硅烷化、锆化、硅锆化预处理膜的性能对比

Comparative study on properties of silanization,zirconization,and silanization-zirconization composite pretreatment films

[目的]旨在为碳钢涂装开发性能优良的环保型预处理工艺。[方法]在Q235碳钢表面分别制备了硅烷化、锆化和硅锆化预处理膜,并通过中性盐雾试验、电化学测试、拉拔试验和微观形貌分析,考察了它们的性能。[结果]3种预处理工艺都有效提升了基材的耐蚀性,2 h中性盐雾试验后未处理的碳钢表面腐蚀严重,硅锆化处理的试样表面仅有不超过10%的面积被腐蚀。电化学极化曲线测量的结果显示,预处理后试样的腐蚀电位都正移了,硅锆化试样的腐蚀电流密度只是未处理试样的1/38。电化学阻抗谱测试结果表明预处理后基材的腐蚀反应阻力变大,锆化和硅锆化能令材料的表面粗糙度增大。环氧涂层在3种预处理Q235钢表面的附着力均超过10 MPa,完全符合一般涂装应用的要求。[结论]3种预处理工艺均能有效提升碳钢基体耐蚀性和涂层附着力,其中硅锆化处理的效果最好。

[Introduction]Environmentally friendly pretreatment processes with excellent performance are required for painting carbon steels.[Method]Q235 carbon steel was pretreated by silanization,zirconization,and silanization-zirconization composite processes,respectively.The properties of the pretreatment films were examined through neutral salt spray(NSS)test,electrochemical measurement,pull-off adhesion test,and micromorphology analysis.[Result]All of the pretreatment processes improved the corrosion resistance of the substrate.The surface of the untreated Q235 carbon steel was seriously corroded after 2-hour NSS test,and the corrosion area of the specimen pretreated by the composite process was not more than 10%.The results of electrochemical polarization curve measurement showed that the corrosion potentials of the pretreated specimens were shifted toward the positive direction.The corrosion current density of the specimen pretreated by the silanization-zirconization composite process was only 1/38 of that of the untreated one.The results of electrochemical impedance spectroscopy indicated that the corrosion reaction resistance of the substrate was increased after pretreatment,and the surface roughness of Q235 carbon steel was increased after both zirconization and silanization-zirconization composite pretreatment.The pull-off adhesion strength of the epoxy coatings sprayed on the three types of pretreatment films was higher than 10 MPa,meeting the general coating quality requirement.[Conclusion]All of the three pretreatment processes can improve the corrosion resistance of carbon steel substrates and the adhesion strength of the coatings sprayed on them,in which the silanization-zirconization composite process shows the best performance.