Sol–Gel-Derived Ni(3)Al Coating on Nickel Alloy for Oxidation Resistance in Supercritical Water Environments

Although nickel-based alloys are widely used in industries due to their oxidation and corrosion resistance, the pursuit of better performance in harsh environments is still a great challenge. In this work, we developed a sol–gel method to synthesize Ni(3)Al coating on a nickel alloy, assisted by a post-annealing process, and investigated the oxidation-resistant performance. The coating thickness can be controlled by designing the deposition times, which keep the pure Ni(3)Al phase stable. In addition, the surface morphologies indicate that the coating is compact without obvious voids or cracks. Furthermore, the oxidation-resistant property of the coating was investigated by carrying out a supercritical water oxidation experiment. The crystalline structure and surface morphology of the samples before and after 72-h oxidation demonstrated the superior oxidation resistance of the coating. This work provides a convenient method to fabricate an oxidation-resistant coating on a nickel-based alloy, which would be significant for prolonging the service life of vessels under oxidation conditions, especially for supercritical water reactions.