硝酸塩系焼結助剤添加Si_3N_4/SiC複合材の焼結性及び機械的性質に及ぼす焼結法の影響

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The effects of various sintering methods, such as pressureless-sintering, hot-pressing and spark-plasma-sintering, on the densification and mechanical properties of Si_3N_4/(0-30 mass%) SiC composites were examined. Two sets of starting powders mixed with nitrates and oxides as sintering additives, respectively, were used. By pressureless-sintering, density of the Si_3N_4/SiC composites generally decreased with increase in SiC content, and the composites with nitrate additives were denser than those of oxide additives at the same amount of SiC. The Si_3N_4/SiC composites sintered by hot-pressing and spark-plasma-sintering were fully densified regardless of the type of sintering additives and amount of SiC. The mechanical properties strongly depended on the amount of SiC and sintering additives, i.e., on the sintered density and morphology of Si_3N_4 grains. The mechanical properties of the monolithic Si_3N_4 and the Si_3N_4/10 mass%SiC composite fabricated by pressureless-sintering were nearly the same as those of hot-pressed specimens.
1998-06-01