The effect of N, C, Cr, and Nb content on silicon nitride coatings for joint applications [Elektronisk resurs]

• Ceramic coatings are an alternative to achieve or maintain a high wear resistance of metallic surfaces, and simultaneously allow for a reduction in metal ion release. Silicon nitride based (SiN x ) coatings deposited by high power impulse magnetron sputtering (HiPIMS) have shown potential for use in joint implants seen from an improved chemical stability in combination with a good adhesion. The aim of this study was to investigate the effect of N, C, Cr and Nb content on the tribocorrosive performance of 3.7 to 8.8 µm thick SiN x coatings deposited by HiPIMS onto CoCrMo discs to improve  the mechanical properties and/or chemical stability of SiN x . Coating composition was evaluated by X-ray photoelectron spectroscopy (XPS) and the surface roughness by Vertical Scanning Interferometry (VSI). Hardness and Young’s modulus were investigated by nanoindentation and coating adhesion was measured by scratch tests. Multidirectional wear tests against UHMWPE pins were performed for 2 million cycles in bovine serum solution (25%) at 37°C, at an estimated contact pressure of 2.1 MPa. Coatings with a relatively low hardness tended to fail earlier in the wear test, due to chemical reactions and eventually dissolution, accelerated by the tribological contact. In fact, while no definite correlation could be observed between coating composition (N: 42.6-55.5 at%, C: 0-25.7 at%, Cr: 0 or 12.8 at%, and Nb: 0-24.5 at%) and wear performance, it was apparent that high-purity and/or -density coatings (i.e. low oxygen content and high nitrogen content) were desirable to prevent coating and/or counter surface wear. Coatings deposited with a higher energy fulfilled the target profile in terms of low surface roughness (R a <20nm), adequate adhesion (Lc2>30N), chemical stability over time in the tribocorrosive environment, as well as low polymer wear, presenting potential for a future application in joint bearings. 

Ämnesord

Engineering and Technology  (hsv)

Medical Engineering  (hsv)

Medical Materials  (hsv)

Teknik och teknologier  (hsv)

Medicinteknik  (hsv)

Medicinska material och protesteknik  (hsv)

Teknisk fysik med inriktning mot materialvetenskap  (uu)

Engineering Science with specialization in Materials Science  (uu)

Genre

government publication  (marcgt)

Indexterm och SAB-rubrik

silicon nitride

coating

joint replacement

wear

adhesion