Friction and wear mechanisms of K2O-B2O3-Al2O3-SiO2-MgO-F glass-ceramics

Among various brittle materials, the mica-based glass-ceramics are of greater scientific interest, because of their machinability. Considering the potential of these materials as dental implants, an understanding of the wear behavior in oral environment is important. In the present investigation, K2O-B2O3-Al2O3-SiO2-MgO-F glass-ceramics containing about 70% crystals, heat treated at 1040 °C for 12 h was subjected to fretting against steel ball in artificial saliva (AS) environment. In order to elucidate the influence of environment on the friction and wear behavior, control experiments were also performed under dry ambient conditions. A systematic decrease in wear rate with test duration was recorded with a minimum wear rate of 10−5 mm3/Nm after 100,000 fretting cycles in AS medium. Scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) analysis indicated the formation and brittle fracture of tribochemical layer in AS medium, whereas mica crystal pull-out was a dominant mechanism in dry conditions.