| abstract |
PCT No. PCT/AU87/00072 Sec. 371 Date Nov. 1, 1988 Sec. 102(e) Date Nov. 1, 1988 PCT Filed Mar. 13, 1987 PCT Pub. No. WO87/05597 PCT Pub. Date Sep. 24, 1987.A method of forming a dense ceramic product comprised of silicon nitride and silicon oxynitride or aluminum substituted derivative of either in which silica is subjected to a controlled partial carbothermal reduction process in the presence of nitrogen to produce residual silica and silicon nitride, fabricating the resulting material into the desired shape and heating in a nitrogen atmopshere at a temperature of from 1400 DEG C. to 2000 DEG C. with or without pressure to form the product. The silica may conveniently be derived from pyrolysed rice hulls. The product may also comprise silicon carbide, which may be derived from the carbothermal reduction, and a glassy phase. |