There are important differences among the metal alloys used for metal-on-metal bearings. (Fig. 1) Zimmer is the only manufacturer using a high-carbon, wrought-forged cobalt-chromium alloy (CoCr) for all metal-on-metal bearings.

  • The high-carbon, wrought-forged Co-Cr alloy used for Metasul Material has a higher hardness.
  • Several in vitro wear studies show a significant difference in wear between high-carbon alloys (0.20% - 0.25% carbon concentration) and low-carbon alloys (0.05% - 0.08% carbon concentration). (Fig. 2)
  • A recent independent study demonstrates a clear trend that components manufactured from wrought Co-Cr have a lower surface roughness than those manufactured from cast Co-Cr.5  This is because Metasul Material contains finer carbides with a more homogenous carbide distribution. (Fig. 3)
  • Lower roughness has been shown to facilitate the creation of a thicker lubrication film,7 providing more efficient lubrication and contributing to wear reduction.

References

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  6. Data on file at Zimmer, Inc.
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