Dry and lubricated tribological behavior of a Ni- and Cu-free Zr-based bulk metallic glass

Abstract In this study, tribological behavior of a Zr₅₃Al₁₆Co_23.25Ag_7.75 bulk metallic glass (BMG) in air and phosphate buffer saline (PBS) solution was investigated and compared with biomedical alloy Ti-6Al-4V. It is found that wear resistance of the Zr-Al-Co-Ag BMG sliding in air is superior to that of Ti-6Al-4V alloy. Under dry friction condition, wear deterioration of Zr-based BMG is controlled by oxidation and adhesive wear whereas Ti-6Al-4V alloy is jointly dominated by abrasive and adhesive wear. However, Zr-based BMG presents decreased wear resistance under lubricated friction condition in comparison with dry friction condition. In contrast, Ti-6Al-4V alloy shows improved wear resistance sliding in PBS. This is probably associated with the inferior pitting corrosion resistance of Zr-Al-Co-Ag BMG in the medium containing chloride ions, which may cause tribocorrosion controlled by synergistic effects of abrasive and corrosive wear. The possible mechanism for corrosion accelerating wear is discussed based on the tribological behavior of this Zr-based BMG.