High-Temperature Wear Behavior and Mechanisms of Self-Healing NiCrAlY-Cr3C2-Ti2SnC Coating Prepared by Atmospheric Plasma Spraying

Abstract

In engineering applications, it is crucial to extend service life by reducing the coefficient of friction (COF) and wear rate to improve dry wear resistance. This work investigates the tribological properties of NiCrAlY-Cr₃C₂-Ti₂SnC coatings with different Ti₂SnC additions over a wide temperature range. Composite coatings with varying Ti₂SnC concentrations were deposited onto TC4 titanium alloy substrates using atmospheric plasma spraying. Pin-on-disk wear tests were utilized to evaluate the tribological performance of the coatings, including the friction coefficient and wear rate, from room temperature to 800 °C. The wear mechanism of the coating was determined using SEM and a 3D profiler. The results demonstrate that the coating containing 30 wt.% Ti₂SnC (NC-30TSC) exhibits the lowest friction coefficient (0.29) and wear rate (4.89 × 10⁻⁵ mm³·N⁻¹·m⁻¹) at 800 °C. The composite coatings containing Ti₂SnC exhibited a decreased coefficient of friction and wear rate due to the high-temperature decomposition products of Ti₂SnC, such as TiO₂ and TiC. The wear mechanisms of the NC-30TSC coating were adhesive and fatigue wear at 300 °C, adhesive and oxidation wear at 600 °C, and oxidation wear at 800 °C. Additionally, the prefabricated cracks on the surface of the NC-30TSC coating healed after isothermal treatment, demonstrating excellent self-healing performance.