锌铝合金粉中Al含量对无铬达克罗涂层耐蚀性的影响

Effect of Aluminum Content in Zinc-Aluminum Alloy Powder on Anticorrosion Behavior of Chromium-Free Dacromet Coating

为获得表面形貌良好、耐蚀性能优异的无铬锌铝合金涂层,采用4种不同Al含量的片状Al-Zn合金粉替代传统达克罗涂层所用的锌铝混合粉制备涂层,将涂层浸入Na Cl溶液中进行加速浸泡腐蚀。采用扫描电镜、能谱仪、X射线衍射仪分析涂层腐蚀形貌、成分及物相,研究了Al含量对合金粉末涂层性能的影响。结果表明,当合金粉中Al的质量分数低于55%时,涂层的防护寿命随着Al含量的增大而增加,采用Al含量为55%的片状合金粉制备的无铬达克罗涂层的耐蚀性最好。

Four kinds of flake-like Zn-Al alloy powders with different Al contents were adopted to replace Zn-Al alloy powder used for conventional dacromet coating in order to obtain Cr-free Zn-Al coatings with good surface morphology and corrosion resistance.The as- prepared Cr-free Zn-Al dacromet coatings were immersed in NaCl aqueous solution to undergo accelerated corrosion test.The corroded surface morphology,composition and phase species of the Cr-free dacromet coatings were analyzed by scanning electron microscopy,energy dispersive spectrometry and X-ray diffraction,and the effect of the Al content in the Zn-Al alloy powders on the anticorrosion behavior of the coatings was investigated.Results indicated that,when the Al content in the Zn- Al alloy powders was below 55%(mass fraction;the same hereafter),the protective life of the coatings tended to increase with increasing Al content;and in particular,the Cr-free dacromet coating made from the flake-like Zn-Al alloy powder containing 55%Al exhibited the best anticorrosion behavior.