Nitridation of high purity, laser-synthesized silicon powder to form reaction bonded silicon nitride

摘要

The nitriding kinetics of high purity 0.2 (mu)m Si powders made from laser heated SiH(sub 4) gas were studied with thermogravimetric analysis (TGA), X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Compared to conventional reaction bonded Si(sub 3)N(sub 4) (RBSN), nitridation occurred more rapidly and at lower temperatures (e.g. > 97% conversion in less than ten minutes at 1250(degrees)C). Samples exhibited unusual reverse reaction gradients with more nitridation occurring inside of pellets than at the outer surfaces. Exposure to methanol retarded nitridation.