Effect of WC-10Co-4Cr coating on the fretting tribo-corrosion behavior of an Inconel 690 alloy tube under salt spray steam environment

Fretting tribo-corrosion commonly occurs on the outer surface of Inconel 690 alloys, which are widely applied as steam generator tubes of nuclear power plants. This study utilizes a fretting wear test rig and an electrochemical corrosion workstation to reveal the fretting tribo-corrosion behaviors of substrate samples and Inconel 690 alloy tube samples treated with WC-10Co-4Cr coating under 150 degrees C and 300 degrees C fretting salt spray steam environments. Results show that the fretting tribo-corrosion degree and rate of Inconel 690 alloy are considerably reduced after coating treatment. These results are attributed to the fact that the mechanical properties of the coating-treated Inconel 690 alloy tube are better than those of the substrate, and the former can effectively resist fretting wear, external stresses, and tribo-corrosion. Simulation stress analysis further confirms that the stress on the coating surface is lower than that on the substrate, which is contributed to the improved performance of the coating surface. The primary fretting damage mechanisms are abrasive wear, plastic deformation, and fatigue spalling.