Random chopped fibers in reaction bonded SiC composite: Morphology, etching and reinforcing properties

Random chopped fibers were introduced into SiC/C slurry to improve the mechanical behaviors of reaction bonded SiC ceramics. The distribution, morphology and chemical properties of the siliconized carbon fiber were investigated. The effect of fiber fraction on mechanical behaviors of the reaction bonded silicon carbide composite was studied. The siliconization reaction led to a dense layer of nano and micron SiC particles on the fiber surface. Based on the morphology changes in the acid etching test, a structural model of the siliconized fiber was proposed. The fracture toughness and the flexural strength of the composite were improved by the random chopped fiber, reaching the peak values of 5.1 MPa m0.5 and 416 MPa, respectively, at the fiber fraction of 30 vol.%.

► Random chopped carbon fiber was dispersed into suspension to reinforce RBSCs.
► Structural model on the double layers of the siliconized fiber was proposed.
► Siliconized fiber was etched obviously in the HF/HNO3 acid mixture.
► Fracture toughness was enhanced with the random chopped fibers increasing.