Abstract
α-Si3N4 whiskers were grown by heating a mixture of “silica black” ore with additional carbon in a tightly capped crucible (30cm3 volume) in flowing nitrogen at 1400°C for 40h. The nitrogen flow rate greatly affected the yield and shape of the whiskers. A large mass of whiskers was produced downstream on the outside surface of the crucible when the nitrogen flow rate was 9cm⋅min-1. The resulting whiskers had rod-and plate-like forms with an average size of 10 to 40μm thick and several hundreds μm long. Thin whiskers and fibers were formed downstream on the outside bottom of the crucible and in lower temperature regions, respectively. A droplet containing mainly Fe and Si was formed on the tip of many whiskers, suggesting occurrence of a VLS (Vapor-Liquid-Solid) growth mechanism.
