| 摘要 |
<p>A composite boron nitride material comprises a base (1) mmade of graphite, a boron nitride layer (2) covering the surface of the base (1) and a diffusion layer (3), made of a boron cpd. and graphite lying between (1) and (2). The diffusion layer (3) is a diffusion layer of boron nitride and graphite, of boron nitride, boron and graphite, or of boron nitride, boron carbide, boron and graphite. The composite boron nitride material is produced by bringing a graphite moulding into contct with a gas mixture of an oxygen-containing boron vapour and a nitrogen-containing gas, and heating them at 1400-200 deg.C. This process provides a boron nitride-covered graphite in which boron nitride and carbon are firmly bonded. Additionally a boron-nitride covering layer can be formed on the surface of the resulting composite. Ceramic fibres can be used as a base instead of graphite. They are firmly combined with boron nitride physically. Boron nitride-covered ceramic fibres can be produced by the above-mentioned process by replacing graphite by a mixture of graphite and ceramic fibres. When carbon fibres are used as the base, boron nitride-covered fibres are produced by using boron nitride fibres instead of carbon fibres.</p> |
