Effects of nitrogen pressure and diluent content on the morphology of gel-cast-foam-assisted combustion synthesis of elongated β-Si_3N_4 particles

摘要

Elongated β-Si_3N_4 particles were prepared by gel-cast-foam-assisted combustion synthesis, which is a combination method of gel-casting-foam method and combustion synthesis. Gel-casting-foam method was used to prepare starting powder green body of high porosity and sufficient strength. Combustion synthesis reaction was conducted on the as-made green body. The effects of N_2 pressure and diluent content on the combustion velocity, conversion rate and morphology of the resulting particles arc studied. With high porosity (~80%), the conversion rate more than > 90% was achieved at low N_2 pressure (1.5 MPa) and low diluent content (even nil). In the epoxy composites, elongated β-Si_3N_4 powder was confirmed a better filler than its equiaxed counterpart in improving the thermal conductivities of the resultant composites.