TRIBOLOGICAL STUDY OF MAGNESIUM ALLOYS FOR IMPLANT APPLICATIONS

Magnesium and its alloys have been found to potential candidates for biodegradable implant applications. However, magnesium and its alloys are broadly known to have poor tribological properties, but detailed specifics on wear performance are scarce. This research investigates the tribological characteristics on Mg-Zn-Ca-RE alloys and pure magnesium under as-cast and extruded conditions. Pure magnesium and Mg-Zn-Ca-RE alloys were hot extruded at 350 degrees C and 400 degrees C. Magnesium and Mg-Zn-Ca-Re alloy were also cast at 350 degrees C and heat treated at 510 degrees C. Directional wear properties were investigated using a CETR-UMT 2 microtribometer under unlubricated conditions in a reciprocating configuration for 120 cycles, with normal loads ranging from 0.5N-2.5N. Wear tests were conducted in directions: cross-sectional, longitudinal (along the extrusion direction) and transverse direction (perpendicular to the extrusion direction). Wear properties and friction properties were analyzed using a microtribometer, a mechanical stylus profiler, and microindentation. Surface morphology and microstructure were characterized using optical microscopy, scanning electron microscopy, and optical profilometry. The results show a lower wear rate in the transverse and cross-sectional direction compared to the longitudinal direction.