コロイドプロセスによる高性能炭化ケイ素の合成

Abstract

The combination of thermodynamics of colloidal suspensions and the DLVO theory succeeded in constructing a colloidal phase diagram in a map of surface potential and solid content of particles of 10-1000 nm diameters. The experimentally-determined packing density agreed with the prediction from the phase diagram. A phase transition from a dispersed suspension to a flocculated suspension during pressure filtration occurred when an applied pressure exceeded a critical value. Based on the colloidal phase transition, new filtration theories were developed for a flocculated suspension. Multi component colloidal suspensions of the 800 nm SiC-30 nm SiC-150 nm Al2O3-Y ions system were heterocoagulated to distribute uniformly the sintering additives （Al2O3 plus Y2O3） around SiC particles. The green compacts were highly densified above 99％ theoretical density by hot-pressing at 1950℃ and the sintered SiC provided flexural strengths above 1000 MPa.