Laser cladding Ni60-SiC/Ti3SiC2 self-lubricating composite coatings on IN718 alloy: Wear mechanisms and oxidation behaviors

To enhance the service performance of IN718 alloy under severe working conditions, the self-lubricating composite coating of Ni60-SiC/Ti3SiC2 was fabricated on its surface using laser cladding. By systematically analyzing the microstructure and properties of composite coatings, the wear mechanism at different temperatures and the oxidation behavior at 800 degrees C of coatings were discussed in depth. The results demonstrate that an increase in coatings' microhardness by a factor of 1.9-3.1 over IN718 was achieved, benefiting from the fine-grained and solid-solution strengthening actions, and the hard phases such as C23C6, Ni3Si, TiC distributed diffusely inside the coatings. The tribological performance of coatings was also significantly improved, in which the coating with 10 wt% Ti3SiC2 added had the lowest wear rates of 2.13 and 3.57 x 10-5 mm3/N & sdot;m at RT and 600 degrees C, respectively, which were reduced by 82.74 % and 87.43 % compared to the substrate. When the test temperature changes from RT to 600 degrees C, the main wear form of coatings changes from adhesive and abrasive wear to oxidative wear. With the Ti3SiC2 content increasing, the oxide film is gradually dense and uniform, and the oxidation resistance is significantly improved.