The response of ASTM F1537 Co-28Cr-6Mo alloy with different phase constituents to low-temperature plasma carburising

摘要

Co-Cr alloys are the most widely used metallic biomaterials for metal-on-metal joint prostheses. However, concerns about increased revision rate associated with metal-on-metal replacements have been raised recently. This research was aimed at studying the response of medical grade ASTM Fl537 Co-28Cr-6Mo alloy with different phase constituents to low-temperature plasma carburising (LTPC) to address the tribocorrosion problems of the current metal-on-metal joint prostheses.ududTo this end, n series of heat treatments were designed to produce samples with an a-FCC dominated (>95%), an c-HCP dominated (>97%) and a dual phased (40% c-HCP) microstructures. An optimised low-temperature plasma carburising (LTPC) treatment wns applied to the heat-treated samples. The microstructure of the plasma carburised surface layers were characterised by XRD, GDS, SEMIEDX and TEM, and the properties of the surface carburised layers were evaluated using micro- a•nd nano-indentation, reciprocating wear and electrochemical corrosion tests, and tribocorrosion tests a t different electrochemical potentials.ududThe experimental results have showed that the response of the Co-28Cr-6Mo alloy to the LTPC treatment is highly dependent on the phase constituent. The LTPC treatment can significantly increase the hardness, load bearing capacity and dry wear resistance and tribocorrosion properties of all the Co-28Cr-6Mo samples with different phase constituents.ud