Composites for high temperatures

Abstract

The paper will treat materials which are reinforced by fibres, so-called fibre reinforced composites. Such tailorable composites are considered as the most promising candidates in future materials development, especially for application at elevated and up to highest temperatures. The term high temperatures in the sense of the present paper is understood starting from the temperature range above the applicability of epoxies that means above 500 K up to more than 2500 K. The paper considers the fibre materials commercially available today, and in development on the one hand and the matrix materials suitable for combination with the various fibre types on the other. As compatible high temperature matrix materials for carbon fibres only to high temperature polymers and carbon itself can be used. All other high temperature matrix materials need diffusion and reaction barriers surrounding the carbon fibres. The status of preparation of diffusion barriers, their influence on the basic carbon fibre properties and the limitations in application temperature because of limited barrier function will be discussed. Special attention will be drawn to alternative fibres which can be used in metals, glasses, carbides and oxides due to their lower reactivity from the chemical viewpoint. Their disadvantage is a lower heat resistivity and most of them have also lower values for mechanical properties. Finally the possibility to develop fibre reinforced composites from brittle matrix with non-brittle reinforcement fibres is presented as an alternative challenge for high temperature material. © 1988 IUPAC