Properties of SiCf/SiC composites fabricated by slurry infiltration and hot pressing

Abstract

Two-dimensional SiC fibre reinforced SiC ceramic matrix composites (SiC_f/SiC) were fabricated by vacuum infiltration and hot pressing using a 200 nm thick pyrolytic carbon coated Tyranno SA3 fabric and 50 nm sized β-SiC powder. Hot pressing was carried out at 1750°C for 3 h in an Ar atmosphere under a pressure of 20 MPa. Al₂O₃–Y₂O₃–MgO sintering additive (10 wt-%) and polyvinyl butyral resin (45 wt-%) with respect to the matrix SiC were found to be the optimum contents for the high density composite. Vacuum infiltration with a force gradient produced much higher amount of slurry infiltration than simple dipping. Much improved density of 3·02 g cm⁻³, compared to the previous reports, was achieved for the SiC–SiC_f containing approximately 67 vol.-% of fibre. This composite showed a step increase with a stress–displacement behaviour during the three-point bending test due to the fibre reinforcement. The displacement for failure and flexural strength were 0·58 mm and 342 MPa respectively, which were much larger than those for monolithic SiC.