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研究了Mg含量对Zn-6%Al合金镀层凝固组织及其耐腐蚀性能的影响。结果表明,Mg对合金镀层凝固组织和耐腐蚀性的影响明显,当Mg含量在3%以内时,随着Mg含量的增加,镀层凝固组织中出现了耐腐蚀相MgZn2,晶粒不断细化,形成了Zn/Al/MgZn2三元共晶,并且随着Mg含量升高更加均匀致密,镀层的耐腐蚀性不断增强;当Mg含量达到3%时,镀层的耐腐蚀性能最好;Mg添加量超过4%后,镀层耐蚀性有所下降,进一步添加Mg镀层会出现漏镀等质量缺陷。XRD分析表明,含Mg镀层表面经过盐雾腐蚀后主要形成具有优良耐腐蚀性的腐蚀产物Zn5(OH)8Cl2.H2O,Mg促进了腐蚀产物Zn(OH)2向Zn5(OH)8Cl2.H2O的转变,有利于镀层耐腐蚀性的提高。
The effect of Mg content on the microstructure and corrosion resistance of Zn-6% Al alloy coating was studied. The results show that the effect of Mg on the microstructure and corrosion resistance of the alloy coating is obvious. When the content of Mg is less than 3%, the corrosion resistance phase MgZn2 appears in the solidified microstructure as the Mg content increases, The formation of Zn / Al / MgZn2 ternary eutectic, and with the Mg content is more uniform and dense, corrosion resistance of the coating continues to increase; when the Mg content reaches 3%, the best corrosion resistance of the coating; Mg addition After more than 4%, the coating corrosion resistance decreased, further addition of Mg coating will appear quality defects such as leakage plating. The results of XRD showed that the corrosion resistance of the coating on the surface of the Mg-containing coating was mainly caused by the corrosion of salt Zn5 (OH) 8Cl2.H2O and Mg, which promoted the corrosion of Zn (OH) 2 to Zn5 (OH) 8Cl2.H2O Change, is conducive to the improvement of coating corrosion resistance.