Process for making silicon nitride and powders and articles made therefrom

摘要

A process for making silicon powder or articles of manufacture such as an internal combustion engine valve by comminuting a homogeneous water-base slurry of silicon powder and at least one nitriding agent and permitting the slurry to chemically react for a time sufficient to enable the chemical reaction to substantially reach completion, then reducing the water content sufficiently to form a powder or an article and thence nitriding the article or powder by continuously varying the temperature over the range of 1000 DEG C. to 1450 DEG C. using a nitriding gas comprising nitrogen, hydrogen and helium and maintaining a constant nitriding gas composition throughout the nitriding cycle.