Tribological properties of carbon fiber toughened SiC prepared by hot pressing sintering

C-sf/SiC composites were prepared by hot press sintering to improve the service performance and wear-resistance of SiC. Surface treatment of short carbon fibers was carried out based on air oxidation and liquid oxidation methods. The dispersion and damage of fibers were investigated after surface treatment. There were less particles and some obvious grooves on the surface of carbon fibers treated by concentrated nitric acid (68%) for 90 min. The optimal air oxidation temperature ranged from 420 degrees to 430 degrees C. The best milling time was 48 h for dispersion uniformity and low injury degree. Composites with low(<= 30 vol%) fiber content were dense, and fibers were evenly distributed in the matrix without agglomeration. The friction coefficients of C-sf/SiC composites decreased with increasing fiber content. Specifically, the friction coefficient of C-sf/SiC composite with 55 vol% C-sf reached to 0.23. The wear rates firstly decreased to the minimum 2.65 x 10(-6) mm(3)/N.m when 30 vol% C-sf was added, and then increased with increasing fiber content. To some degree, this study presented an effective way to enhance the service performance and wear-resistance of SiC.