Abstract
This paper presents experimental evidence that thin (< ∼ 200 nm) boron coatings, deposited with a (vacuum) cathodic arc technique on pre-polished Co-Cr-Mo surfaces, could potentially extend the life of metal-on-polymer orthopedic devices using cast Co-Cr-Mo alloy for the metal component. The primary tribological test used a linear, reciprocating pin-on-disc arrangement, with pins made of ultra-high molecular weight polyethylene. The disks were cast Co-Cr-Mo samples that were metallographically polished and then coated with boron at a substrate bias of 500 V and at about 100 °C. The wear tests were carried out in a saline solution to simulate the biological environment. The improvements were manifested by the absence of a detectable wear track scar on the coated metal component, while significant polymer transfer film was detected on the uncoated (control) samples tested under the same conditions. The polymer transfer track was characterized with both profilometry and Rutherford backscattering spectroscopy. Mechanical characterization of the thin films included nano-indentation, as well as additional pin-on-disk tests with a steel ball to demonstrate adhesion, using ultra-high frequency acoustic microscopy to probe for any void occurrence at the coating-substrate interface.
Original language | English |
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Pages (from-to) | 3070-3080 |
Number of pages | 11 |
Journal | Thin Solid Films |
Volume | 516 |
Issue number | 10 |
DOIs | |
State | Published - Mar 31 2008 |
Funding
This research was supported by NIH/NIAMS, Grant Number 1 R43 AR051262-01 (Phase I SBIR) to HY-Tech Research Corporation and by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of FreedomCAR and Vehicle Technologies, as part of the High Temperature Materials Laboratory User Program at the Oak Ridge National Laboratory (ORNL), managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract number DE-AC05-00OR22725. The mechanical and wear studies were carried out at ORNL under this latter program. The RBS analyses were carried out at Alabama A&M University's Research Institute (AAMURI™); the contributions of AAMURI's Dr. Claudiu Muntele in assisting with both the RBS setup and the handling of the data are gratefully acknowledged. The HY-Tech authors would like to thank Dr. E.J. Yadlowsky for continued support, advice and encouragement.
Keywords
- Amorphous materials
- Biomaterials
- Boron
- Coatings
- Cobalt alloy
- Deposition process
- Rutherford backscattering spectroscopy
- Tribology