Silicon nitride-contg. refractories with low permeability - prepd. by reaction sintering ferrosilicon nitride and silicon powders

摘要

Porous, reaction-sintered, moulded bodies based on silicone nitride are made by nitriding silicon metal particles and additives and then sintering. The starting materials comprise 70-95 pts. wt. ferrosilicon nitride powder and 30-5 pts. wt. silicon metal powder. Pref. the ferrosilicon nitride contains 65-80 (70-80) wt.% silicon nitride and the rest is essentially free iron. The nitriding is performed at max. temp. of 1350 degrees C (1250-1350 degrees C) and the sintering at about 1500 degrees C for 4-8 hrs. Used as a refractory, the material combines a high porosity, and therefore a low heat conductivity, with a low permeability, and therefore a good corrosion resistance, to gases, slags and molten metals. The material can be produced without pressurised sintering.