Friction and wear behavior of cemented carbide self-matching pairs under different water lubrication conditions

The friction and wear behavior of WC based cemented carbides ring-ring samples in different water environ- ments were systematically tested. The average grain size of WC is 1.2 mu m and the mass fraction of binder Co is 8%. The water environments include distilled fresh water, artificial seawater with NaCl mass content of 4%, and sediment water with SiO2 mass content of 0.6% and average particle size of 88 mu m. The friction torque was measured for each friction pairs at different speeds and specific pressure loads. The surface morphology of the friction pairs before and after the test were observed by a scanning electron microscope, and the weight losses were also measured by a balance. The test results suggest that the friction coefficient of all the sample pairs decreases exponentially with the increase of load at proper revolution speed. In the range of 4-10 MPa specific pressure, the friction coefficient of the bearing during stable operation is between 0.01-0.02. The wear rate of the stationary ring is about 3 times that of the matching rotary ring, no matter in the environment of artificial seawater, distilled fresh water or sediment water lubrication medium. However, the wear rates of the samples in artificial seawater are higher than those of the two rings friction under the same speed and load conditions in the other two water environments. SiO2 particles in the sediment water has no effect on the bearings wear rate. The wear of cemented carbide self-matching pair bearings is mainly the peeling of WC particles caused by the alternating contact and friction force or plowing of WC abrasive particles. The corrosivity of artificial seawater can aggravate the peeling of WC particles. The results and conclusions of this study can provide a meaningful reference for the design of cemented carbide bearings utilized in water lubrication environment.