Formation of a carbonaceous film on the surface of Cu in a bovine serum albumin solution

The tribochemical reaction between metal ions and proteins can result in the formation of a carbonaceous tribo-layer on the surface of metal-on-metal (MOM) artificial joints. This carbonaceous film can lubricate the tribo-pair and reduce the corrosion of the metal. The purpose of this work is to investigate the catalysis efficiency of Cu and Co ions in the formation of carbonaceous films at the contact regions. A ball-on-disc (Al2O3-on-Cu and Al2O3-on-Co alloy) friction mode in bovine serum albumin (BSA) solution was chosen for the wear test experiments. After the wear test, the tribo-layer formed on the wear spot (on Al2O3 ball) and wear track (metal disc) were collected and characterized. The results show that the Cu ions released upon friction promoted the adsorption of BSA on the wear track of Cu to give a protein film which was further transformed into a carbonaceous tribo-layer under the shear force between the Al2O3-Cu tribo-pair. When the Al2O3 ball and Co alloy were chosen as the tribo-pair, however, a carbonaceous tribo-layer was not observed on the Co alloy after the wear testing. This means that the catalysis efficiency of the Cu ion for the formation of a carbonaceous tribo-layer is stronger than that of the Co ion. [Display omitted] •The wear resistance of Cu is better than that of Co alloy in BSA solution.•The releasing of Cu ions can promote the formation of the ‘protein-layer’.•The ‘protein-layer’ would transform to be carbonaceous film on the wear track Cu.•The catalysis efficiency of Cu for the formation of carbonaceous film is stronger than that of the Co.