| 1. |
- Alberdi, Alberto, et al.
(författare)
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Tribological behavior of nanocomposite coatings based on fullerene-like structures
- 2011
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Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 85:12, s. 1087-1092
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new group of nanocomposite coatings based on integrating inorganic fullerene-like material (IFLM) structures into conventional coating matrices. Such coatings have been developed within the scope of the European funded FOREMOST project (FP6-NMP3-CT-2005-515840). Regarding the synthesis of these nanocomposite coatings based on fullerene-like components, two alternative routes were explored: introducing preformed IFLMs into the coating deposition process or forming the fullerene-like components in situ during the coating deposition process. Both methods have been demonstrated to be technically feasible, depending on the nature of the coating matrix or the desired fullerene-like structure. These new materials allow some independent control of tribological properties usually known as antagonists (very high load bearing capacity with a very low friction coefficient). In the case of unidirectional movement, under dry conditions, the best coatings developed in FOREMOST displayed a coefficient of friction in air within the range 0.04-0.10, depending on the degree of humidity and the test conditions. Pure sliding laboratory tests indicate that for some industrial applications fullerene-like nanocomposite coatings can give significant reductions in wear and friction coefficient when compared to similar coatings without fullerene-like components. The lubrication mechanisms through which these fullerene-like structures improve friction and prevent wear are also discussed in this paper.
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| 2. |
- Skjöldebrand, Charlotte, et al.
(författare)
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Current status and future potential of wear-resistant coatings and articulating surfaces for hip and knee implants
- 2022
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Ingår i: Materials Today Bio. - : Elsevier. - 2590-0064. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Hip and Knee joint replacements are a common and largely successful procedure that utilise implants to restore mobility and relieve pain for patients suffering from e.g. osteoarthritis. However, ions released from both the bearing surfaces and non-articulating interfaces, as in modular components, can cause hypersensitivity and local tissue necrosis, while particles originating from a polymer component have been associated with aseptic loosening and osteolysis. Implant coatings have the potential to improve surface properties compared to both bulk metal and ceramic alternatives. A ceramic coating has the potential to increase scratch resistance, provide greater wettability and reduce wear rates of the counter surface compared to the metallic substrate, whilst maintaining an overall toughness of the bulk implant material and hence lower the risk of catastrophic failure of the device compared to a bulk ceramic material. Coatings can also act as barriers to inhibit ion release from the underlying material caused by corrosion. This review aims to provide a comprehensive overview of coatings that are (i) in current clinical use and (ii) under investigation for future use in joint replacements. While the majority of coatings belong predominantly in the latter group, a few coated implants have been successfully exploited and are available for clinical use in specific applications. Commercially available products include titanium nitride (TiN), titanium niobium nitride (TiNbN), oxidized zirconium (OxZr) and zirconium nitride (ZrN) based coatings, whereas current research is focused not only on these, but also on diamond-like-carbon (DLC), silicon nitride (SiN), chromium nitride (CrN) and tantalum-based coatings (TaN and TaO). The coating materials referred to above that are still at the research stage have been shown to be non-cytotoxic and to reduce wear in a laboratory setting. However, the adhesion of the coatings to the implant remains a main area of concern, as poor adhesion can cause delamination and excessive wear. In clinical applications zirconium implant surfaces treated to achieve a zirconium oxide film and TiNbN coated implants have however been proven comparable to traditional cobalt chromium implants with regards to revision numbers. In addition, the chromium ion levels measured in the plasma of patients were lower and allergy symptoms were relieved. Therefore, coated implants could be considered an alternative, in particular, for patients with metal hypersensitivity. There have also been unsuccessful introductions to the market, such as DLC coated implants, and therefore this review also attempts to summarize the lessons learnt.
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