Tribological Performance and Anticorrosion Stability of Co-Cr-Mo Alloy with Thermal Oxidation Layer under Bovine Serum Albumin Solution

ABSTRACT

Co-Cr-Mo alloy used for an artificial hip joint prosthesis was treated in a vacuum tubular furnace to obtain a thermal oxidation layer with anticipated surface properties. The tribological performance of the thermal oxidation layer was subsequently characterized under bovine serum albumin (BSA) lubrication by suitable accelerating wear with a pin-on-plate tribometer. The influence of (1) BSA concentration in range of 2–20 mg/ml and (2) load in the range of 2–10 N on wear was analyzed. Stability of the oxidation layer was also studied by electrochemical testing to analyze its corrosion resistance. The change in microstructure of the substrate, after removal of the oxidation layer, was also evaluated. Results should that (1) the coefficient of friction (COF) under the applied load of 10 N fluctuated by about 0.15, (2) a higher value of wear loss 4.23 × 10⁻⁴ mm³ in 20 mg/ml BSA, and (3) a decrease in the COF and increase in wear loss under a load of 2 to 8 N. It was suggested that the corrosion potential of the oxidation layer of −0.25 V in BSA solution and −0.13 V in NaCl solution moves further toward positive values and the corrosion current density is reduced, implying that the specimens with a thermal oxidation layer gave better corrosion resistance than the controlled Co-Cr-Mo alloy specimen.

KEYWORDS:

• Thermal oxidation layer
• tribology
• electrochemical stability
• BSA

Funding

This research was financially supported by the National Natural Science Foundation of China (Grant No. 51175406).