FABRICATION AND PROPERTIES OF SiC/SiC COMPOSITES DERIVED FROM CERASET~(TM) SN PRECERAMIC POLYMER

摘要

The fabrication of silicon carbide fiber reinforcedsilicon carbide matrix (SiC/SiC) ceramic matrix composites(CMCs) by a polymer infiltration and pyrolysis (PIP) techniqueis discussed. In PIP processing, fiber performs are infiltratedwith a preceramic polymer, which is then cured and pyrolyzedto form a ceramic matrix. Because the density of a preceramicpolymer (ca. 1.0 g/cm~3)is usually much lower than that of thepyrolyzed matrix, several perform infiltration and pyrolysiscycles must be performed to increase matrix density.Nicalon~(TM) fiber-reinforced composite plates were fabricatedin the as-cured state by (1) vacuum bag/autoclave processing,(2)resin transfer molding, (3) resin infusion of C/SiC performs,and (4) vacuum assisted resin infusion. Lanxide Corporation'sCERASET~(TM) SN preceramic polymer was used in allprocessing techniques to fabricate the SiC/SiC composites plates.Plates fabricated by vacuum bag/autoclave processing, resintransfer molding and vacuum assisted resin infusion with carboncoated ceramic grade Nicalon~(TM) fabric resulted in CMCshaving average room temperature 4-point flexural strengths of265 MPa, 275MPa, and 290MPa, respectively. The best 4-pointflexural strengths, 400 MPa, were achieved via PIP processingto 1000 deg C of the C/SiC coated ceramic grade Nicalon~(TM)fiber-reinforced composite plates were fabricated using infusionof C/SiC performs at pyrolysis temperatures ranging from 1300deg C to 1600 deg C. The maximum room temperatures 4-pointflexural strength, 575MPa, was demonstrated with a plate whichwas pyrolyzed at 1300 deg C. The average 4-point flexuralstrength decreased with increased pyrolysis temperature,presumably due to the degradation of the Hi-Nicalon~(TM)fibers at temperatures greater than 1300 deg C.