在高温硝酸与丙烷蒸气环境中R60702工业纯锆的腐蚀行为

Corrosion Behavior of R60702 Industrial Pure Zirconium in High Temperature Nitric Acid and Propane Vapor

通过均匀腐蚀试验研究了R60702工业纯锆在高温硝酸和丙烷蒸气环境中的腐蚀行为。结果表明:R60702纯锆在260℃的硝酸与丙烷蒸气中的腐蚀速率极低,表面氧化膜较致密,厚度约为15μm;在430℃的硝酸与丙烷蒸气中的腐蚀速率较高,表面氧化膜厚度约为50μm,由外层疏松氧化膜和内层致密氧化膜组成,氧化膜中存在微裂纹,且部分氧化膜脱落;表面氧化膜均主要由单斜ZrO2和四方ZrO2组成;当温度为260℃时,致密氧化膜对基体起到保护作用;当温度为430℃时,氧化膜保护作用降低,氧化膜增厚并产生应力松弛,导致四方ZrO2转变为单斜ZrO2,氧化膜体积膨胀并产生微裂纹,裂纹扩展合并导致氧化膜脱落。

The corrosion behavior of R60702 industrial pure zirconium in high temperature nitric acid and propane vapor was studied by uniform corrosion test.The results show that the R60702 pure zirconium had the very low corrosion rate in nitric acid and propane vapor at 260℃,and a dense oxide film with thickness of about 15μm was formed on the surface.The corrosion rate in nitric acid and propane vapor at 430℃was relatively high;the surface oxide film with thickness of about 50μm consisted of an outer loose oxide film and an inner dense oxide film;there were micro-cracks in the oxide film and part of the oxide film peeled off.The surface oxide film was mainly composed of monoclinic ZrO2 and tetragonal ZrO2.When the temperature was 260℃,the dense oxide film protected the substrate.When the temperature was 430℃,the protective effect of the oxide film decreased,leading to the thickening of the oxide film and stress relaxation,which caused the transformation of tetragonal ZrO2 to monoclinic ZrO2,expansion of the oxide film volume and generattion of micro-cracks.The cracks expanded and merged,resulting in the peeling of the oxide film.