循环盐雾中两种聚氨酯涂层冷轧板腐蚀行为

Corrosion Behavior of Two Kinds of Polyurethane Coated Cold Colled Plates in Cyclic Salt Spray Test

为了解决冷轧板耐蚀性差的问题,常在其表面制备聚氨酯涂层。本文以电泳聚氨脂涂层冷轧板(ESPCC)和粉末喷涂聚氨脂涂层冷轧板(PSPCC)为研究对象,进行42 d的循环盐雾试验后,通过扫描电镜、X射线衍射分析和电化学测试来考察其在循环盐雾试验环境中的腐蚀形貌、腐蚀产物组成和电化学行为。结果表明,ESPCC和PSPCC经过42 d循环盐雾腐蚀后的单边扩蚀宽度分别为0.45 mm和0.25 mm。ESPCC比PSPCC的腐蚀颗粒更大,二者的腐蚀产物都是Fe_(3)O_(4)、α-FeOOH、γ-FeOOH和β-FeOOH,但是ESPCC的腐蚀产物的峰值强度高于PSPCC。ESPCC的腐蚀电流密度最大为1.08×10^(-5)A·cm^(-2),大于PSPCC的最大腐蚀电流密度1.34×10^(-9)A·cm^(-2);且其腐蚀42 d后电荷转移电阻只有2.88×10^(4)Ω∙cm^(2),小于PSPCC腐蚀42 d后的电荷转移电阻1.35×10^(10)Ω∙cm^(2)。

In order to solve the problem of poor corrosion resisitance of cold rolled plate,the polyurethane coating is often prepared on the surface.In this paper,the cold rolled plate with electrophoresis polyurethane coating(ESPCC)and the cold rolled plate with powder spraying polyurethane coating(PSPCC)were used as research objects.After 42 days of cyclic salt spray test,the corrosion morphology,corrosion product composition and electrochemical behavior in cyclic salt spray test environment were investigated by scanning electron microscope,X-ray diffraction and electrochemical test.The results show that the single side erosion width of ESPCC and PSPCC after 42 d cyclic salt spray corrosion is 0.45 mm and 0.25 mm,respectively.ESPCC has larger corrosion particles than PSPCC.The corrosion products of both are Fe_(3)O_(4),α-FeOOH,γ-FeOOH andβ-FeOOH,but the peak strength of the corrosion products of ESPCC is higher than that of PSPCC.The maximum corrosion current density of ESPCC reached 1.08×10^(-5)A·cm^(-2),which is greater than 1.34×10^(-9)A·cm^(-2) of PSPCC.The charge transfer re-sistance of PSPCC is only 2.88×10^(4) Ω∙cm^(2),which is less than 1.35×10^(10)Ω∙cm^(2) of ESPCC after 42 d cyclic salt spray corrosion.