Silicon carbide articles reinforced with short graphite fibers

US6231791A · kind A · utility

Assignee

• SGL Technik GmbH · DE

Inventors

• Michael Heine · Meitingen, DE
• Udo Gruber · Neusäß, DE

Key dates

• Filing date: Apr 15, 1999
• Grant date: May 15, 2001
• Expiry date: Apr 15, 2019

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F16D2200/0047
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A composite material article reinforced with high strength short graphite fibers and having a matrix substantially consisting of silicon carbide is prepared which has an elongation at break of 0.25 to 0.5% and thus exhibits quasi-ductile failure behavior. The short reinforcing graphite fibers are enclosed by at least two shells of graphitized carbon which have been obtained by impregnation with carbonizable impregnating agents and subsequent carbonization. The shell closest to the graphite fibers contains no cracks. The outermost shell is partially converted into silicon carbide. The starting material used comprises long or short fiber prepregs, which are first carbonized, then subjected at least once to an operation consisting of impregnation with a carbonizable impregnating agent and recarbonization, then graphitized at a temperature of up to a maximum of 2400.degree. C. and then comminuted to yield a dry material for the production of a precursor article. This dry material is then mixed with a binder having a high carbon content and the mixture is compression molded to yield a green article. The green molding is then carbonized and afterwards infiltrated with liquid silicon, wit…