Reduced tribocorrosion of CoCr alloys in simulated body fluid after nitrogen insertion

Lutz, J.; Mändl, S.

doi:10.1016/j.surfcoat.2010.01.048

Cited by 34 publications

(29 citation statements)

References 18 publications

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“…While the cathodic domain is similar to the untreated alloy, the anodic domain is characterized by much higher current densities suggesting absence of passivity. Apparently the loss of passivity is a consequence of the formation of the c N phase rather than the depletion in Cr due to nitrides formation as usually indicated in literature [8]. Indeed, PPN-I and PPN-II behave similarly although chromium nitrides form predominantly in PPN-II as confirmed by the XRD results.…”

Section: Polarization Behavioursupporting

confidence: 80%

“…Interestingly, while nitriding clearly reduces wear in dry conditions, its effect in NaCl is less pronounced. This phenomenon was already observed in previous studies on nitrided CoCrMo [8] and on nitrided NiCr [18] and was related to the different wear mechanisms acting on each material depending on the environment.…”

Section: Dry Testssupporting

confidence: 78%

“…These studies highlighted the importance of process temperature on the formation of different surface structures on CoCrMo: a hard chromium nitride layer is formed at temperatures above 500°C, while at temperatures below 500°C, nitrogen diffuses in the alloy to form a new structure, the so-called c N phase, which is a nitrogensupersaturated fcc structure [7]. The tribocorrosion performance of a plasma-nitrided biomedical CoCrMo alloy at different temperatures has been only studied by Lutz et al [8] in simulated body fluids. Those authors observed that while nitriding effectively reduces wear in dry conditions, it has a less pronounced or no effect in simulated body fluids depending on process temperature.…”

Section: Introductionmentioning

confidence: 99%

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Tribocorrosion of Pulsed Plasma-Nitrided CoCrMo Implant Alloy

2012

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In the present study, a forged CoCrMo (ISO 5832-12) has been subjected to pulsed plasma treatment in a N 2 /H 2 atmosphere at low temperatures (below 500°C). This treatment resulted in the formation of a layer composed by dispersed chromium nitride particles in a N-enriched metal matrix. The materials were tested for corrosion and tribocorrosion performance in 0.9 wt% NaCl at room temperature under controlled electrochemical conditions. After the treatment, the alloy loses its passive nature. The electrode potential was found to critically affect the corrosion and the tribocorrosion rates. In the nitrided alloy, a significant increase of corrosion rate was found at high potentials, while tribocorrosion was determined mainly by mechanical wear and not affected by potential. On the other hand, the untreated CoCrMo alloy exhibited stable corrosion over a wide range of potentials. Its tribocorrosion rate was similar to the nitrided alloy samples at low potentials, but it increased dramatically at high potentials where passivity triggered severe wearaccelerated corrosion and promoted mechanical wear. The present study shows that the electrochemical conditions determine material deterioration and should therefore be considered when selecting materials for tribocorrosion applications such as biomedical implants.

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Section: Polarization Behavioursupporting

confidence: 80%

Section: Dry Testssupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

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Tribocorrosion of Pulsed Plasma-Nitrided CoCrMo Implant Alloy

2012

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“…However, a selective increase in the cobalt ion release rate, while no significant change in nickel or chromium release was obtained even for samples showing nitrogen in solid solution [31]. In contrast, a threshold for the onset of an increased corrosion current corresponding to the formation of CrN precipitates is observed for nitrogen implantation into austenitic stainless steel [32].…”

Section: Introductionmentioning

confidence: 87%

“…For biomedical applications, the PIII treatments presented here lead to a significant reduced wear rate and correspondingly lower particle generation [31], while the corrosion rate and ion release is increased with the absolute changes themselves depending on the process temperature for PIII nitriding. At lower processing temperatures of 350 °C and below, an increase in the corrosion rate by a factor of up to 5 is observed.…”

Section: Release Of Ions and Implications For Biomaterialsmentioning

confidence: 98%

Corrosion behaviour of medical CoCr alloy after nitrogen plasma immersion ion implantation

Lutz

Dı́az

Garcı́a

et al. 2011

Surface and Coatings Technology

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Surface treatment of medical CoCr alloys L605 by nitrogen plasma immersion ion implantation (PIII) leads to the formation of a hard and wear resistant surface layer, consisting of nitrogen in solid solution. However, a detailed investigation of the corrosion properties by potentiodynamic polarization and electrochemical impedance spectroscopy shows that even at processing temperatures of 350 °C, where no CrN precipitates are observed, no complete passivation of the surface by formation of a protective Cr 2 O 3 layer is possible leading to enhanced corrosion rates further increasing with increasing PIII processing temperature. It is postulated that the enhanced affinity of chromium for nitrogen leads to a reduced mobility inside the alloy, thus prohibiting a timely surface passivation. Nevertheless, a surface modification where a moderate decrease in corrosion resistance coupled with a significant reduction in generated wear particles should be feasible for biomedical applications.

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Cytocompatibility of nitrogen plasma ion immersed medical cobalt–chromium alloys

Schröck

Schneider

Lutz

et al. 2013

J Biomedical Materials Res

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Wear particles and ion release from medical CoCr contribute to the risk for aseptic loosening. Nitrogen plasma immersion ion implantation (PIII) has been shown to reduce wear of CoCr but is associated with increased Co ion release. This work investigated the cytocompatibility of CoCr modified by nitrogen PIII at different temperatures (mCoCr). The osteosarcoma cell line Saos-2, mesenchymal stem cells (MSCs), and mononuclear cells (MNCs) were grown directly on CoCr/mCoCr discs or treated with CoCl2. Proliferation and metabolic activity of Saos-2 and MSC were decreased on mCoCr in correlation with increasing implantation temperature. The elevated Co ion release seemed to play a decisive role since analog effects were observed by treatment of cells with CoCl2. Proliferation of phytohemagglutinin-stimulated MNC was reduced in the presence of CoCr discs or CoCl2. For MNC-alloy cultures we observed an increase in interleukin 2 (IL-2) and a decrease in interferon γ (IFN-γ) and IL-10 secretion compared to cultures without alloys. The results of this study demonstrate that PIII process temperature and corresponding Co ion release correlate with material cytocompatibility. Therefore, the two competing parameters, reduction of wear and increase in Co ions, have to be taken into consideration for the evaluation of the clinical applicability of nitrogen-implanted CoCr.

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Reduced tribocorrosion of CoCr alloys in simulated body fluid after nitrogen insertion

Cited by 34 publications

References 18 publications

Tribocorrosion of Pulsed Plasma-Nitrided CoCrMo Implant Alloy

Tribocorrosion of Pulsed Plasma-Nitrided CoCrMo Implant Alloy

Corrosion behaviour of medical CoCr alloy after nitrogen plasma immersion ion implantation

Cytocompatibility of nitrogen plasma ion immersed medical cobalt–chromium alloys

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