Can the Prior Cathodic Polarisation Treatment Remove the Air-Formed Surface Film and Is It Necessary for the Potentiodynamic Polarisation Test?

Zheng-Rong Ye¹，Zhi-Chao Qiu¹，Zheng-Bin Wang²，Yu-Gui Zheng²，Ran Yi¹，Xiang Zhou¹

1. Research Institute of Petroleum Exploration and Development,PetroChina2. CAS Key Laboratory of Nuclear Materials and Safety Assessment,Institute of Metal Research,Chinese Academy of Sciences

摘 要：This paper clarifies two issues related to the prior cathodic polarisation treatment（PCPT） for the potentiodynamic polarisation test: whether PCPT can（1） remove the air-formed surface film and（2） affect the polarisation test results. X-ray photoelectron spectroscopy analyses of fluoride ion-labelled samples show that PCPT cannot remove the surface film completely due to the low reaction rate. Potentiodynamic polarisation tests demonstrate that PCPT with proper operating parameters,-1.0 V SCE for 5 min with subsequent open circuit potential（OCP） stabilisation in this study, is necessary because it can improve the test reproducibility without affecting the corrosion parameters by unifying the initial surface state. However, PCPT with lower potentials, longer time or no OCP stabilisation has significant effects on the electrochemical corrosion parameters due to the hydrogen absorption under the conditions of this study.

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