Refractory metal or metal-based ceramic coated ceramic or metal fibres for metal matrix composite

摘要

Fibre of tungsten, Inconel, alumina, alumina-silica, alumina-boria-silica, boron, titanium diboride, silicon carbide, silicon nitride, or boron nitride is coated with molybdenum, tantalum, tungsten, niobium, zirconium, hafnium, or titanium, the coating being uniform and having a grain size of 5-75 nanometres and one or less visible voids per 0.5 square microns of area, a visible void being at least 5 nanometres in size. Also claimed is a process for coating ceramic, metal, or carbon fibres in continuous tows or bundles (20) by positioning them in the path of a plasma (19) of atoms and ions created by applying sufficient current to a metal cathode (13), the plasma causing the fibres to billow and the plasma condensing on them to form a refractory metal or metal-based ceramic coating. The fibre is alpha-alumina or alumina-boria-silica. It is 5-150 microns in dia., more pref. 5-50 microns. The coating is 20-500 nanometres thick, more pref. 50-300 nanometres, and has a grain size of 15-25 nanometres. It is esp. yttrium oxide. An inert gas is supplied to the plasma, esp. argon, krypton, xenon, or helium. Alternatively, a reactive gas may be supplied, esp. oxygen, nitrogen, ammonia, a hydrocarbon, or a boron-contg. gas.