热等静压处理对Zn-Al-Si合金涂层耐蚀性能的影响

摘要

对电弧喷涂 Zn-Al-Si 合金涂层进行热等静压(HIP)处理，通过电化学测试、盐水(3.5%NaCl，质量分数)全浸实验、扫描电镜观察和能谱分析，研究热等静压处理对电弧喷涂Zn-Al-Si合金涂层耐蚀性能的影响。结果表明：300℃、1 h、150 MPa HIP处理能大幅降低电弧喷涂Zn-Al-Si合金涂层的腐蚀电流，促进钝化现象的产生，提高耐腐蚀性能和防护寿命。HIP处理改善了涂层表面不平整结构、促进了表面元素分布；基本消除了涂层孔隙结构，孔隙率降低了87.15%，避免闭塞电池腐蚀的发生和涂层内部孔隙拓展延伸。经 HIP 处理后，涂层元素的均匀分布、平整的表面结构和致密的内部组织是降低腐蚀电流及产生钝化现象的主要原因。%The influence of hot isostatic pressing (HIP) on the corrosion resistance of arc spraying Zn-Al-Si alloy coating was studied by electrochemical test, salt solution (3.5%NaCl, mass fraction) immersion test, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results indicate that when the alloy is HIP-processed at 150 MPa and 300℃for 1 h, the corrosion current of arc spraying Zn-Al-Si coating is greatly reduced, the passivation phenomenon is promoted, and the corrosion resistance and protective life are improved. HIP treatment flats the surface, improves the element distribution, greatly eliminates the pore structure. The porosity is decreased by 87.15%, occluded cell corrosion and pore extension are avoided. Uniform element distribution, flat surface structure and dense internal tissue are the main reasons to cause the reduction of corrosion current and passivation phenomenon.