Dry sliding wear behavior of MoSi2-Mo5Si3-Mo5SiB2 composite at different temperatures and loads

MoSi2-Mo5Si3-Mo5SiB2 composite is a kind of potential wear resistance material in high temperature environments. However, it is not yet understood how the dry sliding wear properties of the composite. In this work, a series of ball (Si3N4)-on-disk (composite) sliding wear tests were conducted to evaluate the tribological properties of the composite at different temperatures and loads. The results show that the temperature and load have a slight influence on the wear rate of the composite, while the coefficient of friction (COF) is strongly dependent on the temperatures and loads. The COF and wear rate are (0.34-0.62) and (6.4-7.5) x 10(-6) mm(3) N-1 m(-1) at 25-1000 degrees C, respectively. The wear mechanism is dominated by the brittle fracture wear below 400 degrees C, then transforms to the oxidative wear (600-1000 degrees C), and the plastic deformation (1000 degrees C). In additional, the increasing loads (2.5-10 N) lead to a severer plastic deformation tribolayer on the worn surface, which causes low COFs (0.30-0.56) as well as low wear rates (7.38-7.54 x 10(-6) mm(3) N(-1)m(-1)) at 1000 degrees C, and the corresponding wear mechanisms exhibit the adhesive and oxidation wear. The composite shows a promising application as tribological components at elevated temperature in oxidizing environment owing to the development of a protective oxide layer or a plastic deformation tribolayer on the top of the wear surface.