Surface modification of ASTM F-1537 Co-Cr alloy by low temperature plasma surface alloying

Liu, Ran (2013). Surface modification of ASTM F-1537 Co-Cr alloy by low temperature plasma surface alloying. University of Birmingham. M.Res.

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Abstract

Cobalt-chromium (Co-Cr) alloys are one of the most suitable metallic biomaterials especially for high load body implants. However, recently, there are concerns over the wear of metal-on- metal artificial hip joints made from Co-Cr alloys due to the formation of numerical nano- sized wear debris from the articulating surfaces.

In this work, medical grade ASTM F-1537 Co-Cr alloy has been plasma nitrided (PN) and carbonitrided (PCN) at 300-400°C for 10-30 h. The microstructure and the mechanical, chemical and tribological properties of the modified surfaces were fully characterised.

The results demonstrate that a carbon S-phase layer and a dual S-phase case can be generated by PN and PCN respectively. The hardness and unlubricated wear resistance against a WC ball can be increased respectively by more than 100% and two orders of magnitude by the low temperature plasma treatments. The corrosion resistance of the low-temperature (≤350\(^0\)C) plasma surface nitrided Co-Cr alloy is similar to the untreated material and the plasma carbonitrided samples possess better corrosion behaviour than the plasma nitrided samples. Corrosion-wear resistance in Ringer’s solution can be increased by 5-10 times by some of the plasma treatments.

Type of Work:

Thesis (Masters by Research > M.Res.)

Award Type:

Masters by Research > M.Res.

Supervisor(s):