| 摘要 |
Silicon nitride whiskers are produced by heating a mixture of silicon and silica to above 1200 DEG C. to form a silicon containing vapour which is mixed with nitrogen in the presence of carbon and a small proportion of hydrogen and contacting the mixture with a substrate heated to at least 1200 DEG C. to form silicon nitride whiskers on the surface. The finely divided silicon/silica mixture may be blended with about 5% of binder and made into pellet form. The nitrogen and silicon vapours may be continuously mixed in the reaction zone and the silicon vapour may be carried to the reaction zone by a stream of inert gas which is passed through the silicon/silica mixture. Hydrogen, which may be introduced in the inert gas stream, is present in the proportion of 0.1 to 10% by volume of the nitrogen present, carbon may be present as carbon cloth which may be used as the substrate although mullite is prefered for this purpose. The carbon and hydrogen may alternatively be introduced with the nitrogen in the form of a volatile hydrocarbon. |
