Fretting-corrosion of CoCr-alloys against TiAl6V4: The importance of molybdenum in oxidative biological environments

Periprosthetic fluids often contain reactive oxygen species, including H2O2, that are generated during inflammatory processes. Here, we investigated the fretting-corrosion behavior of CoCrX-alloys (X = Mo, Fe) in a complex protein-containing lubricant, with and without the addition of H2O2. Given th...

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Bibliographic Details
Published in:Wear 2021-07, Vol.477, p.203813, Article 203813
Main Authors: Wimmer, M.A., Radice, S., Janssen, D., Fischer, A.
Format: Article
Language:English
Subjects:
Alloying effects
Alloying elements
Alloys
Corrosion tests
Factorial experiments
Fretting
Fretting corrosion
Hydrogen peroxide
Intermetallic compounds
Iron
Knee/hip prosthesis
Line contact
Molybdenum
Open circuit voltage
Prostheses
Reactive oxygen species
Titanium base alloys
Tribocorrosion
Wear
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Summary:Periprosthetic fluids often contain reactive oxygen species, including H2O2, that are generated during inflammatory processes. Here, we investigated the fretting-corrosion behavior of CoCrX-alloys (X = Mo, Fe) in a complex protein-containing lubricant, with and without the addition of H2O2. Given the known protective role of molybdenum as an alloying element in metal degradation, we considered its effects by designing a two-way factorial experiment. The aim of the study was to investigate tribocorrosive mechanisms in modular joints of knee and hip prostheses. A previously described test-rig was used to run fretting corrosion tests of CoCrX-alloys with (X=Mo) and without (X=Fe) molybdenum against TiAl6V4 in bovine calf serum (BCS) with and without a physiological relevant H2O2 level (3 mM) in gross slip mode (4 Hz, ±50 μm, pmax=0.18 GPa, 37 °C, 50,000 cycles). Two CoCr-pins were pressed against a cylindrical TiAl6V4-rod, forming a line contact. Normal and frictional forces, the displacement, and the open circuit potential (OCP) were measured and recorded continuously. The dissipated frictional work was independent of alloy composition. The addition of H2O2 lowered the dissipated frictional work and increased wear, and this was significant in the absence of Mo. The mean OCP value was lower with Mo-containing than with Mo-free alloy in both pure BCS (p = .042), and BCS + H2O2 (p 
ISSN:0043-1648
1873-2577
DOI:10.1016/j.wear.2021.203813