Wear Behavior of Biodegradable Mg–5Zn–1Y–(0–1)Ca Magnesium Alloy in Simulated Body Fluid

In this study, wear behavior of biodegradable Mg–5Zn–1Y–(0–1)Ca alloys is investigated in simulated body fluid. Wear test is performed using a pin-on-disc system, under three different loads of 10, 20 and 40 N, at ambient temperature; and the whole configuration is exposed to simulated body fluid. The volumetric wear rate and friction coefficient of each alloy are determined. The worn surfaces are analyzed using a scanning electron microscope, equipped with an energy dispersive spectrometer to determine the involved main wear mechanism. The Ca-free alloy contains α-Mg and intermetallic Mg₃YZn₆, and Ca addition produces another intermetallic Ca₂Mg₆Zn₃. Results show that different wear mechanisms and rates, as well as friction coefficients, are achieved due to the effect of simulated body fluid on the alloys with regards to the different Ca content and the presence of corrosion products. Microscopic studies reveal that abrasion is the dominant wear mechanism taken place in all alloys under all loads. Increasing Ca content leads to wear resistance deterioration while increasing wear load results in decreasing wear rate and friction coefficient of the alloys. The results of the wear rate and friction coefficient of Mg–5Zn–1Y–1Ca alloy exhibit greater instability compared to the other alloys due to its more enhanced corrosion caused by the formation of the intermetallic Ca₂Mg₆Zn₃ particles. In total, Ca-free alloy provides the best wear resistance, especially at the higher wear load.