针对超临界水氧化过程中材料腐蚀严重的问题,采用等离子喷涂技术在316 L不锈钢上分别喷涂约0.2 mm的Al2O3,ZrO2和TiO2涂层以提高其耐腐蚀性.采用间歇式超临界水氧化反应釜研究了各涂层试样在500℃、25 MPa、氧浓度1000 mg.L-1条件下,连续腐蚀80 h的腐蚀特性.对各涂层试样的结合强度及腐蚀前后表面及截面的形貌、元素分布等进行了表征.结果表明,Al2O3、ZrO2和TiO2涂层的结合强度分别为26.639 N.mm-2、24.526 N.mm-2和40.607 N.mm-2.经腐蚀实验后,Al2O3涂层表面呈沟壑状,出现较多的孔洞和缝隙,涂层几乎完全脱落;ZrO2涂层表面原平整致密涂层受到破坏,呈现断裂及碎片化涂层形貌,涂层因腐蚀变薄,剩余厚度约为0.15 mm;TiO2涂层表面相对比较致密,涂层厚度未发现明显降低,呈现较好的耐腐蚀性能.该研究结果为超临界水氧化过程中金属材料腐蚀防控方法提供一种新思路.%In order to solve corrosion problems of metal materials during supercritical water oxidation (SCWO) processes, Al2O3, ZrO2 and TiO2 coatings with thickness of 0.2 mm were prepared on the surface of 316L stainless steel by atmospheric plasma spraying (APS). Corrosion of the coated samples was evaluated in a batch reactor at 500 ℃ and 25 MPa with an oxygen concentration of 1000 mg.L-1 for 80 h. The adhesive strength of the coated samples was tested, and the surface and cross-section morphologies along with element distributions of fresh and corroded samples were analyzed. The results show that the adhesive strength of the Al2O3, ZrO2, and TiO2 coatings is 26.639, 24.526 and 40.607 N.mm-2, respectively. The surface morphology of Al2O3/316 L show gully erosion with many pores and cracks after being exposed in SCW, and most of the coating can be peeled off. The original dense ZrO2 coating becomes fragmented in supercritical water, and the residual thickness of the coating is ~ 0.15 mm. The surface morphology of TiO2 coating is relatively dense and the thickness of the coating is not decreased obviously in supercritical water. The TiO2 coating exhibits better corrosion resistance compared with the Al2O3 and ZrO2 coatings. The results provide a new approach for corrosion prevention of metal materials during SCWO processes.
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