Tribological behavior of a Ni-free Zr-based bulk metallic glass with potential for biomedical applications.

In this study, the tribological behavior of a Ni-free Zr53Al16Co23·25Ag7.75 bulk metallic glass (BMG) was investigated in dry-sliding and simulated physiological media using ball-on-disk reciprocating friction. The effects of sliding load, speed, media and counterpart materials on the wear resistance of the Zr-Al-Co-Ag BMG were illustrated. Under dry-sliding in air, wear resistance of the Zr-based BMG decreases with increasing sliding load, and wear deterioration is controlled by oxidation and abrasive wear. With increasing sliding velocity, larger plastic deformation occurs on the surface of BMG due to the frictional heat. The BMG exhibits decreased wear resistance in 0.9% NaCl and phosphate buffer saline (PBS) solutions in comparison with that in air and deionized water, which is probably associated with tribocorrosion controlled by synergistic effects of abrasive and corrosive wear. The wear resistance of the Zr-based BMG against Si3N4 counterpart material is inferior to that against ZrO2, whereas the case is contrary to that against Al2O3. The effect of ceramic counterpart materials on the wear resistance of BMG is discussed based on their Young's modulus and fracture toughness.