Patent ID: 6849213

Claim:
A method comprising, heat treating in nitrogen a green body comprising from 40 to 90 mass % of metal silicon particles having an average particle diameter of from 1 to 30 μm and from 10 to 50 mass % of a pore-forming agent to from a porous product comprising substantially silicon nitride by converting the metal silicon to silicon nitride, wherein heat-treating comprises first maintaining the green body in a nitrogen atmosphere at a temperature of from 1,000 to 1,400° C. for from 5 to 24 hours, and then maintaining the green body at a temperature of from 1,450 to 1,800° C. for from 2 to 5 hours: wherein the total amount of metal silicon particles and pore-forming agent in the green body is at least 90 mass %, and wherein the pore-forming agent decomposes during heat treatment.