Effects of carbon addition on wear mechanisms of CoCrMo metal-on-metal hip joint bearings

Yan Chen, Yunping Li, Yuichiro Koizumi, Hani Haider, Akihiko Chiba

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


The wear behaviors of biomedical CoCrMo prosthetic alloys containing various amounts of carbon were investigated using a standard hip joint simulator in a simulated body fluid. A few chunks and punctate σ-phase precipitates were observed in the low-carbon (LC) alloy; these were responsible for the abrasion and run-in wear. Increasing the carbon content led to greater precipitation of globular M23C6-type carbides. As a result, lower wear loss was observed in the high-carbon (HC) alloy. However, the Student's t-test analysis on wear loss indicated that there was no significant difference in wear loss between the LC-LC and HC-HC combinations. Surface fatigue caused by torn-off of Mo-rich carbides was the dominant wear mechanism in the HC alloy. Further, Cr-rich carbides prevent three-body abrasion and increase the wear resistance.

Original languageEnglish (US)
Pages (from-to)997-1004
Number of pages8
JournalMaterials Science and Engineering C
StatePublished - Jul 1 2017


  • Carbon addition
  • CoCrMo alloy
  • Mo-rich-carbide-induced-pitting
  • Wear mechanism

ASJC Scopus subject areas

  • Bioengineering
  • Biomaterials


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