硝酸塩を焼結助剤としたSi_3N_4及びSi_3N_4/SiC複合材の常圧焼結

概要

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The effect of nitrates as sintering additives on the densification of Si_3N_4 based ceramics by pressureless sintering was compared with that of oxide additives. The surface of Si_3N_4 particles milled with a methanol solution of Al and Y nitrates, was coated with a layer containing Al, Y and O. Homogeneous distribution of sintering additives increased the sinterability of Si_3N_4. Monolithic Si_3N_4 with nitrate additives could be sintered to 94% T.D. at 1500℃. Furthermore, after pressureless sintering at 1750℃ for 2h in N_2, the bulk density of a Si_3N_4/20 mass%SiC composite reached 95% T.D. with nitrate additives. The enhancement of densification in the case of nitrate additives was attributed to the enhancement of primary particle rearrangement due to the homogeneous distribution of liquid phase, a consequence of the homogeneous distribution of sintering additives, during sintering.
1997-02-01