阳极氧化二氧化钛纳米管涂层地热水腐蚀和沉积特性

拟采用金属二次阳极氧化等表面工程技术抑制地热水的腐蚀和结垢现象。在纯钛和钛合金(Ti-6Al-4V)板基底上采用二次阳极氧化法制备了二氧化钛微纳米管阵列涂层,探讨了制备工艺参数对涂层结构的影响,并进一步采用浸渍法对涂层进行了超疏水化处理。通过场发射环境扫描电镜表征了涂层的微观结构形貌。应用视频光学接触角测量仪检测了涂层表面的静态接触角,估算了表面自由能。对涂层的粗糙度也进行了测量。采用静态浸渍法评估了涂层的防垢性能。采用电化学线性极化曲线法研究了涂层在地热水中的耐腐蚀效果。结果表明,在钛及钛合金基底上,采用二次阳极氧化和浸渍工艺,可以制得具有规整二氧化钛微纳米管阵列结构和较低表面能的功能涂层;该涂层与基底相比,在地热水中的耐腐蚀性能得以提高;在碳酸钙饱和溶液中的污垢沉积速率降低约15%。同时,涂层与基底有较好的结合性能,疏水涂层经历多次胶带剥离和砂纸磨损实验后,依然保持着较高的疏水性。

Corrosion and deposition properties on anodization coatings of titanium dioxide nanotubes in geothermal water

In this paper, surface engineering technique of two-step anodization was used to solve the problems of corrosion and fouling in the geothermal water. TiO₂ nanotube layers were prepared on the substrates of pure titanium and its alloy (Ti-6Al-4V), and factors affecting layer structure were explored. Hydrophobization was further applied on the surface of TiO₂ coatings by immersion method. Microstructures of TiO₂ nanotubes were characterized by SEM. Static contact angle was obtained on the coatings via optical contact angle measuring device, and surface free energy was calculated. Roughness of the coatings was measured. Fouling property of coatings was investigated by static immersion experiments in CaCO₃ fouling solution. Corrosion property of coatings in geothermal water was investigated by potentiodynamic polarization curve. Well-aligned array of TiO₂ nanotubes and micro- and nano-scale coatings with low surface free energy were obtained on substrates of pure titanium and its alloy under optimal conditions of two-step anodization and immersion techniques. The TiO₂ coatings showed anticorrosion ability in geothermal water and antifouling property in saturated solution of CaCO₃. Compared with pure titanium and its alloy, fouling deposition rate decreased by 15% on the coatings. Meanwhile, the coatings displayed good mechanical durability through maintaining hydrophobicity after many times of tape-peeling and abrasion tests.