Optimization of anti-wear and anti-bacterial properties of beta TiNb alloy via controlling duty cycle in open-air laser nitriding

Abstract

A multifunctional beta TiNb surface, featuring wear-resistant and antibacterial properties, was successfully created by means of open-air fibre laser nitriding. Beta TiNb alloy was selected in this study as it has low Young's modulus, is highly biocompatible, and thus can be a promising prosthetic joint material. It is, however, necessary to overcome intrinsically weak mechanical properties and poor wear resistance of beta TiNb in order to cover the range of applications to loadbearing and/or shearing parts. To this end, open-air laser nitriding technique was employed. A control of single processing parameter, namely duty cycle (between 5% and 100%), led to substantially different structural and functional properties of the processed beta TiNb surfaces as analyzed by an array of analytical tools. The TiNb samples nitrided at the DC condition of 60% showed a most enhanced performance in terms of improving surface hardness, anti-friction, antiwear and anti-bacterial properties in comparison with other conditions. These findings are expected to be highly important and useful when TiNb alloys are considered as materials for hip/knee articular joint implants.

A promising laser nitriding method for the design of next generation orthopaedic implants: Cytotoxicity and antibacterial performance of titanium nitride (TiN) wear nano-particles, and enhanced wear properties of laser-nitrided Ti6Al4V surfaces

“…All these findings point to the fact that the nitrides formed at higher duty cycles were more brittle compared with that treated at a lower duty cycle. The influence of increased surface roughness and inhomogeneity as well as the inclusion of parent material in the nitride layer on the tribological properties have been reported elsewhere [20].…”

β-Ti Alloys for Orthopedic and Dental Applications: A Review of Progress on Improvement of Properties through Surface Modification

“…Chang et al [103] utilized the fully automated fiber laser system (Micro Laser Systems) for laser nitriding of Ti-30Nb-4Sn in the open air. A set of samples was prepared by varying the duty cycle from 5% to 100%.…”

Elastic-plastic properties of titanium and its alloys modified by fibre laser surface nitriding for orthopaedic implant applications

“…Among these techniques, laser remelting under nitrogen shielding (or laser nitriding) is one of the most effective surface modification techniques to enhance the surface hardness and wear resistance of Ti alloys by formation of TiN layer on the surface [18][19][20][21][22]. Unlike the TiN coating or layer created by other conventional methods e.g.…”

“…Unlike the TiN coating or layer created by other conventional methods e.g. physical/chemical vapor deposition (P/CVD), the TiN layer formed by open-air laser nitriding provides several advantages such as high speed, cleanliness, short treatment time, high precision, controllable accuracy, reproducibility and elimination of undesirable heating of the substrate thanks to the use of automated fiber laser system [18][19][20][21][22]. Most importantly, in conventional treatment methods, delamination of TiN coating from the substrate has long been a serious concern.…”

“…Most importantly, in conventional treatment methods, delamination of TiN coating from the substrate has long been a serious concern. Diffusion of high purity N2 into outermost region of the substrate under high pressure and energy, as well as formation of the deep, hard nitrided-TiN layer (thickness of >50 μm) that metallurgically bonded with the substrate effectively help alleviate the delamination in fibre laser nitriding [19][20][21][22]. Notwithstanding these key advantages, only limited studies have been devoted to the improvement of wear and corrosion resistance of Ti alloys via laser gas alloying with nitrogen to date.…”