Preparation of silicon-titanium-carbon-oxygen fabric/mullite filler/polytitanocarbosilane laminates by polymer impregnation and pyrolysis method

Abstract

A polytitanocarbosilane (PTC, 20-50 mass %)-xylene solution was infiltrated into a porous, laminated woven fabric of 21-33 vol% Si-Ti-C-O fibers including 26-46 vol% mullite powder (filler) and decomposed at 1000°C in an argon atmosphere. This polymer impregnation and pyrolysis method (PIP) was repeated eight times to produce a laminated composite of 68%-85% of theoretical density. The effects of the polymer concentration and the fraction of mullite filler on the densification rate and microstructure of the layered composite were studied. The pseudoductility of the densified composite, as measured using four-point flexural testing, was caused by buckling after the elastic deformation and was followed by delamination along the direction of the layered fabric. The strength and the energy of fracture were enhanced by controlling the incorporation of mullite filler in the filament yarn (formation of a narrow pore-size distribution) and densification with a low-viscosity PTC solution. The composite with a higher strength provided a higher energy of fracture. The maximum energy of fracture reached 22 kJ/m2 in the composite with 330 MPa of strength in four-point flexure.