Ceramic-fibre composite hot gas tube - with ceramic matrix formed from silicon polymer and fibres of inorganic materials or mixts., used for e.g. vehicle exhaust tube

摘要

A ceramic hot gas tube is made of a ceramic-fibre composite material in which (a) the fibres consist of inorganic materials (e.g. C, SiC, SiO2, Al2O3, Si3N4 or Al2O3, SiO2, B2O3) or their mixts. or cpds.; and (b) the ceramic matrix is formed from a Si polymer ceramic precursor by cross-linking and pypolysis. The matrix is pref. produced from a silane, carbosilane, vinylsilane, silazane and/or siloxane and may contain upto 90 wt.% ceramic powder, pref. SiC, Si3N4, BN and/or Al2O3. The fibres (opt. woven) are pref. infiltrated with a slip of the matrix precursor and opt. the powder and, after pref. winding or laminating, the precursor is hardened using a chemical cross-linker or using elevated pressure and temp., followed by pressure-less thermal conversion to a ceramic material. USE/ADVANTAGE - The pipe is useful as an aircraft or vehicle exhaust tube. It is resistant to high temps. (at least 500 deg.C), corrosion and oxidn. has higher fracture toughness than monolithic ceramics, has low density (below 2.5 g/cu cm), can be mass produced and is self-supporting even when of large size (e.g. 0.5 m dia. and 1.5 m length). (3pp Dwg.No.0/0)