Subsurface characterisation of wear on mechanically polished and electro-polished biomedical grade CoCrMo

In-situ generated tribomaterial in metal/metal contacts: Current understanding and future implications for implants

“…Thus, in the beginning, both contacting surfaces undergo a process of adjustment by either wear and/or plastic deformation before the contacting bodies interact predominantly elastic [31, 38–40]. Importantly, at such small wear rates, the elastic interaction is of cyclic nature during steady-state and, therefore, might allow for cyclic-plastic deformation (cyclic-creep or ratcheting) [41–43] followed by mechanical instabilities like shear bands [44–48] as well as crack initiation and propagation [49–51]. Finally the microstructure of standardized HC-CoCrMo alloys might vary markedly depending on the production route and sequence [52], with still unknown relations to the actual wear or corrosion behavior.…”

“…In-vitro studies [86, 87, 89, 94, 48] consistently report the build-up of carbonaceous layers while in-vivo results mention a variety of surface films ranging from thick oxide films to organic or even graphitic layers [9, 92]. This is not surprising since in-vitro studies are executed in a well-defined environment (e.g.…”

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

“…The importance of subsurface and interfacial microstructure has been well documented in the orthopaedic sector [29,30]. Many authors have presented evidence of dynamic recrystallization [31], strain-induced transformation and the formation of nano-crystalline material of CoCrMo articulating surfaces in both retrieval and experimental studies [32]. However these have mainly been concerned with reciprocating hard-on-hard surfaces of which are now almost obsolete.…”

“…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. Whilst the evolution mechanisms for microstructural changes appear to be strain dependant and similar regardless of the initial crystallinity, clinical findings do not correlate in the case for fretting contacts.…”

Electron Microscopy and Spectroscopy in the Analysis of Friction and Wear Mechanisms

“…Typical implant materials include CrCrMo alloys and ceramics, as well as the applications of physical vapour deposition (PVD) hard coatings [31][32][33][34]. It has been found that the surface conditions, such as the applied mechanical and electrochemical polishing as well as the adhesion property of hard coatings, have strong influence on the service life performance [35,36]. The mechanisms of the associated friction and wear are related to the generation of lubricious tribofilms [37][38][39][40].…”