Novel processing approach to polymer‐derived ceramic matrix composites

The rheological properties of commercially available polycarbosilane, SMP-10, were analyzed as a function of temperature, to guide development of thermal treatment processes for the improved yield and functionality of polymer ceramic precursors. The curing onset temperature for SMP-10 was determined to be as low as 100°C for a heating rate of 1°C/min enabling a heat treatment process at 90°C, where low molecular weight oligomers volatilize from the liquid precursor prior to curing. By driving off the low molecular weight oligomers before fabrication of a composite, the mass yield of SMP-10, from a room temperature liquid state was increased from 77% to 83%. The development of B-staging processes, or a semicure of SMP-10, were also demonstrated. B-staging processes were then applied to polymer infiltration and pyrolysis processing and compared with traditional wet layup CMC processing. It was determined that B-staging processes did not adversely affect ceramic matrix composite fabrication. B-staged processing methods were determined to result in less waste, allow ply-by-ply control of matrix compositions, and enable time independent processing when compared to traditional wet layup processing methods.