title: Development of superlattice CrN/NbN coatings for joint replacements deposited by high power impulse magnetron sputtering.
abstract: The demand for reliable coating on medical implants is ever growing. In this research, enhanced performance of medical implants was achieved by a CrN/NbN coating, utilising nanoscale multilayer/superlattice structure. The advantages of the novel high power impulse magnetron sputtering technology, namely, its unique highly ionised plasma, were exploited to deposit dense and strongly adherent coatings on CoCr implants. Transmission electron microscopy analysis revealed coating superlattice structure with bi-layer thickness of 3.5 nm. CrN/NbN deposited on CoCr samples showed exceptionally high adhesion, critical load values of LC2 = 50 N in scratch adhesion tests. Nanoindentation tests showed high hardness of 34 GPa and Young's modulus of 447 GPa. Low coefficient of friction (μ) 0.49 and coating wear coefficient (K C) = 4.94 × 10(-16) m(3) N(-1) m(-1) were recorded in dry sliding tests. Metal ion release studies showed a reduction in Co, Cr and Mo release at physiological and elevated temperatures (70 °C) to almost undetectable levels (<1 ppb). Rotating beam fatigue testing showed a significant increase in fatigue strength from 349 ± 59 MPa (uncoated) to 539 ± 59 MPa (coated). In vitro biological testing has been performed in order to assess the safety of the coating in biological environment; cytotoxicity, genotoxicity and sensitisation testing have been performed, all showing no adverse effects.
authors: Sheffield Hallam University, City Campus, Howard Street, Sheffield, UK.
authors: Papken Ehiasarian
authors: PE
authors: Hovsepian
authors: Sheffield Hallam University, City Campus, Howard Street, Sheffield, UK.
authors: Arutiun Papken
authors: AP
authors: Ehiasarian
authors: Sheffield Hallam University, City Campus, Howard Street, Sheffield, UK.
authors: Yashodhan
authors: Y
authors: Purandare
authors: Sheffield Hallam University, City Campus, Howard Street, Sheffield, UK. A.Arunachalamsugumaran@shu.ac.uk.
authors: Arunprabhu Arunachalam
authors: http://orcid.org/0000-0002-5087-4297
authors: AA
authors: Sugumaran
authors: Zimmer Biomet UK Limited, Dorcan Industrial Estate, Murdoch Road, Swindon, UK.
authors: Tim
authors: T
authors: Marriott
authors: Zimmer Biomet UK Limited, Dorcan Industrial Estate, Murdoch Road, Swindon, UK.
authors: Imran
authors: I
authors: Khan
mesh_terms: D000497:Alloys; D019643:Arthroplasty, Replacement / Q000295:instrumentation*; D002448:Cell Adhesion; D002857:Chromium / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003343:Corrosion; D017276:Friction; D006244:Hardness; D006801:Humans; D007477:Ions; D008422:Materials Testing; D008670:Metals; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D009556:Niobium / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*; D009985:Orthopedics / Q000379:methods; D011312:Pressure; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D000497:Alloys; D020099:Coated Materials, Biocompatible; D007477:Ions; D008670:Metals; D009556:Niobium; D002857:Chromium; D009584:Nitrogen