RECYCLING PROCESSES OF SI WASTE TO ADVANCED CERAMICS USING SHS REACTION

Self-propagating high temperature synthesis(SHS) was applied to recycl e the silicon waste in zinc smelting to the synthesis of silicon nitri de with low cost. It was also tried to use the silicon waste as a flus h heating source for a new material processing of SHS/HIP compaction. Compositionally symmetric gradient materials of the Al2O3/TiC/Ni/TiC/A l2O3 system were fabricated by the SHS/HIP, that uses a chemical oven of Si as a fuel and pressurized nitrogen. These new structured ceramic s showed improved toughness, hardness and strength than the convention al Al2O3 ceramics due to the strong compressive residual stress, which was induced in the outer Al2O3 layer by the thermal expansion mismatc h designed in the graded structure.