Evaluation of microstructure, mechanical properties and osseointegration capacity of laser cladding β-type TiNbZr coatings

Biomedical titanium alloys exhibit limitations in their application within the medical field as a result of insufficient bioactivity, potential allergic reactions, and constrained mechanical properties. Surface modification is regarded as an effective method to enhance the interaction between implants and biological systems. In this study, beta-type TiNbZr alloy coatings with varying Zr content were successfully fabricated on Ti6Al4V (TC4) using laser cladding modification technology, with the objective of enhancing the mechanical interlocking between the matrix and bone tissue. The mechanical properties and biological activity of the coating were deeply investigated to assess its viability as an implant material. The results indicate that the surface of the matrix has been successfully coated with a metallurgically bonded layer, exhibiting an average thickness of 844.596 +/- 51.208 mu m. An increase in Zr content facilitated the transformation of the duplex alpha+beta structure into a beta-phase structure. The average hardness of the coating was 381.42 HV0.2, with the hardness of the duplex structure surpassing that of the single-phase structure; notably, the hardness value for 5 wt% Zr (406 HV0.2) was the highest. The corrosion current was reduced by two orders of magnitude, and primarily localized corrosion occurs, with microcracks and corrosion pits forming. The surface roughness exhibited an inverse relationship with the contact angle, and the surface hydrophilicity and micron-level roughness (0.726-0.945 mu m) were conducive to cell adhesion. Furthermore, the formation of the Ca/P phase during the biomineralization test substantiated that the coating exhibits biological activity conducive to promoting cell growth. This research offers novel perspectives for the design and optimization of beta-type TiNbxZr alloy coating materials with excellent corrosion resistance, higher hardness, and biological activity.