电弧喷涂锌涂层的酸雨腐蚀性能

Corrosion performance of arc-sprayed Zn coating in simulated acid rain environment

热镀锌涂层因具有优越的耐腐蚀性、涂装性能等被广泛应用于工业生产众多领域,成为金属材料在户外工作环境下防腐蚀的有效措施之一。为研究热喷涂锌涂层在酸雨中的腐蚀行为,采用电弧喷涂技术在Q235碳素结构钢表面喷涂锌涂层,模拟酸雨腐蚀环境,在腐蚀液pH值改变的情况下,采用SEM,XRD,硬度测试及失重分析等手段,分析不同pH值溶液腐蚀后涂层的表面形貌和腐蚀产物,及试样的硬度变化和腐蚀速率情况。结果表明,锌涂层的表面腐蚀会随着模拟酸雨溶液pH值的降低而加重,其表面腐蚀产物逐渐增多,腐蚀产物的形貌由小块状逐渐变成羽针状和岛状,主要成分为Zn(OH)_(2),ZnSO_(4)和Zn_(4)SO_(4)(OH)_(6)·3H_(2)O;涂层表面硬度最高为23.4 HV、最小腐蚀速率为0.21×10^(-4)g/(m^(2)·h),但当模拟酸雨溶液pH值由7降至2.8时,涂层表面硬度降低约12%,腐蚀速率约增大至最小值的26倍;模拟酸雨溶液pH值在5~2.8时,溶液对锌涂层的腐蚀比较严重。

Hot-sprayed Zn coating has been widely used in many industrial fields because of its excellent corrosion resistance and coating performance.It has become one of the effective measures to prevent corrosion of metal materials in outdoor working environment.In order to study the corrosion behavior of hot-sprayed Zn coating in acid rain,hot-sprayed Zn coatings on Q235 carbon structural steel were prepared by arc spraying technology.Surface morphology,corrosion product,hardness and corrosion rate of coatings were studied by means of scanning electron microscopy(SEM),X-ray diffraction(XRD),hardness test and weightlessness analysis in simulated acid rain for different pH.The results showed that surface corrosion of Zn coatings were increase with decrease of pH value of simulated acid rain solution,corrosion products on the surface of Zn coatings increased,morphology gradually changed from small block to pinnate and island,and the main components were Zn(OH)_(2),ZnSO_(4)and Zn_(4) SO_(4)(OH)_(6)·3H_(2)O.The maximum surface hardness of coatings was 23.4 HV,and the minimum corrosion rate was 0.21×10^(-4)g/(m^(2)·h).However,when pH value of simulated acid rain solution decreased from 7 to 2.8,surface hardness of coatings decreased about 12%,and corrosion rate increased to 26 times of the minimum value.When pH value of simulated acid rain solution ranged from 5 to 2.8,corrosion of Zn coatings was more serious.