【摘要】 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Na2 SO4,接近于Na2 SO3 和FeSO4.NaNO3 只对涂层起泡有较大促进作用 ,对腐蚀的影响较小 .而ZnCl2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CO形成氢键 ,因此水的渗透扩散比氧快得多 .更多还原

【Abstract】 Effect of 6 soluble salts on underfilm 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 less 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 corrosion of the zinc substrate or on failure of the coatings,and even has some inhibiting 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 soluble salts accelerate underfilm corrosion is as:Na 2SO 4≈Na 2SO 3>NaCl≈FeSO 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 protection than alkyd coating.Because the polarity of the molecule of polyurethane is greater than that of alkyd,the polyurethane coating can provide greater resistance to O 2 than alkyd coating.FTIR analysis shows that H-bond is formed between 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 O C HO·· N C OH·· N O in the structure of polyurethane,so the available sites for the water mollcules to react is less than in alkyd coating.Therefore the capacity of polyurethane to resist water is better than that of alkyd.更多还原