处理时间对建筑用热镀锌板镧盐转化膜耐蚀性的影响

Effect of Treatment Time on Corrosion Resistance of Lanthanum Salt Conversion Films on Hot Galvanized Plate Used in Construction

将热镀锌板浸入含有柠檬酸的处理液中制备镧盐转化膜,并研究处理时间对镧盐转化膜形貌、表面成分、物相及耐蚀性的影响。结果表明:镧盐转化膜含有Zn、La、C和O元素,主要由ZnO和La_(2)O_(3)相组成。随着处理时间延长,La元素质量分数呈增加趋势,伴随着Zn元素质量分数降低,镧盐转化膜的形貌先趋于致密而后表面龟裂出现脱落现象,导致耐蚀性先逐步提高而后下降。对热镀锌板化学转化处理8 min后,表面出现白锈的时间延长了约30 h,耐醋酸铅点滴时间延长了约40 s,膜层电阻和电荷转移电阻都提高约2倍,耐蚀性明显提高。

Hot galvanized plate was immersed in a treatment solution containing citric acid to prepared lanthanum salt conversion films,and the effect of treatment time on the morphology,surface composition,phase and corrosion resistance of lanthanum salt conversion films was studied.The results showed that lanthanum salt conversion film contains Zn,La,C and O elements,and was composed of ZnO and La_(2)O_(3) phase.With the extension of treatment time,the mass fraction of La element shows an increasing trend along with the decrease of the mass fraction of Zn element,and the morphology of lanthanum salt conversion films tend to be dense at first and then the surface cracked and fell off,leading to the corrosion resistance increased at first and then decreased.When chemical conversion treatment of hot galvanized plate for 8 min,the time of white rust appeared on the surface was prolonged by about 30 h,the lead acetate resistance time was prolonged by about 40 s,and the film resistance and charge transfer resistance were increased by about two times,indicating that the corrosion resistance of hot galvanized plate was significantly improved.