Effects of Al₂O₃-TiO₂ Composite Particles on the Microstructure and High-Temperature Wear Behavior of Laser Cladding Inconel 718-Based Lubricant Coatings

Abstract

To address the issue of wear failure in Inconel 718 nickel-based alloy under wide temperature conditions, two different contents of Al2O3+TiO2 particles(10%, 20%, mass fraction) were selected as ceramic reinforcement phases. Two types of Inconel 718-MoS2-Al2O3-TiO2 high-temperature wear-resistant lubricating composite coatings were prepared using laser cladding technology. The microstructure, mechanical properties and tribological behavior of the composite coatings were systematically investigated to provide data support for their application in the field of tribology. Results showed that the composite coatings were primarily composed of γ-Ni solid solution, γ'-Ni3(Ti, Al) intermetallic compounds, Ti3O5 and Al2O3 ceramic reinforcement phases, as well as MoS2 lubricating phase. When the content of TiO2 and Al2O3 reached 20%, higher levels of Ti3O5 and Al2O3 contributed to increased hardness and elastic modulus of the coatings, with a maximum microhardness of up to 455 HV0.3. However, this led to coarser grains of Ti3O5 and Al2O3 phases, which were unfavorable for enhancing the elastic modulus and resistance to plastic deformation. At friction temperatures ranging from room temperature to 200 ℃, the friction coefficient and wear rate of the composite coatings with 10% TiO2 and Al2O3 content significantly increased, reaching maximum values. Wear mechanisms were mainly attributed to abrasive wear and delamination. As the temperature increased to 400 ℃, the formation of a continuous oxide film on the coating abrasion surface led to a significant reduction in wear rate. When the temperature reached 600～800 ℃, both types of composite coatings formed continuous smooth oxide films on the friction surfaces, exhibiting lubricating effects and significantly improving tribological performance, especially with a reduction in wear rate by one order of magnitude compared to Inconel 718 alloy coatings. When the content of TiO2 and Al2O3 reached 20%, the composite coatings demonstrated superior tribological performance at intermediate to high temperatures. A comparative analysis revealed that the Inconel 718-MoS2-Al2O3-TiO2 composite coatings exhibited better tribological performance than Inconel 718 alloy coatings across temperatures ranging from room temperature to 800 ℃.

Keywords

• laser cladding; nickel-based composite coatings; high temperature wear-resistant; self-lubrication at wide temperature range