Molecular Dynamics Simulation of the Performance of CoCrFeNiCu High-Entropy Alloy Coatings in Pump Valve Erosion Environments

In the drilling environment, a large number of microparticles will be mixed between the drill pipe joint and the sleeve, which will cause serious wear. Therefore, it is very important to enhance the erosion resistance of the pump valve. In this study, a new high-entropy alloy material CoCrFeNiCu was used as a coating material, and three coating structures of single crystal, polycrystalline, and polycrystalline-twinning were established for comparative analysis. The results show that the single crystal coating has the best protection performance for the pump valve, followed by the polycrystalline coating, and the protection performance of the polycrystalline-twinning coating is relatively poor. Further analysis found that the reason for the poor performance of the polycrystalline-twinning coating is that although the strengthening effect of the twin boundaries can increase the grain hardness, it also increases the hardness difference between the grain and the multigrain boundary, resulting in stress concentration at the multigrain boundary, thereby reducing its protective effect. This finding is of great significance for optimizing the structure of high-entropy alloy coating to improve the erosion resistance of pump valves.