碳钢硅-锆复合预处理工艺研究

目的为解决传统预处理工艺能耗高、环境污染严重的问题,在前期研制的硅烷化和锆化配方的基础上,进一步调整工艺参数,探索将硅烷化和锆化工艺合二为一,优化出性能优良的硅-锆金属预处理工艺。方法通过硫酸铜点滴实验、盐水浸泡实验、电化学极化曲线法测试转化膜的耐蚀性能,采用拉开法测试涂层在金属表面的附着力。使用SEM对转化膜的微观形貌进行表征。结果硅锆处理的最佳工艺参数为:pH=3.5,处理温度20℃,处理时间10 min。极化曲线测试结果表明,经硅锆处理后的碳钢腐蚀电流密度为未处理的1/40,膜层耐蚀性能良好。拉开法测得涂层在基体上的附着力达到11.48 MPa,完全满足一般预处理工艺要求。微观形貌分析显示,硅锆膜属于纳米级无定形型转化膜,膜层均匀、致密,能为金属表面提供有效防护。结论通过调整工艺参数,将硅烷化处理和锆化处理合二为一,获得性能优良的硅-锆复合膜。转化膜的耐蚀性能优良,与涂层附着力良好,满足预处理工艺要求。

Process of Silane-Zirconium Pretreatment for Carbon Steel

The work aims to solve problems of high energy consumption and serious environmental pollution caused by conventional pretreatment process,develop a silane-zirconium metallic pretreatment process combining silanization and zirconium treatment and exhibiting excellent performing by further adjusting technological parameters based upon the silanized and zirconium-treated formula developed in early stage.Corrosion resistance of conversion films was tested by performing copper sulfate dropping experiment,saline immersion experiment and electrochemical polarization curve.Coating adhesion to metallic surface was tested by performing pull-off test,and microstructure of the conversion films was characterized with scanning electron microscope (SEM).The optimal process parameters were:pH=3.5,treatment temperature as 20 ℃ and treatment time as 10 min.Polarization curves results showed that corrosion current density of carbon steel treated with silane-zirconium was about 1/40 of that of untreated carbon steel.The films exhibited excellent corrosion resistance,coating adhesion to the substrate was approximately 11.48 MPa in the pull-off test,which completely met general requirement of pretreatment process.Microstructure analysis showed that the silane-zirconium films were nano-sized homogeneous,uniform and compact conversion ones which could provide effective protection for metallic surface.Silane-zirconium composite films exhibiting good properties can be prepared by adjusting pretreament technological parameters and combining silanization and zirconium treatment.The conversion films exhibit good corrosion resistance and adhesion to coatings,and meet requirement of pretreatment process.