FIBER-REINFORCED CERAMIC MATRIX COMPOSITES PROCESSED BY A HYBRID PROCESS BASED ON CHEMICAL VAPOR INFILTRATION, SLURRY IMPREGNATION AND SPARK PLASMA SINTERING

摘要

The fabrication of multidirectional continuous carbon and silicon carbide fiber reinforced Ceramic Matrix Composites by a new short time hybrid process was studied. This process is based, first, on the deposition of fiber interphase and coating by chemical vapor infiltration, next, on the introduction of Si_3N_4 powders into the fibrous preform by Slurry Impregnation and, finally, on the densification of the composite by liquid-phase Spark Plasma Sintering (SPS). The homogeneous introduction of the mineral charges into the multidirectional fiber preforms was realized by slurry impregnation from highly concentrated (> 32 %vol.) and well dispersed aqueous colloid suspensions. The following densification of the composites by spark plasma sintering was possible with a 2 minutes holding period at 1650°C. The chemical degradation of the carbon fibers during the fabrication was prevented by adapting the sintering pressure cycle and the pressure media. The composites elaborated are dense. Our carbon fiber reinforced ceramic matrix composites have a damageable mechanical behaviour with a bending stress at failure around 250 MPa. Silicon carbide fiber reinforced ceramic matrix composites have a brittle mechanical behaviour with a bending stress at failure around 150 MPa. Microstructural analyses were conducted to explain the mechanical properties obtained. One main important result of this study is that spark plasma sintering can be used in some hybrid processes to densify multidirectional continuous fiber reinforced ceramic matrix composites.