The composition of tribofilms produced on metal-on-metal hip bearings

Abstract

Following wear testing in a hip simulator, the bearing surfaces of 36 mm metal on metal total hip replacements showed the formation of tribochemical layers. These layers were investigated in a transmission electron microscope, and analysis was performed using electron energy loss spectroscopy, energy dispersive x-rays and selected area electron diffraction. The tribofilm formed at the edge of the wear scar was 100 s of nanometres thick and contained cobalt sulphide particles embedded within. The film itself was rich in carbon, and appeared to contain no long range graphitic ordering when analysed with electron energy loss spectroscopy, and the spectra gathered from the tribofilm closely resembled those collected from amorphous carbon. The location at which the most substantial tribological layers formed may be explained by the formation of a blunt wedge at the edge of the wear scar following conformal changes to the bearing surfaces.

The effect of contact load on CoCrMo wear and the formation and retention of tribofilms

“…Here, we speculate and provide evidence that this could be related to the presence or absence of tribofilms. A ‘tribofilm’ is a carbonaceous layer or film (‘tribofilm’) that forms on the surfaces of MoM components [13–17]. We have recently reported that the film contains graphitic material [18], although this has yet to be independently confirmed [17].…”

Surface and subsurface changes as a result of tribocorrosion at the stem-neck interface of bi-modular prosthesis

“…These have been associated with an increase in interfacial hardness and the origin of nano-scale debris typically associated with Metal-on-Metal bearings [33,34]. Furthermore the changes in subsurface microstructure and tribo-chemical processes (chemical reactions owing to the tribological interactions) have been hypothesised to contribute to the overall degradation of sliding interfaces [35][36][37]. Zeng et al [32] has recently demonstrated decreases in wear depending upon the initial interfacial crystallinity.…”

Uneven damage on head and liner contact surfaces of a retrieved Co–Cr-based metal-on-metal hip joint bearing: An important reason for the high failure rate

“…Instead, it suggests that metal-organic composite-like layers are formed during the use of MoM bearings as a result of a tribochemical reaction. Recently, graphitic [25] and nongraphitic [41] carbon-rich tribological layers have been reported in studies of retrieved MoM bearings and MoM bearings subjected to hip simulators. In the present study, XPS analysis was performed to examine the chemistry of the nanocrystalline subsurface structure of the retrieved head.…”