New Process for Synthesis of Silicon Nitride Powders for Advanced Ceramics

摘要

A new self sustaining flame synthesis process for producing improved silicon nitride powders was experimentally tested. Mixtures of silane and ammonia could not be ignited, but mixtures of silane and hydrazine or silane, ammonia, and hydrazine were found to support stable flames over a wide range of pressures and reagent ratios. Flames with less than the stoichiometric amount of silane produced fine, white, amorphous powders of silicon nitride with specific surface areas from 90-150 m2/g and intrinsic densities of about 3.0 grams/cubic centimeter. Yields greater than 90% and production rates of greater than 10 g/min were achieved. X ray analysis, infrared spectra, and emission analysis for metals confirmed the material to be high purity, Samples typically contained 3% oxygen which was probably introduced in handling.