Alloy 316 stainless steel (SS) is an important candidate material for supercritical water oxidation facilities, but severe corrosion negatively affects its life-span and potential application. In this work, ZrO₂ and TiO₂ were coated on the 316 SS substrate by air plasma spraying and then exposed in oxygenated sub- and supercritical water. The results show that the coatings could greatly improve the corrosion resistance of 316 SS in oxygenated sub- and supercritical water in the range from 300 °C to 480 °C at 24 MPa with 3 wt% of oxygen content for 100 h. Increasing temperature accelerated the corrosion of tested TiO₂- and ZrO₂-coated samples. ZrO₂ and TiO₂ coatings could inhibit the outward diffusion of metal elements in the 316 SS substrate and the inward diffusion of oxygen. The oxide film of the ZrO₂-coated sample was composed of Cr₂O₃, Fe₃O₄, Fe₂O₃, NiFe₂O₄ and NiCr₂O₄, while that of the TiO₂-coated sample consisted of Cr₂O₃, Fe₃O₄ and Cr₂MoO₆ at 480 °C. Compared with the ZrO₂ coating, the TiO₂ coating exhibited better protective effects on reducing 316 SS corrosion in oxygenated supercritical water. The TiO₂- coated sample led to lower absolute values of weight changes, more uniform and denser corrosion surface, and better inhibition on the outward diffusion of metal elements (especially Ni) and on the inward diffusion of O. This suggests that the TiO₂ coating on the 316 SS substrate via air plasma spraying is an effective approach to improve 316 SS corrosion resistance in tested oxygenated supercritical water.

316不锈钢（SS）合金是超临界水氧化设施的重要候选材料，但严重腐蚀会对它的寿命和潜在应用产生负面影响。在这项工作中，通过空气等离子喷涂将ZrO ₂和TiO ₂涂覆在316 SS基板上，然后将其暴露在含氧的亚临界和超临界水中。结果表明，该涂层可以在300℃至480℃，24 MPa，含氧量3 wt％的条件下持续100 h改善含氧亚临界和超临界水中316 SS的耐腐蚀性。温度升高加速了测试的TiO ₂和ZrO ₂涂层样品的腐蚀。ZrO ₂和TiO ₂涂层可以抑制316 SS基材中金属元素的向外扩散和氧气的向内扩散。ZrO ₂涂层样品的氧化膜由Cr ₂ O ₃，Fe ₃ O ₄，Fe ₂ O ₃，NiFe ₂ O ₄和NiCr ₂ O _4组成，而TiO ₂涂层样品的氧化膜由Cr组成。480°C下的₂ O ₃，Fe ₃ O ₄和Cr ₂ MoO ₆。与ZrO ₂涂层相比，TiO₂涂层在减少含氧超临界水中的316 SS腐蚀方面表现出更好的保护作用。涂覆TiO _2的样品导致重量变化的绝对值降低，腐蚀表面更均匀且致密，并且对金属元素（尤其是Ni）的向外扩散和O的向内扩散的抑制作用更好。这表明TiO ₂通过空气等离子喷涂在316 SS基材上进行涂层是一种有效的方法，可以提高测试过的含氧超临界水中的316 SS耐腐蚀性。