金属缝隙腐蚀的成因及实验验证

在制品和工程结构中,缝隙腐蚀是一种很普遍且隐蔽的局部腐蚀,其结果会导致构件强度降低,既降低服役寿命,也存在安全隐患。指出缝隙腐蚀发生的三个必要条件——制品或工程结构中有金属或合金、有缝隙的存在、缝隙内有腐蚀介质滞留,概述了缝隙腐蚀的特征及三个阶段。分析了缝隙腐蚀的影响因素,包括金属性质、环境因素(溶液中氧、氯离子浓度,温度,p H值以及溶液的流速)和缝隙的几何形状。介绍了在实验室用三氯化铁溶液验证不锈钢及其合金的缝隙腐蚀敏感性的基本步骤,提出了在工程实际中如何预防缝隙腐蚀的基本思路。

Cause of Metal Crevice Corrosion and Experiment Verification

As a very common and concealed local corrosion in products and engineering structures, crevice corrosion will not only reduce service life and component strength, but also result in a security issue. Three essential conditions, presence of metal or alloy, existence of crevices and residue of corrosion medium in products and engineering structures, were necessary for crevice corrosion. The characteristics and three stages of crevice corro-sion were summarized. The influence factors of crevice corrosion, including metal properties, environmental fac-tors (dissolved oxygen, chlorine ion concentration, temperature, pH value and the velocity of the solution) and crevice geometry were analyzed. The essential steps of examining crevice corrosion sensitivity of stainless steel and alloy in laboratory with ferric chloride solution were introduced. The basic idea of crevice corrosion resistance was put forward in engineering practices.