M.H. Lewis        

Anales de la Mecánica de la Fractura, nº 11 . 1994 . Pág. 18 -26
Ver (.pdf): Anales11-002

Resumen: A survey is presented of research aimed at an understanding of the relation between microstructure, interface properties and mechanical behaviour of a range of silicate (glass ceramic) and nitride matrix composites. For silicate CMCs, hot-pressing cycle (P/T) in relation to matrix chemistry and fibre type is critica! In avoiding mechanical and chemical damage of fibres with consequent reduction in ultimate CMC strength. 'Graceful' failure, typified by 3 stage stress-strain curves, may be obtained for interface debond energies and shear stresses T up to -20 Jm-2 and -50 MPa, respectively. Interface-oxidation-induced property degradation occurs at intermediate temperatures ( 400-800 °C) but is suppressed at higher tempt!ratures by passive oxidation of SiC fibre ends which prevents further carbon interface removal by channelled reaction. Higher temperature SiC (Textron CVD) monofilament based CMCs with Si,N~ (SRBSN) matrices have been fabricated using tape-cast matrix preforms. Although oxidation of carbon interfaces is a limiting problem for creep and stress rupture, these properties are superior to turbine superalloys.

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Centre for Advanced Materials Technology University of Wanvick, Coventry CV4 7 AL United Kingdom