Abstract
Consolidation of non-crystalline Si-C-N powders has been tried by hot isostatic pressing without sintering additives, in order to fabricate dense non-oxide ceramic monoliths without the crystallization. A polyvinylsilazane polymer was thermally cross-linked at 250°C and pyrolyzed at 1050°C under Ar atmosphere, which resulted in the formation of the ceramic state with a chemical composition of Si1.0C1.6N1.3 in atomic ratio. The pyrolyzed powders were die-pressed into rectangular bars at room temperature and consolidated by hot isostatic pressing at 1400°C-900 MPa. A ceramic monolith with a level of almost full density was obtained by the consolidation, although a few pores of about 1 μm still remained in the cross-sectional structure. The amorphous phase was significantly maintained in the consolidated sample. In the compression tests of the sample, only slight plastic deformation was observed at 1400°C and 1500°C in spite of high compressive stress over 1600 MPa. On the other hand, the sample showed plastic deformation at 1600°C.
