Tribological and oxidation behaviors of TiN reinforced Co matrix composite coatings on Inconel718 alloy by laser cladding

Abstract

To improve the tribological properties of Inconel718 superalloy under harsh conditions such as high temperature, the Co/TiN composite coatings were created by laser cladding on its surface. Phase analysis, microstructure morphology, and microhardness, wear, and oxidation experiments were used to evaluate the tribological behaviors of the composite coatings at room temperature (RT) and 600 °C, as well as the oxidation resistance at 800 °C. The results of phase analysis show that the coatings mainly contain γ-Co, (Fe,Ni) solid solution, intermetallics FeNi3 and TiN. Among the three coatings, Co-6%TiN coating has the highest microhardness, which is 1.4 times that of the substrate (279.3 HV0.5). In addition, it also shows the best wear resistance and oxidation resistance. The wear rate is 1.36 × 10−5 mm3/(N∙m) and 0.94 × 10−5 mm3/(N∙m) at RT and 600 °C, and the oxidation rate constant is 8.7634 mg2∙cm−4∙h−1, with the wear mechanism of plastic deformation, abrasive and oxidation wear. This work investigated Co/TiN composite coating at high temperatures for proposing a novel solution for improving the properties of Inconel718.