Mechanical properties of short carbon fiber-reinforced TiC composites produced by hot pressing

Abstract

In order to improve the strength and toughness of TiC materials, especially the elevated temperature strength so as to extend the applications in elevated temperature environment, TiC composites containing 20 vol.% short carbon fiber (C f/TiC) were produced by hot pressing. The short carbon fibers were uniformly distributed in the TiC matrix by wet ball-milling mixing. The hot-pressing technique for C f/TiC composites was optimized with respect to hot-pressing temperature and pressure, and the most suitable technique is vacuum sintering at 2100 °C under 30 MPa for 1 h. With carbon fiber addition, not only the room temperature strength and fracture toughness of TiC are remarkably increased, but the elevated temperature strength is increased as well. The flexural strength of the C f/TiC composite is 593 MPa at room temperature and 439 MPa at 1400 °C. The strengthening effect of the carbon fibers is estimated using a slightly modified role-of-mixture formulation, and the toughening effect is also calculated based on the toughening mechanisms of crack bridging, fiber pullout and crack deflection. The calculated results of the strength and fracture toughness of the composite agree well with the experimental results.