Electrochemical corrosion mechanism of titanium alloy in chemical equipment under influence of high temperature

doi:10.16265/j.cnki.issn 1003-3033.2021.01.014

Abstract

Abstract: In order to prevent corrosion accidents of equipment due to decrease in corrosion resistance of titanium materials after suffering from high temperature of a fire in chemical industry, corrosion behavior characteristics of titanium alloy TC4 after being treated by high temperature and different cooling methods, i.e., air cooling and water cooling, were studied through polarization curve and electrochemical impedance spectroscopy (EIS) by using electrochemical test technology. Then, a corresponding electrochemical corrosion model was constructed to explore relationship between characteristics of EIS and pore depth. The results show that TC4 sample can obtain the lowest corrosion current density after air cooling and water cooling treatment respectively at 1 050 and 910 ℃ with that of water cooling lower than air cooling. This means that when heating temperature is close to phase transition point temperature (about 1 000 ℃) of TC4, water cooling can make samples more resistant to corrosion than the other. Therefore, it proves to be a better cooling measure after titanium equipment is exposed to fire. In addition, based on results of scanning electron microscope, it is found that relationship between EIS characteristics and hole depth could reflect corrosion of TC4 more accurately. So the proposed model provides a theoretical basis for corrosion severity evaluation of titanium alloy equipment.

Key words: high temperature treatment, chemical equipment, titanium alloy, Ti-6Al-4V (TC4), electrochemical corrosion, cooling method

CLC Number:

X937

WANG Jinghong, MENG Qinglong, WANG Cangtian, ZHI Youran. Electrochemical corrosion mechanism of titanium alloy in chemical equipment under influence of high temperature[J]. China Safety Science Journal, 2021, 31(1): 95-101.

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