Effect of the method of fabricating SiC, Si_3N_4, and AlN specimens on their resistance to high-temperature oxidation

摘要

The methods of high-pressure sintering (5 GPa)and, for comparison, conventional hot pressing are used forfabricating high-density specimens from SiC, Si_3N_4, and AlNwith the use of activating additives and without them. The high-temperature oxidation is studied by the method ofthermogravimetry at 1400 deg C with a l50-min hold. Theintroduction of additives in order to activate the sinteringincreases the resistance of hot-pressed specimens to high-temperature oxidation and does not influence the stability ofmaterials obtained in a high-pressure apparatus. The corrosionresistance of materials sintered under a high pressure turns outto be much higher than that of hot-pressed materials, which isconnected with the formation of superfine-grained densely fit oxide films.