High-performance TiN reinforced Sialon matrix composites: A good combination of excellent toughness and tribological properties at a wide temperature range

TiN-doped Sialon matrix composites are potential candidates for high temperature applications due to their excellent mechanical and tribological properties. The objectives of this work are to thoroughly research the mechanical properties and tribological behaviors of the TiN reinforced Sialon composites and reveal their toughening and wear mechanisms. Results show that the fracture toughness can be obviously enhanced by doping TiN. The fracture toughness of the composite with 10 wt% TiN reaches the maximum value of 6.2 MPa m(1/2) and 4.4 MPa m(1/2) at 25 degrees C and 800 degrees C, respectively. Moreover, TiN reinforced Sialon composites exhibit excellent tribological properties at a wide temperature range. Especially for the composite with 30 wt% addition of TiN at 200-800 degrees C, the friction coefficient reduces to 0.46-0.60, and the wear rate decreases about 15-50 times as compared to the material without TiN. In addition, the toughening and wear mechanisms are revealed on the basis of the crack propagation behavior and tribological properties. The crack propagation behavior indicates that crack deflection is the principal toughening mechanism. The enhancement of heat conducting property, mechanical properties, and the tribo-chemical reaction are the main friction-reducing and anti-wear mechanisms.