α-SiCの常圧焼結におけるホウ素系助剤の液状添加効果

概要

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The effect of boron dispersion on the sintering of SiC was studied by comparing the addition of soluble compounds (B_2O_3B_<10>H_<12>C_2 and NaBF_4) in fluid form with that of amorphous boron powder. A large part of the boron in the fluid additions disappeared below 1550℃. The residual amount of boron was nearly constant up to the sintering temperature (2050℃). The density values for the residual boron contents were identical with that for powder boron addition. NaBF_4 gave the low mechanical strength, because of the remaining sodium till high temperature. However, in B_2O_3 or B_<10>H_<l2>C_2, the mechanical strength was higher than 55 kg/mm^2 (room temperature strength for boron powder addition). B_<10>H_<l2>C_2 addition resulted in high strength (max. 82 kg/mm^2, mean 68 kg/mm^2, min 44 kg/mm^2 : density 3.16 g/cm^3), even for a small amount of boron content (0.11 wt%). The weak strength (40-50 kg/mm^2) was attributed to the large pore defects (O.05-0.2 mm) which were considered to be formed in the initial stage of sintering by the rearrangement of Si C particles. In fluid addition, it may be assumed that the homogeneity of boron dispersion was improved, resulting in the suppressed particle rearrangement.
社団法人日本セラミックス協会の論文
1988-02-01