含氯介质超临界水氧化过程中几种镍基合金腐蚀的实验研究

Corrosion of Some Ni-base Alloy Stainless Steels in Chloride Solution for Supercritical Water Oxidation Process

超临界水氧化过程中,含氯化合物水溶液对普通不锈钢具有极强的腐蚀性.使用超临界水氧化反应装置,研究了4种镍基合金不锈钢试样(1Cr18Ni9Ti,316L,0Cr18Ni12Ti和QLC12)在超临界水氧化过程中(400～620℃,28～32MPa)处理含氯废水时的腐蚀情况.经过30d的实验,用金相光学显微镜和扫描电子显微镜观测试样腐蚀的形貌.结果表明,4种合金在15%(ω)含氯水溶液中经过超临界水氧化反应均存在腐蚀.对腐蚀速率进行了测试,其中1Cr18Ni9Ti和316L腐蚀速率较大,而QLC12腐蚀速率最小,为0.06mm/a,可用于制造反应器.实验发现0Cr18Ni12Ti存在晶间腐蚀现象.同时对腐蚀机理进行了分析.

Generally stainless steels may be corroded awfully by chloride aqueous solution in supercritical water oxidation process. The Ni-based alloy stainless steel samples, such as 1Cr18Ni9Ti, 316L, 0Cr18Ni12Ti and QLC12, were tested by supercritical water oxidation （at 400-620 ℃, 28-32 MPa） in the 15%（ω） chloride wastewater solution for 30 d on supercritical water oxidation system. The results showed that all the alloys exhibited the corrosion observed by optical microscope and SEM. 1Cr18Ni9Ti and 316L stainless steels suffered pit corrosion. Intergranular corrosion was found in 0Cr18Ni12Ti. Corrosion rate was tested for each alloy, the corrosion rates of 1Cr18Ni9Ti and 316L were higher, but that of QLC12 was the least, being 0.06 mm/a, which can be used as reactor material. The mechanism of corrosion was also examined.