Effects of fiber surface treatments on mechanical properties of T700 carbon fiber reinforced BN–Si3N4 composites

T700 carbon fibers were surface treated by air oxidation as well as heat treatment and characterized by SEM, XPS and tensile test. As-received and treated carbon fiber reinforced BN–Si3N4 matrix composites were fabricated by precursor infiltration and pyrolysis method, and the mechanical properties of the composites were determined and compared. The effects of the fiber surface on the mechanical properties were investigated. Both air oxidation and heat treatment methods can remove the size on the fiber surfaces. The oxidized fiber shows a rough surface, and the heat treated fiber shows a relatively smooth surface. The mechanical properties of oxidized fiber reinforced composite are visibly improved, and those of heat treated fiber reinforced composite are hardly changed. Different fiber surfaces result in different interfaces between fiber and matrix and different mechanical properties of the composites.