Influence of Deposition Parameters on the Mechanical Performance of Ti/TiN Coatings on Ti–51 at% Ni Alloy

Abstract

The Ti–51 at% Ni shape-memory alloy demonstrates remarkable functional attributes, including resistance to corrosion, pronounced pseudoelasticity, and high mechanical strength. Nonetheless, concerns regarding its biocompatibility arise due to the potential release of nickel ions during biomedical implantation. To address this limitation, the present investigation focused on optimizing Ti/TiN surface coatings on the alloy. Such coatings are anticipated to enhance the alloy’s surface integrity, particularly by increasing hardness to withstand external loading conditions. Moreover, achieving robust adhesion of the deposited layers is essential to mitigate any adverse effects associated with metallic ion release. Experimental analysis revealed that maximum adhesion strength was attained under processing conditions of 370 W DC power, 100 °C substrate temperature, 50 V bias voltage, and 5 sccm nitrogen flow. In contrast, peak hardness was observed at 370 W DC power, 150 °C, 75 V bias voltage, and 5 sccm nitrogen flow. Subsequent validation confirmed a 46.5% improvement in hardness, accompanied by a 9.7% increase in adhesion strength, thereby demonstrating effective bonding of the coatings to the alloy substrate. These findings establish a foundation for future research into the application of surface coatings to enhance the biocompatibility of titanium-based alloys.