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| ANODIC POLARIZATION BEHAVIOUR OF TYPE 904L AUSTENITIC STAINLESS STEEL IN HOT CONCENTRATED PHOSPHORIC ACID SOLUTION |
| Zhou Qingchu; Cao Tieliang(Shanghai Institute of Metallurgy; Chinese Academy of Sciences)Ji Chengjian(Zhejiang Xin'anjian Chemical Industrial Groan Corporation Ltd.) |
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Abstract The anodic polarization behaviour of type 904L austenitic stainless steel in 85Wt% H3PO4 at 140℃ was investigated using polarization curves, anodic charge curves, potential decay curves and electrochemical impedance spectra. The anodic polarization curve was characterized by four potential regions, i.e. active dissolution (-0.186～-0.12V vs SCE) reginn, active-passive transition (-0.12-0.2V)region, steady-state passive (0.2-0.9V) region and transpassive (>0.9V) region. In the active-passive transition region, the high frequency hot of impedance was a caparitive loop, and the low frequency limit was a Warburg impedance which indicated diffusion control. In steady-state passive region, the complex impedance plane was a capacitive semicircle indicating that the passinging process was controlled by the growth and dissolution of the film. In this region, the resistance of passive film reached its maximum, and the dispersion coefficient and capacitance reaChed their minima, which demonstrated that the films formed had the best corrosion resistance, the highest density, the thickest layer, and the most homogeneous surface. In the transpassive region, the diameter of high frequency capacitive semicircle sharply reduced, which corresponded to the reduction of corrosion resistance of passive film due to its transpassive dissolution; two inductive semicircles were observed at low frequency range, which indicated the adsorption of anion on the electrode surface. It could be concluded from the results of anodic charge curves and potential decay curves that the passive films formed in the steady-state passive region were homogeneous, and their stability increased with the increase of their growth potentials. The authors also discussed the parameters of anodic protection for 904L in hot concentrated phosphoric acid solution, and suggested the best protection potential range was 0.3-0.8V. The lower the temperature of H3PO4, the better the effect of anodic protection.
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Received: 25 February 1995
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Cite this article:
Zhou Qingchu; Cao Tieliang(Shanghai Institute of Metallurgy; Chinese Academy of Sciences)Ji Chengjian(Zhejiang Xin'anjian Chemical Industrial Groan Corporation Ltd.). ANODIC POLARIZATION BEHAVIOUR OF TYPE 904L AUSTENITIC STAINLESS STEEL IN HOT CONCENTRATED PHOSPHORIC ACID SOLUTION. J Chin Soc Corr Pro, 1995, 15(1): 7-14.
URL:
https://www.jcscp.org/EN/ OR https://www.jcscp.org/EN/Y1995/V15/I1/7
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| 1HalldbookofCorrosionData,EditedbyBruceD．Craig,ASMInternational,1989．p4132SmithSN,DroffelaarHVan．Br．Corros．J,1991,26(4):2653SchillmollerCM．AlloySelectioninWetProcessPhosphoricAcidPlants,In:ProcessIndustriesCOrrooion-TheTheoryandPractice,MonizBJ．PollockWI．ed．NACE,1986．p1614中国科学院上海冶金研究所．热法磷酸生产中蒸发器的防蚀措施-可行性研究报告,19935BanksWP,fornchEC．MaterialsProtection,1967,6(6):486LinderB．IndustrialCorrosion,1987,5(3):127ZhouQingchu,XuNaixin,ShihShengtal．Corros．Sci,1991,32(10):11438周庆初,徐乃欣,石声泰．中国腐蚀与防护学报,1986,6(4):2609傅献彩,陈瑞华．物理化学(下册),高等教育出版社(1980) |
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