Research on corrosion of TC4 titanium alloy in concentrated high-salt wastewater environment
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摘要: 从蒸汽机械压缩技术（MVR）腐蚀环境角度，模拟高盐废水浓缩液开展了TC4材料耐腐蚀性能研究，通过微观组织表征、腐蚀失重、缝隙腐蚀、电化学测试（开位电路、电化学阻抗以及动电位极化曲线测试）等腐蚀测试，证实了TC4合金的（α+β）双相钛合金，在各种高氯离子强度环境中的耐缝隙腐蚀能力较强，14 d全浸试验没有出现局部点蚀，最大腐蚀速率仅1 mg/(cm2·a)左右，远低于2205双相钢在相同环境下的腐蚀情况。电化学测试结果也表明：TC4钛合金在高氯离子强度溶液中，表面形成的惰性钝化层生成迅速并保持稳定，对抑制材料表面腐蚀、缝隙腐蚀也有较明显作用。TC4合金的高温耐腐蚀性能适用于高盐废水环境，在MVR技术处理高氯含量工业污水方面有潜在应用价值。Abstract: In this paper, the corrosion resistance of TC4 material was studied by simulating the concentrated solution of high salt wastewater from the perspective of mechanical vapor recompression (MVR) corrosion environment. The corrosion tests were carried out through microstructure characterization, corrosion weight loss, crevice corrosion, electrochemical test (open circuit, electrochemical impedance and potentiodynamic polarization curve test). The properties of TC4 alloy were confirmed (α+β) biphase titanium alloy has strong resistance to crevice corrosion in various high chloride ion environments. There is no local pitting corrosion in 14 day full immersion test, and the maximum corrosion rate is only 1 mg/(cm2·a). The results of electrochemical test also show that the inert passivation layer formed on the surface of TC4 titanium alloy in high chloride ion solution is generated rapidly and remains stable, which also plays an obvious role in inhibiting material surface corrosion and crevice corrosion. TC4 alloy has high temperature corrosion resistance and is suitable for high-salt wastewater environment. For MVR technology, it has potential application value in the treatment of industrial wastewater with high chlorine content.
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图 4 TC4失重量随腐蚀时间的变化关系
Figure 4. Relationship between weight loss and corrosion time of TC4
图 5 在酸性25.5%NaCl溶液中典型极化曲线
（Ecorr为自腐蚀电位，Icorr为自腐蚀电流，Epit为点蚀电位，Ep为回扫平衡电位）
Figure 5. Typical polarization curve in acidic 25.5% NaCl solution
图 6 TC4合金试样正面缝隙腐蚀情况
（从左至右分别为溶液1、溶液2、溶液3）
Figure 6. Front view of TC4 alloy after crevice corrosion
表 1 合金在不同浓度溶液中的全浸腐蚀速率
Table 1. Total immersion corrosion rate of alloys in different concentration solutions
mg/(cm2·a) 材料种类 腐蚀速率 溶液1 溶液2 溶液3 TC4合金 1.13±0.30 0.30±0.18 0.33±0.03 2205双相钢 8.33±3.59 3.18±1.68 3.70±0.35 
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表 2 电化学极化曲线分析结果
Table 2. Results of electrochemical polarization analysis
Ecorr/mV Icorr/(A·cm−2) Epit/mV Ep/mV 溶液1 −329 1.494 E-07 1600 0 溶液2 −318 1.468 E-07 1600 308 溶液3 −333 3.234 E-07 1400 −105
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