Electroexplosive hafnium coating on titanium implant modified by nitrogen ions and electron beam processing

Abstract

In the present research a novel method of increasing in mechanical characteristics (wear resistance, friction coefficient, Young's modulus and nanohardness) of titanium implants is proposed. A complex processing was used including electroexplosion spraying of hafnium coating and subsequent electron-beam processing combined with nitriding. Electroexplosion spraying was carried out in the modes ensuring the formation of microrelief on the boundary with titanium substrate. Electron beam processing of hafnium coating surface allowed its smooth surface to be provided and the coating to be nanostructurized. Smooth surface makes the coating a more commercially profitable for selling the medical products and nanostructurization ensures a high level of mechanical and biolodical properties. The obtained coating of Ti-Hf-N system contributes to the increase in wear resistance by the factor of 17.4 and simultaneous increase in friction coefficient by 7%. The coating also ensures the increase in nanohardness by the factor of 2.05 and the increase in the Young modulus by 13% in comparison with Ti-6Al-4V alloy. Nitriding allowed the strengthening of hafnium coating by nitrides. In the coating 40–50 μm in thickness hafnium is distributed homogeneously and is presented in the phases of HfN, Hf and HfTiN2. The comparison of the phases being formed in the coating and the structural components of coatings' surface depending on processing mode is made. After combined processing the surface of the coating is presented by three different structural components. The proliferative activity of fibroblasts and antimicrobial activity were studied as biological properties of the coating in the present research. The structure of the coating is studied by the methods of modern physical materials science. The complex analysis carried out enables one to recommend the coating for subsequent tests on experimental animals (rabbits) and further commercial production of strengthened titanium implants. To study osteointegration the samples of the experimental implants with bioinert coatings obtained in the present research are to be introduced into rabbits' osseous tissue in future.