安徽省电网用镀锌钢的大气腐蚀及其影响规律

Study on the Atmospheric Corrosion of Galvanized Steel in the Anhui Province Power Grid and Its Influence Law

为评估安徽省大气环境下电网镀锌钢构件的腐蚀状态,针对自然曝露1a、3a后的镀锌钢试样,利用SEM、EDS及XRD等表征手段开展腐蚀产物组成及其形貌测试,探讨其大气腐蚀机理;采用失重法获取镀锌钢试样的腐蚀速率,结合灰色关联分析,揭示主要环境因素对镀锌钢试样大气腐蚀速率的影响规律。结果表明,镀锌钢试样大气腐蚀产物为ZnO及少量的Zn_(5)(OH)_(6)(CO_(3))_(2)和Zn_(4)(OH)_(6)SO_(4);腐蚀层表面胞状凸起由层片状的Zn_(5)(OH)_(6)(CO_(3))_(2)、Zn_(4)(OH)_(6)SO_(4)构成,呈菊花状。腐蚀层结构致密,与镀锌层结合紧密,具有良好的保护性,镀锌钢腐蚀程度低。主要环境因素对安徽省域镀锌钢试样大气腐蚀速率影响程度排序为:温度>相对湿度>O_(3)>NO_(2)>PM_(2.5)>PM_(10)>SO_(2)。温度及大气相对湿度的影响较大,而SO_(2)的影响较小。

In order to evaluate the corrosion state of power grid galvanized steel components in the atmospheric environment of Anhui Province,galvanized steel samples,which were naturally exposed for 1 and 3 a,respectively,were analyzed using scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDX)and X-ray diffractometer(XRD)to investigate the compositions and morphologies of the corro-sion products,thereby revealing their atmospheric corrosion mechanisms.Meanwhile,the corrosion rates of the galvanized steel samples were determined using the weight-loss method,combined with grey correlation analysis,to ascertain the influence law of major environmental factors on the atmospheric corrosion rate of the galvanized steel samples.Results showed that the atmospheric corrosion products of the galvanized steel samples consisted of ZnO and minor amounts of Zn_(5)(OH)_(6)(CO_(3))_(2)and Zn_(4)(OH)_(6)SO_(4).The surface of the corrosion layer featured cellular pro-trusions composed of flaky Zn_(5)(OH)_(6)(CO_(3))_(2)and Zn_(4)(OH)_(6)SO_(4),forming chrysanthemum-like patterns.The structure of the corrosion layer was dense and closely bonded to the galvanized layer,providing effective protection,and thus,the corrosion degree of the galvanized steel was low.The major environmental factors affecting the atmospheric corrosion rate of the galvanized steel samples in Anhui Province were ranked as follows:temperature>relative humidity>O_(3)>NO_(2)>PM_(2.5)>PM_(10)>SO_(2).Temperature and atmospheric relative humidity had a more signif-icant impact,whereas the influence of SO_(2)was minimal.