Hot-dip galvanized coating is proved to be effective in preventing chloride ion induced corrosion on steel bars, however, highly-toxic substances generated during the plating process seriously pollute the surrounding environment. Cold-sprayed zinc as an environment-friendly technology is an alternative to the hot-dip galvanized technology, but it has not been applied to steel bars in the alkaline environment of concrete. This study first fabricated the cold-sprayed zinc-coated steel bars, and then investigated the influences of Ca concentration and pH on the passivation of zinc-coated steel bars in the simulated concrete pore solutions through electrochemical tests, microstructure examination, and element composition analysis. The experimental results show that passive film can be generated on the surface of cold-sprayed zinc-coated specimens in the simulated concrete pore solutions with pH = 12.5 and Ca concentration above 0.8 g/L, but Ca concentration determines the density and quality of the passive film. The passive film can resist the attack of chloride ions up to 0.2 mol/L. Compared with hot-dip galvanized coating, more large-sized and compacted crystals are generated on the surface of cold-sprayed zinc coating. Thus, it is feasible to apply cold-sprayed zinc technology to provide corrosion protection for steel bars in the concrete.

中文翻译：

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冷喷涂镀锌钢筋在模拟混凝土孔隙溶液中的钝化

热镀锌涂层被证明可以有效防止氯离子引起的钢筋腐蚀，但电镀过程中产生的剧毒物质严重污染周围环境。冷喷锌作为一种环保技术，是热镀锌技术的替代品，但尚未应用于混凝土碱性环境下的钢筋。本研究首先制备了冷喷涂镀锌钢筋，然后通过电化学测试、微观结构检查和元素成分分析，研究了模拟混凝土孔隙溶液中Ca浓度和pH值对镀锌钢筋钝化的影响。实验结果表明，在pH=12.5、Ca浓度在0.8 g/L以上的模拟混凝土孔隙溶液中，冷喷镀锌试件表面可生成钝化膜，但Ca浓度决定了其密度和质量。被动膜。钝化膜能抵抗高达0.2mol/L的氯离子的攻击。与热镀锌层相比，冷喷锌层表面生成的晶体尺寸更大、更致密。因此，应用冷喷锌技术对混凝土中的钢筋进行腐蚀防护是可行的。