Investigation of the role of tribofilms in self-mating CoCrMo systems utilizing a quartz crystal microtribometer

• A tribofilm-like material has been generated electrochemically.
• The QCM is incorporated into a wear test.
• Sputtered CoCrMo film is representative of the bulk alloy subsurface.
• Protein within the testing fluid reduces friction.
• Tribofilm-like material reduces friction.

A new experimental device has been developed to investigate the properties of tribofilms as they occur in hip implants made from CoCrMo alloys. The device has the ability to detect small mass changes on the alloy surface and consists of CoCrMo alloy pins articulating against a quartz crystal that is sputter coated with the same CoCrMo alloy. The instrument not only measures normal and friction forces, but the quartz substrate also enables the in situ quantification of mass changes due to wear or tribofilm formation with a quartz crystal microbalance (QCM). The functionality of the test rig is demonstrated in a pilot study with different testing fluids, and methods to pre-condition surfaces with a tribofilm-like material are described.