材料期刊网

热镀锌被广泛用于钢筋防锈蚀,为探求不同气体氛围以及不同介质环境中镀锌层对钢基体的电化学保护作用的差异,在N2、饱和CO2、空气3种气氛下,运用pH值、电位监测、X射线衍射(XRD)等方法分析碳钢和镀锌钢在普通混凝土及模拟混凝土孔隙液中的腐蚀行为.结果表明:在N2、饱和CO2、空气3种气氛下混凝土的pH值最终分别为12.50、7.41、10.06,模拟液的pH值最终分别为12.50、6.05、8.05;在N2气氛下,介质对最终电位影响不大,碳钢和镀锌钢都表现为较稳定的钝化状态;在CO2气氛下,碳钢和镀锌钢的电位都剧烈下降,模拟液介质中的碳化情况比混凝土中的严重,其中模拟液中碳钢的电位稳定,而镀锌铜的电位在第9～13 d有一段上升,此时镀锌钢的腐蚀产物主要为碳酸锌;在空气气氛下,镀锌钢在2种介质中电位都呈现上升趋势,与碳钢的电位差值逐渐减少,其在混凝土中波动更为剧烈,表面生成的锌酸钙随着溶液pH值的降低同时存在溶解与生成现象.

The corrosion behaviors of carbon steel and galvanized steel in the pore fluid of common concrete and simulated concrete under N2 atmosphere,saturated CO2 atmosphere and air atmosphere were characterized by pH value,potential monitoring and X-ray diffraction (XRD).Results showed that the pH values of concrete under N2 atmosphere,saturated CO2 atmosphere and air atmosphere were 12.50,7.41 and 10.06,respectively,and these under simulated concrete were 12.50,6.05 and 8.05.Under N2 atmosphere,mediums had little influence on the final potentials,and carbon steel and galvanized steel performed stable passivation state.Under CO2 atmosphere,the potentials of both carbon steel and galvanized steel decreased sharply,and the carbonation degree in simulated medium was more serious than that in concrete.Meanwhile,the potential of carbon steel in simulated liquid was steady,while the potential of galvanized steel increased during 9-13 d,and the corrosion products of carbon steel were mainly composed of zinc carbonate.Under air atmosphere,the potentials of galvanized steel increased in two kinds of medium,and the difference value to potential of carbon steel gradually decreased.Furthermore,the potential fluctuation in concrete was sharply,and as the pH value reduced,the calcium zincate deposited on surface of galvanized steel could be dissolved and generated at the same time.