In situ preparation of Al 2O 3–SiC nanocomposites via sol–gel method followed by pressureless sintering

Abstract

Al 2O 3–SiC nanocomposites containing 5 and 10 vol% SiC were prepared via sol–gel method followed by pressureless sintering. AlCl 3·6H 2O and TEOS were used as precursors for alumina and silicon carbide, respectively. The dried gel was heat treated in the range of 800–1600 °C. Two kinds of powders were used to prepare sintered bodies, which were the calcined powder at 800 °C and the synthesized powder at 1600 °C. Green compacts were prepared by cold isostatic pressing, and then pressureless sintered in Ar–12% H 2 atmosphere at 1700 °C. It was shown that β-SiC was in situ formed by means of mullite and carbon reaction at 1600 °C. The density of samples prepared from calcined powder was more than that of samples prepared from synthesized powder. A homogeneous distribution of nanosized SiC particles was synthesized in situ during sintering. The SiC nanoparticles were located predominantly to the interior of Al 2O 3 matrix grains.