钛离子对无氰电镀镉耐蚀性能的影响

Effect of Titanium Ions on the Corrosion Resistance of Non-Cyanide Electroplated Cadmium

为了提高镉镀层的综合性能,通过在纯镉镀液中添加钛离子,利用电沉积法制备镀层,以提高无氰电镀镉镀层的致密性和耐蚀性能。用场发射扫描电子显微镜(FESEM)观察镀层表面及截面的微观形貌,并分析镀层内应力;用X射线衍射仪(XRD)分析镀层的相组成以及晶粒尺寸大小;用电化学工作站研究镀层的耐蚀性能。结果表明:在无氰镀镉镀液中加入钛离子后,镀层的晶粒尺寸从44.6 nm降低至16.5 nm;自腐蚀电位由-0.232 V升高到0.089 V;自腐蚀电流密度由3.56 m A/dm^(2)降低至2.58 m A/dm^(2);在5000 s内,纯镉镀层使渗氢电流密度降低至8.6μA/cm^(2),而加入钛离子后的镀层使渗氢电流密度降至3.2μA/cm^(2),降低速率远大于纯镉镀层。钛离子的引入使镀层结晶更加细致,增强了镀层的耐蚀性,提升了镀层对氢的阻挡能力。

For improving the comprehensive performance of the cadmium coating,titanium ions were added into the pure cadmium plating solu-tion,and the electrodeposition method was adopted to prepare the coating to improve the compactness and corrosion resistance of the non-cya-nide electroplated cadmium coating.Field emission electron scanning microscope(FESEM)was utilized to observe the surface and cross-sec-tional microstructure of the coating and analyze the internal stress of the coating.X-ray diffractometer(XRD)was employed to investigate the phase composition and grain size of the coating.Moreover,an electrochemical workstation was used to study the corrosion resistance of the coat-ing.Results showed that after adding titanium ions into the non-cyanide cadmium plating solution,the grain size of the coating decreased from 44.6 nm to 16.5 nm;the self-corrosion potential increased from-0.232 V to 0.089 V;the self-corrosion current density decreased from 3.56 m A/dm^(2)to 2.58 m A/dm^(2);within 5000 s,the hydrogen permeation current density decreased to 8.6μA/cm^(2)in case of a pure cadmium coating,while such value was only 3.2μA/cm^(2)in case of a cadmium coating containing titanium ions,which indicated a much larger reduction rate.In general,the addition of titanium ions made the crystallization of the coating more detailed,enhanced the corrosion resistance of the coating,and improved the hydrogen-blocking ability of the coating.