Corrosion and friction characteristics of microarc oxidation coating on Zr-4 alloy

To improve the anti-wear and anti-corrosion of core structural materials of nuclear reactors, a relatively dense ceramic coating is fabricated on the Zr-4 alloy surface by microarc oxidation (MAO). Results show that compared with the substrate, the corrosion potential (−0.212V) of MAO coating in the simulated corrosion solution of a nuclear reactor (0.1 mol/L LiOH) exhibits a positive shift, and the corrosion current density (7.50 × 10⁻¹¹ A∙cm⁻²) decreases by four orders of magnitude. During the long-term immersion process of the coated samples, the impedance modulus value still remains above 107 Ω cm², indicating long-term corrosion protection. Moreover, under the GCr15-dry sliding condition, the friction coefficient of MAO coatings is high under various loads and is mainly attributed to abrasive wear. Under the wet lubrication sliding condition, the friction coefficient is low and stable at 0.35, with a good anti-friction effect. To summarize that, the MAO coating can provide sufficient long-term anti-corrosion and anti-wear protection for zirconium-based alloys, showing great potential in nuclear industry fields such as nuclear reactor cladding.