A review on Inconel 625 alloy metal matrix composite coatings

Inconel 625 alloy exhibits excellent high-temperature performance and corrosion resistance and is frequently used as a protective coating material for oxidation resistance, corrosion resistance, and wear resistance. However, the relatively low hardness of Inconel 625 alloy limits its wear protection capability. To improve the wear resistance of the coating, a certain amount of hard ceramic reinforcing particles is typically added into the Inconel 625 alloy matrix to form a metal matrix composite coating. The research status of Inconel 625 alloy composite coatings was reviewed. The different preparation methods of composite coatings and the characteristics of coatings prepared with various types of reinforcing particles were systematically reviewed; the influencing factors and action mechanisms of wear resistance enhancement in composite coatings were summarized; the decomposition and agglomeration issues of reinforcing particles in the coatings, along with the corresponding solutions, were analyzed. The analysis indicates that laser cladding is the most commonly used process for preparing Inconel 625 alloy composite coatings; the most commonly used reinforcing phases are WC and TiC; the most important factor affecting the wear resistance of the composite coatings is the content of reinforcing particles. Moreover, process parameters, as well as the type, size, and shape of reinforcing particles, influence the decomposition of reinforcing particles; the addition of carbon nanotubes can effectively restrict the agglomeration of reinforcing particles.