PREPARATION OF HIGH-STRENGTH CERAMIC FIBER-REINFORCED SILICON-NITRIDECOMPOSITES BY A PRECERAMIC POLYMER IMPREGNATION METHOD

High strength ceramic composites, reinforced with Si-N and Si-B-O-N ce ramic fibres, were prepared by the preceramic polymer impregnation met hod. Low-viscosity polysilazanes with a 70-90 wt% ceramic yield, were used as a matrix precursor. To obtain dense composites, the impregnati on, curing and firing processes were repeated. Three-point flexural st rength of the UD and 2D (cross-ply) ceramic fibre reinforced ceramic c omposites were shown to be as high as 1000 and 600 MPa, respectively. This resulted from the dense silicon nitride matrix and controlled fib re/matrix interface. (C) 1997 Elsevier Science Limited and Techna S.r. l.