Abstract
This study presents the fabrication and evaluation of (TiN + TiC)/TC4 hybrid nanocomposite cladding on TC4 titanium alloy substrates using a gas tungsten arc cladding process. Microstructural investigations using scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction confirmed the formation of denser claddings featuring both TiC and TiN reinforcement phases, along with intermetallic compounds such as AlN and Ti2N. Microhardness testing revealed a significant improvement in clad layer hardness reaching approximately 1100 HV compared to the substrate's 350 HV. This enhanced hardness translated into superior wear resistance. Pin-on-disc wear tests performed from room temperature up to 500 °C have shown the wear-rate acceleration with the temperature, particularly from 300 °C due to thermal softening, oxidation, and tribological changes. At 500 °C, abrasive wear, oxidative wear, and delamination were dominant. The wear resistance decreased by 375.7% compared to room temperature, with reductions of 183% and 259.7% at 100 °C and 300 °C, respectively. This highlights the critical role of dual TiN–TiC reinforcement in maintaining wear resistance at 300 °C. However, at 500 °C, elevated oxidation and matrix softening increased the coefficient of friction until 100 m of sliding distance, where stabilization occurred. Hybrid ceramic reinforcement improved abrasive wear resistance and limited oxidation wear by reducing tribo-oxide formation up to 300 °C. This enhancement in abrasive wear resistance further led to a change in wear mechanisms from two-body to three-body abrasion. Adhesion and delamination wear were more prominent at lower sliding velocities and elevated temperatures due to matrix softening and increased material transformation into debris. TiC and TiN reinforcement particulates improved wear resistance at high temperatures by mitigating softening effects and enhancing load-bearing capacity. The constructed wear mechanism maps described clear performance windows, providing a robust framework for selecting optimal parameters to enhance the wear performance and improve the operational lifespan of hybrid composite claddings in demanding tribological environments.
