Tribological behaviour and wear resistance of a SiC–MoSi2 composite dry sliding against Al2O3

A composite consisting of 30 vol.% MoSi2 particles in SiC matrix was prepared by liquid phase sintering carried out with the aid of small additions of Al2O3 and Y2O3 and then submitted to dry sliding tests using alumina as the counterfacing body under different conditions of applied load (15, 30 and 50 N) and relative speed (0.5, 1.0 and 2.0 m s−1), for a constant sliding distance of 10 km. Friction coefficient and system wear of the couple were continuously recorded during the tests. Phase composition and microstructure of the selected materials were analyzed by X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM), electron probe microanalysis (EPMA) in the energy dispersion mode (EDS) and Vickers microhardness measurements (MHV). The surface finishing and roughness of the as-prepared materials were evaluated by means of stylus profilometry. Volume wear rates were determined by measuring the weight loss for the composite and the depth of wear track for alumina after each test. Moreover, wear debris were collected and then analyzed by means of XRD, SEM and Raman spectroscopy (RS). The effects of applied load and sliding speed on the wear rate and damage mechanisms were analyzed and discussed for both composite and alumina.