摘要
目的获得绿色化、高稳定的碱性锌镍合金工艺,探索碱性代镉电镀锌镍工艺中单一组分参数对锌镍合金镀层性能的影响。方法在镍离子主络合剂C的碱性镀液中电沉积制备锌镍合金镀层。通过Hull Cell实验分析、电化学分析、扫描电镜分析等方法,研究碱性锌镍合金体系中,其他条件一定时,镀液中锌离子、镍离子、络合剂C以及氢氧化钠含量分别对镀层厚度、镍含量、耐蚀性和微观结构的影响。结果实验结果表明,其他条件一定时,镀层镍含量与镀液中镍离子和络合剂C含量成正比,与锌离子和氢氧化钠含量成反比,镀层中镍含量远低于锌含量,在该碱性锌镍工艺体系中表现为异常共沉积;扫描电镜结果和电化学测试结果表明,其他条件一定时,当镍离子和络合剂C含量增加时,镀层的腐蚀电流密度减小,且腐蚀电流密度的最大值和最小值相差1个数量级,镀层越致密,表面形貌越好,锌离子含量和氢氧化钠含量增加时,镀层表面粗糙,结构疏松,其腐蚀电流密度增大,耐蚀性降低。结论在络合剂C的碱性锌镍工艺中,电沉积锌镍合金是一个异常共沉积的过程,在电流密度为1~5 A/dm2时镀层镍含量较稳定,镀液金属离子(锌、镍离子)变化对镀层镍含量的影响较大,控制镀液中锌镍离子含量,镀层镍含量可稳定在12%~15%(质量分数)。镀液中各组分单一浓度变化,使镀层镍含量、形貌发生变化,对镀层耐蚀性产生影响。当其他条件一定时,镀液镍离子﹑锌离子﹑络合剂C和氢氧化钠含量分别为1.6 g/L、7 g/L、140 mL/L、80 g/L,镀层表面较平整,孔洞和裂纹较少,镀层的耐蚀性最好。
The Zn-Ni alloy process is an ideal protection technology for high-strength steel used in aviation field,and the Zn-Ni alloy coating has the characteristics of good corrosion resistance and low hydrogen embrittlement.However,in the Zn-Ni alloy process,the change of coordination agent concentration and solution service life have a great effect on the change of metal ion concentration and proportion in the plating solution during the actual deposition process,and the metal ion concentration and proportion of the plating solution have a great impact on the performance of the plating layer.In this experiment,the work aims to study the effect of a single parameter in an alkaline Zn-Ni alloy solution with complexing agent C as the main complexing agent for nickel ions on the performance of Zn-Ni alloy coatings prepared by electrodeposition on Q235 steel.Q235 steel of 20 cm×10 cm×1 mm(Hull Cell test)or 50 mm×100 mm×1 mm was used as the cathode,and then pre-treated,and nickel plate was used as the anode.When the cathode current density was 5 A/dm2 and the temperature was 25℃,the nickel ion content in the plating solution was between 1-2 g/L,the zinc ion content in the plating solution was between 6-10 g/L,and the complexing agent C content in the plating solution was between 60-160 mL/L.The sodium hydroxide content in the plating solution was between 80-160 g/L,and four groups of Zn-Ni alloy coatings under different conditions were prepared by electrodeposition on Q235 steel under control of single parameter changes.Then,the thickness and nickel content of the coatings were analyzed by X-ray fluorescence thickness gauge(BA-100),the electrochemical impedance and Tafel curve were determined by an electrochemical workstation(PARSTAT2273),the corrosion resistance of the Zn-Ni alloy coatings was characterized by the self-corrosion current density and charge transfer resistance,and the microscopic morphology of the Zn-Ni alloy coatings was observed by scanning electron microscope(JSM-6510LV).The experimental results showed that under other conditions,the nickel content of the coatings was directly proportional to the nickel ions and complexing agent C content in the plating solution,and inversely proportional to the zinc ions and sodium hydroxide content,and the nickel content in the coatings was much lower than the zinc content,which was an abnormal co-deposition in the alkaline Zn-Ni process system.The results of scanning electron microscopy and electrochemical test showed that when other conditions were constant,as the content of nickel ions and complexant C increased,the corrosion current density of the coating decreased,and the maximum and minimum values of the corrosion current density differed by an order of magnitude.In summary,in the alkaline Zn-Ni process of complexing agent C,the nickel content of the coating is relatively stable.The change of metal ions(zinc and nickel ions)in the plating solution has a great effect on the nickel content of the plating layer.When other conditions are constant,the nickel content of the plating layer can be stable at 12wt.%-15wt.%with the contents of nickel ions,zinc ions,complexing agent C and sodium hydroxide in the plating solution as 1-1.2 g/L,8-9 g/L,60-160 mL/L and 80-160 g/L respectively.The change of the single concentration of each component in the plating solution changes the nickel content and morphology of the coatings,which has an impact on the corrosion resistance of the coatings.When other conditions are constant,the content of nickel ions,zinc ions,complexing agent C and sodium hydroxide in the plating solution is 1.6 g/L,7 g/L,140 mL/L and 80 g/L,respectively,and the corrosion resistance of the plating layer is the best.The content of nickel ions,zinc ions,complexing agent C and sodium hydroxide in the plating solution will affect the nickel content in the plating layer to a certain extent,and then affect the microscopic morphology and corrosion resistance of the coatings.
作者
丁运虎
李雨昕
胡遐林
贺颖
刘宏芳
段海涛
DING Yunhu;LI Yuxin;HU Xialin;HE Ying;LIU Hongfang;DUAN Haitao(China Academy of Machinery Wuhan Research Institute of Materials Protection Co.,Ltd.,Wuhan 430030,China;School of Chemistry and Chemical Engineering,Huazhong University of Science and Technology,Wuhan 430074,China)
出处
《表面技术》
北大核心
2025年第4期130-142,共13页
Surface Technology
关键词
锌镍合金
碱性电镀
镀层厚度及镍含量
耐蚀性
微观形貌
Zn-Ni alloy
alkaline electroplating
coating thickness and nickel content
corrosion resistance
microstructure
