S_2O_3^(2-)对Ni基合金671在NaCl水溶液中的点蚀行为的影响

EFFECT OF THIOSULFATE ION ON PITTING OF NICKEL-BASED ALLOY 671 IN SODIUM CHLORIDE SOLUTION

采用电化学测试方法对一种新兴的超临界水氧化 (SCWO)废物处理技术设备用材———Ni基合金 6 71在含S2 O2 -3 根离子的NaCl水溶液中的点蚀行为进行了研究 .结果表明 ,在纯Na2 S2 O3 水溶液中 ,6 71合金不发生点蚀 ;而在纯NaCl水溶液中 ,6 71合金存在发生点蚀的氯离子临界浓度 ,且其耐蚀性优于Ni基合金 6 90 ;在向NaCl溶液中添加不同浓度的S2 O2 -3 根离子时 ,随添加S2 O2 -3 浓度的逐渐提高 ,6 71合金的点蚀逐渐受到抑制 ,耐蚀性能提高 ,该特性将使得 6 71合金在用于SCWO反应的设备制造材料方面极具优势 .

In sodium chloride solution containing thiosulfate ion,pitting behavior of nickel-based alloy 671,which will be used as candedate construction material in supercritical water oxidation(SCWO) devices,was investigated by electrochemical testing methods.The results show that in plain sodium thiosulfate solution alloy 671 is immune to pitting.While a critical chloride ion concentration for pitting commence of alloy 671 is exist in sodium chloride solution,and where the corrosion resistance of alloy 671 is higher than nickel-based alloy 690.Furthermore with increasing the addition of sodium thiosulfate into sodium chloride solution,the pitting corrosion of alloy 671 is obviously inhibited.This characteristic makes alloy 671 competitive as an SCWO construction material.