fracture occurred in the β-sialon matrix of this composite, homogeneously dispersed SiC particles immediately brought small crack deflection. This might be a reason for increase in both strength and K_<IC>.
社団法人日本セラミックス協会の論文
1996-08-01