Rapid sintering of alumina in low pressure RF plasma

Three kinds of high-purity Al2O3,, powders, whose average particle size is 0.1, 0.3 and 3.0 mu m respectively, were used as the starting power, and their compacts were fired in the radio-frequency plasma generated at a pressure of 80 Pa using N-2? as the working gas. Experimental results show that the 0.1 and 0.3 Irm powder compacts can be sintered to nearly the theoretical density within 60 s and this sintering is almost finished in the heating period. It is concluded that the mechanism of liquid sintering, the electric charge effect of Al2O3 powder, and the effect of temperature gradient in the compacts can affect simultaneously on the rapid densification of the compacts in the plasma sintering.