热镀锌无铬自润滑涂层及性能试验研究

Study on Performance of Chromium-free Self-lubricating Coating on Hot dip Galvanizing

目的改善热镀锌板成形条件,减少冲压成形工序。方法研发了一种热镀锌自润滑板,采用扫描电镜研究了热镀锌自润滑涂层的微观结构及成分,采用X射线荧光光谱仪测量了膜重。通过中性盐雾试验、摩擦系数测定、烘烤前后色差变化、涂敷凡士林后色差变化等方法,研究了涂层膜厚对耐蚀性、自润滑性、耐热性、耐指纹性、耐水性的影响,并得出最佳性能的膜层厚度控制范围。结果自润滑膜层为一种有机-无机混合的致密环保涂层,其在NSST/72 h条件下锈蚀面积小于5%,摩擦系数小于0.10,涂敷凡士林后色差变化值小于1,具有良好的自润滑性、耐蚀性、耐指纹性、耐水性等性能,满足用户的冲压成形条件。结论自润滑涂层的耐蚀性、耐热性、耐指纹性、耐水性等性能均已达到,甚至超越了现有无铬钝化的水平。涂层自润滑性、耐蚀性、耐指纹性随膜厚的增加而增强,耐热性随膜厚的增大而变差,膜厚对耐水性无明显影响。控制涂层膜厚为0.9~1.6 g/m^2,可确保涂层具有更加优良的稳定的自润滑性、耐蚀性和耐热性。

Objective To improve the forming performance of hot dip galvanized sheet, and reduce the stamping process. Methods A type of hot-dip galvanized self-lubricating steel was developed. The microstructure and composition of the coatings were studied by scanning electron microscope, and the weight of film was measured by X-ray fluorescence spectrometer. The effect of coating thickness on the corrosion resistance, self-lubricating, heat resistance, fingerprint resistance and water resistance were studied by the neutral salt spray test, friction coefficient test, and Color difference before and after baking. Meanwhile, the coating thickness control range for optimal performance was obtained. Results The self-lubricating coating was a compact and environmental protection film. The corrosion area of coatings was less than 5% after NSST/72 h, the friction coefficient was less than 0.10, and color difference was less than 1, so the coatings had good self-lubriciting, corrosion resistance, anti fingerprint resistance, water resistance and other properties, and it met the stamping forming conditions of the users. Conclusion The performance of the self-lubricating coating could reach or even exceed the level of Chromate-free passivation. As the coating thickness increased, the self-lubricating property, corrosion resistance, and fingerprint resistance of the coating were enhanced, the heat resistance was weakened, and the water resistance had no significant change. Controlling the thickness of coating between 0.9 and 1.6 g/m2 could ensure the stable and better performance of the coating in terms of self-lubricating ability, corrosion resistance and heat resistance.