Fabrication of SiC Fiber Reinforced SiC Matrix Composites Using CERASET® SN Preceramic Polymer
D. Miller
The fabrication of silicon carbide fiber reinforced silicon carbide matrix (SiC/SiC) composites by various processing techniques using a polymer infiltration and pyrolysis (PIP) approach are discussed. In PIP processing, fiber preforms are infiltrated with a preceramic polymer, whcih is then cured and pyrolyzed to form a ceramic matrix. Because the density of a preceramic polymer (ca. 1.0 g/cm3) is much lower than that of the pyrolyzed matrix product, several preform infiltration and pyrolysis cycles must be performed to increase matrix content, i.e., reduce matrix porosity. Several methods were used to fabricate Nicalon ® fiber reinforced composite plates with the polymer matrix in the as-cured state: vacuum bag/autoclave processing, resin transfer molding, vacuum assisted resin infusion, and plymer infiltration of preforms consisting of Nicalon ® fibers with a C/SiC duplex coating.
Lanxide's CERASET® SN preceramic polymer (now called KiON Ceraset Polyureasilazane) was used in all processing techniques to fabricate the SiC/SiC composite plates. Plates fabricated by vacuum bag/autoclave processing, resin transfer molding, and vacuum assisted resin infusion using carbon coated ceramic grade Nicalon ® fabric resulted in average 4-point flexural strengths of 265 MPa, and 290 MPa, respectively. The highest average 4-point flexural strength of 400 MPa was achieved via PIP processing of a C/SiC coated ceramic grade Nicalon® preform. Plates fabricated by the four techniques possessed fiber volumes of 36%. the detailed procedures for fabricated SiC/SiC composites by each processing technique, and their respective mechanical properties, are discussed in this paper.