表面充氢对TA2在草酸溶液中腐蚀行为的影响

目的提高TA2在草酸溶液中的耐蚀性,揭示表面充氢提高钛在草酸溶液中耐腐蚀性能的机理。方法采用电化学充氢的方法对TA2试样进行表面充氢,采用SEM和XRD分析充氢对试样表面形貌和相组成的影响,并采用电化学测试和腐蚀浸泡实验研究不同充氢时间的TA2试样在草酸溶液中的耐蚀性。结果电化学充氢后,TA2试样表面会生成一层以Ti H1.5为主要组成相的氢化钛层,该氢化钛层的厚度随充氢时间的延长而增厚。电化学测试结果显示,随着充氢时间的延长,TA2试样在草酸溶液中的自腐蚀电位从–0.7 V(vs.SCE)逐渐增加到0 V左右,腐蚀倾向显著下降;极化电阻Rp则从0.2 kΩ·cm^2逐渐增加到了24.1 kΩ·cm^2,耐蚀性能增强。腐蚀浸泡实验结果表明,随着充氢时间的延长,TA2试样在草酸溶液中的腐蚀程度逐渐减弱,腐蚀速率也从未充氢时的4.63mm/a逐渐下降到0.03mm/a。结论在草酸溶液中,电化学充氢TA2试样表面生成的氢化钛层对Ti基体具有保护作用,并且保护效果随氢化钛层的增厚而增强。试样表面氢化钛层对Ti基体的保护作用除了与成分有关外,还与其结构相关,完整致密的氢化钛层可以对Ti基体起到很好的保护作用,而疏松多孔的氢化钛不仅不能保护Ti基体,反而还会促进Ti基体的腐蚀。

Corrosion Behaviors of TA2 in Oxalic Acid Solution after Surface Hydrogen Charging

The work aims to improve the corrosion resistance of TA2 in oxalic acid solution,reveal the mechanism of hydrogen charging to improve the corrosion resistance of titanium in oxalic acid solution.The surface of TA2 was hydrogenated by hydrogen charging.The effects of hydrogen charging on the surface morphology and phase composition of the sample were analyzed by SEM and XRD.Electrochemical tests and corrosion immersion experiments were carried out to study the corrosion resistance of TA2 samples with different hydrogen charging times in oxalic acid solution.After hydrogen charging,a layer of titanium hydride with TiH1.5 as the main component was formed on the surface of the TA2 sample.The thickness of the titanium hydride layer was thickened with the extension of hydrogen charging time.Electrochemical test results showed that with the extension of hydrogen charging time, the self-corrosion potential of TA2 sample in oxalic acid solution gradually increased from–0.7 V (vs. SCE) to about 0 V, and the corrosion tendency decreased remarkably;the polarization resistance Rp graduallyincreased from 0.2 kΩ·cm^2 to 24.1 kΩ·cm^2, and corrosion resistance was enhanced. The results of corrosion immersionexperiments showed that the corrosion degree of TA2 sample in oxalic acid solution gradually decreased with the extension ofhydrogen charging time, and the corrosion rate also gradually decreased from 4.63 mm/a to 0.03 mm/a. In the oxalic acidsolution, the titanium hydride layer formed on the surface of the TA2 sample after hydrogen charging has protective effect on thetitanium substrate, and the protective effect is enhanced with the thickening of the titanium hydride layer. The protective effectof titanium hydride layer of sample surface on titanium substrate on is related to its structure in addition to its composition: thecomplete and dense titanium hydride layer can protect the titanium substrate well;while the loose porous titanium hydride notonly cannot protect it, but also promotes the corrosion of titanium substrate.