Novel processing approach to polymer‐derived ceramic matrix composites

Abstract

AbstractThe 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.