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利用挂片实验研究了6种可溶盐对涂层下Zn腐蚀和涂层失效 的影响.发现对Zn基体来说NaCl对腐蚀的促进作用小于Na2SO4，接近于Na2SO3和FeS O4.NaNO3只对涂层起泡有较大促进作用，对腐蚀的影响较小.而ZnCl2无论对腐蚀还是 涂层起泡都无不良影响，甚至有一定的抑制腐蚀的作用.聚氨酯涂层的保护作用好于醇酸涂 层.傅利叶变换红外光谱(FTIR)分析表明水分子和涂层分子的羰基〖JG(〗C〖ZJLX，Y〗O 〖JG)〗形成氢键，因此水的渗透扩散比氧快得多.

Effect of 6 soluble salts on under film corrosion of metal and failure of the coatings were studied by means of exposed samples.The results show that the acceleration of NaCl to corrosion of zinc substrate is les s than that of Na2SO4 and similar with that of Na2SO3 and FeSO4.NaNO 3 acceleates greatly blistering of the coatings and affects relatively less the corrosion of the substrate.ZnCl2,however,has no harmful effects either on corr o sion of the zinc substrate or on failure of the coatings,and even has some inhib iting effect on corrosion of the substrate.The reason may be that the corrosion product when there is ZnCl2 is unsoluble Zn5(OH)8Cl2.The order that solu ble salts accelerate underfilm corrosion is as:Na2SO4≈Na2SO3＞NaCl≈FeS O4＞NaNO3ZnCl2;while the order of accelerating blistering is as:NaNO3 ≈Na2SO4＞ NaCl＞FeSO4≈Na2SO3ZnCl2.Polyurethane coating provides better pro tection than alkyd coating.Because the polarity of the molecule of polyurethane is greater than that of alkyd,the polyurethane coating can provide greater resis tance to O2 than alkyd coating.FTIR analysis shows that H-bond is formed betwe en the water molecule and the C=O group of the coatings,and therefore the water can permeate through the coatings much faster than O2.There is intermolecular H-bond 〖JG(〗O〖ZJZ；Y〗C〖ZJLX，S〗〖SX(B-*9〗H〖〗O〖DD(〗··〖DD)〗〖SX) 〗〖ZJS〗N〖ZJZ；Y〗C〖ZJLX，X；Y〗〖SX(B-*9〗O〖〗H〖DD(〗·· 〖DD)〗〖SX)〗〖ZJX〗N〖ZJZ；Y〗O〖ZJY〗〖JG)〗 in the structure of polyurethane,so the available sites for the water mol lcules to react is less than in alkyd coating.Therefore the capacity of polyu rethane to resist water is better than that of alkyd.