FRICTION AND WEAR PROPERTIES OF Ni-FREE Zr-BASED BULK METALLIC GLASSES IN SIMULATED BODY FLUID

In the last decade, bulk metallic glasses (BMGs) emerge as a new class of metallic materials with disordered atomic structure. Especially, Zr-based BMGs have attracted an increasing attention due to their distinct properties including ultrahigh strength, high elastic strain limit, relatively low Young's modulus (50-100 GPa) and easy forming ability in viscous state. In addition, Zr-based BMGs displayed a superior corrosion resistance in artificial body fluids and a satisfactory biocompatibility. The combination of these unique properties makes them extremely promising for biomedical applications. The most promising applications for the BMGs are in dentistry and orthopaedics due to their mechanical superiority, where friction and wear properties are clinically important for the performance of the implants in the body. In the present study, a Ni-free BMC plate of Zr60Cu19Fe5Al10Ti6 with dimensions of 70 mmx12 mmx1.5 mm was successfully prepared by water-cooled copper mold casting. The friction and wear characteristics of the BMG under sliding in dry air, distilled water and phosphate buffered saline (PBS) have been investigated on a SRV friction and wear tester in a ball-on-plate contact configuration where the upper ball in motion was made of zirconia with 10 mm diameter and the lower stationary plate was made of the BMG. Ti6Al4V alloy was also tested under the same condition for comparison. The wear depth was investigated by a surface profiler and the wear volume was also calculated. The surface morphologies and the component of wear debris were examined by SEM and EDS. Compared with the Ti alloy, the BMG exhibits much less volume loss in the PBS solution, demonstrating that the BMG has a better wear resistance than the Ti alloy, though the former has a larger friction coefficient. The wear mechanism of the BMG is dominated by the corrosion wear with oxidation of the surface and fatigue flake mechanism.