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用模拟闭塞电池研究1Cr18Ni9Ti奥氏体不锈钢在Cl~-+NO_3~-(或NO_2~-)溶液中闭塞区内化学和电化学状态的变化。当外部溶液中NO_3~-或NO_2~-达到一定浓度时,闭塞区内pH下降比在单纯Cl~-溶液中缓慢,并且趋于一极限值(pH(?)2)后,即不再下降。裂尖溶液内Cl~-与NO_3~-克当量比例和外部主溶液接近,但裂尖溶液变浓直到饱和。当1法拉第电量通过闭塞区时,大约有0.5～0.7克当量的Cl~-+NO_3~-迁入闭塞区。NO_2~-迁入裂尖后与H~+和金属离子反应而消耗。溶液中加入不同浓度NO_3~-或NO_2~-后,使破裂电位变为更正_1裂尖处于钝态,表明NO_3~-和NO_2~-均有缓蚀作用。
The changes of chemical and electrochemical states in the occluded area of 1Cr18Ni9Ti austenitic stainless steel in Cl ~ - + NO_3 ~ - (or NO_2 ~ -) solution were studied by simulated occlusion cells. When the concentration of NO_3 ~ - or NO_2 ~ in the external solution reached a certain concentration, the decrease of pH in the occluded area was slower than that in the pure Cl ~ - solution and did not decrease any more when it reached a limit (pH 2) . The ratio of Cl ~ - to NO_3 ~ g in the crack tip solution is close to that of the external main solution, but the crack tip solution becomes thick until it reaches saturation. When a Faraday electricity passes through the occlusion zone, about 0.5 to 0.7 gram equivalent of Cl ~ - + NO_3 ~ moves into the occlusion zone. NO_2 ~ - moved into the crack tip and H ~ + and metal ions and consumed. After adding NO_3 ~ - or NO_2 ~ - in solution, the rupture potential changed to a corrected _1 crack tip in the passive state, indicating that NO_3 ~ - and NO_2 ~ - all had corrosion inhibition.