Plasma Sintering of Ceramics

Abstract

Although the first plasma sintering of ceramics was reported a number of years ago,^1,2 there has been relatively little follow-up work.^3–8 Bennett et al.¹ inserted a quartz glass or alumina tube through a waveguide, excited plasmas at 2450 MHz at gas pressures of 100-7000 Pa, and sintered Al₂O₃ and a few other ceramic powders. They heated small pressed compacts for various lengths of time at various temperatures in the plasma and at the same times and temperatures in a conventional furnace. At all temperatures, that is, 1300°–1700° for Linde A alumina in air, the densities of the plasma sintered pellets were significantly higher than those of the conventionally sintered pellets. Moreover, the grain size was smaller and the strength was higher for the plasma sintered specimens. They observed that various gases gave the same densities at the same specimen temperatures and times.