在冷轧钢板表面制备二乙烯三胺五甲叉膦酸-锌化学转化膜及其腐蚀防护性能的研究

本文通过调节二乙烯三胺五甲叉膦酸酯（DTPMPA）与Zn²⁺浓度以及溶液的pH值，将冷轧钢板浸泡于含有DTPMPA和Zn²⁺的混合溶液中即可在基体表面形成颜色均匀且具优异腐蚀防护性能的DTPMPA-Zn²⁺化学转化膜. 使用 SEM 和 EDS 研究了DTPMPA-Zn²⁺转化膜的表面形貌和元素组成，利用FTIR和XPS光谱方法探究了化学转化膜的表面官能团、化学组分及官能团与基底的结合方式，进而通过电化学阻抗谱（EIS）和极化曲线方法探究了DTPMPA浓度及成膜溶液pH值对化学转化膜的耐蚀性能的影响. 研究发现，DTPMPA与Zn²⁺共存时，二者发生螯合反应，并以Zn²⁺为交联剂通过多层组装在冷轧钢基体表面形成外观为蓝色的、厚度较为均匀的DTPMPA-Zn²⁺螯合物薄膜. 当成膜溶液的 pH=3.0、DTPMPA浓度为0.2%（除特别指出外，全文浓度均为质量百分数）、Zn²⁺浓度为0.044%时，化学转化膜展现出最优异的防腐性能，对基体的腐蚀保护效率可达91.6%.

Preparations and Corrosion Protection Investigations of Diethylene Triamine Penta(Methylene Phosphonic Acid)-Zn2+ Conversion Coatings on Cold Rolled Steel Substrates

Novel diethylene triamine penta(methylene phosphonic acid) (DTPMPA)-zinc ion (Zn²⁺) conversion coatings with uniform blue color and excellent corrosion protection were directly formed on the cold rolled steel (CRS) substrates by immersing a CRS plate into the film-forming solutions containing the appropriate concentrations of DTPMPA and Zn²⁺ ion at the proper pH. In this paper, surface morphologies and elemental compositions of DTPMPA-Zn²⁺ conversion coatings were characterized by SEM and EDS, respectivey. The surface functional groups, chemical constituents and binding modes to the substrates were investigated by means of FTIR and XPS methods. The influences of DTPMPA concentrations and pH values on the corrosion protection properties of the DTPMPA-Zn²⁺ conversion coatings were studied using electrochemical impedance spectroscopy (EIS) and polarization measurements. The results revealed that DTPMPA reacted with Zn²⁺ ions, forming the DTPMPA-Zn²⁺ chelate under the coexistence condition of both substances. Moreover, the chelate would be deposited onto the CRS substrate through the cross-linking of Zn²⁺ ions and form three-dimensional DTPMPA-Zn²⁺ thin films with uniform blue color and thickness. This kind of conversion coating exhibited the best corrosion resistance performance with the protection efficiency of 91.6% when the concentrations of DTPMPA and Zn²⁺ ion were 0.2wt% and 0.044wt%, respectively, in the film-forming solutions at pH = 3.0.