摘要
目的奥氏体不锈钢需要钝化处理以保证各种复杂工况下的长期耐蚀性,为了确保钝化效果,表面钝化质量检测成为不锈钢装备质检的关键环节,传统电化学检测方法存在耗时长、易受环境干扰的问题。提出了一种基于电位阶跃时域阻抗法的快速检测方法,用于评估316L不锈钢表面钝化质量。方法通过电位阶跃法,研究了不同钝化状态316L不锈钢的时域阻抗特性。对比分析了电位阶跃时间、数据平滑方法以及阶跃电位对时域阻抗谱的影响。同时,采用常规频域阻抗法进行对比验证,并通过动电位极化曲线测试分析了不同钝化状态下不锈钢的耐蚀性。结果滤波变窗平滑降噪法能够有效降低噪声干扰,获得的时域阻抗谱与频域阻抗谱高度一致,界面电荷转移阻抗值的误差在2%以内。当电位阶跃时间超过0.5 s时,阶跃时间对阻抗无明显影响;阶跃电位超过200mV时,会对不锈钢表面造成损伤。此外,随着钝化温度和时间增加,不锈钢的点蚀电位和阻抗值均显著提高,表明其耐蚀性得到改善。结论电位阶跃时域阻抗法结合滤波变窗平滑降噪处理,能够快速、准确地评估316L不锈钢表面钝化质量。该方法在0.5至1 s的阶跃时间和100mV的阶跃电位范围内,能够获得与频域阻抗谱高度一致的时域阻抗谱,适用于不锈钢表面钝化质量的快速检测。
Austenitic stainless steel is widely used in various fields such as petrochemical,aerospace,transportation,pharmaceuticals,and construction due to its excellent corrosion resistance.To maintain long-term corrosion resistance under diverse and challenging working conditions,the stainless steel requires passivation treatment.During the manufacturing of stainless steel equipment,verifying the quality of passivation is a critical link of quality control.Among the methods available,electrochemical detection offers high precision compared to visual or chemical methods.However,the electrochemical potential detection method tends to have a long testing time and is likely to be significantly affected by environmental factors,leading to considerable fluctuations in test results.To achieve rapid and accurate detection of surface passivation quality,the work aims to propose a new method of using potential step impedance in the time domain.The effects of potential step time,data smoothing techniques,and step potential on the time domain impedance spectrum were compared,with those observed in conventional frequency domain impedance analysis.316L stainless steel samples were treated by various passivation processes in nitric acid solutions at different temperatures(25℃and 45℃)for different time(10 and 30 minutes).The samples were prepared by cutting 2 mm thick stainless steel plates into 20 mm×20 mm specimens and then polished,cleaned,and passivated according to ASTM A380 standards.The electrochemical measurements were conducted through a three-electrode system with Ag/AgCl as the reference electrode and Pt as the counter electrode.The potentiostatic step-time domain impedance measurements were performed with step potentials ranging from 0 to 300 mV,and the current responses were recorded at a sampling frequency of 10 kHz for up to 2 seconds.The data were processed with various smoothing techniques,including adjacent averaging,FFT filtering,and the newly proposed filtering variable-window smoothing denoising method,which combined Savitzky-Golay polynomial fitting with FFT filtering and variable window-width smoothing.The results demonstrated that the filtering variable-window smoothing denoising method outperformed other techniques in preserving the transient peak and subsequent current characteristics,yielding time-domain impedance spectra that matched the frequency-domain impedance spectra.The optimized measurement parameters resulted in an error of less than 2%in the interface charge transfer impedance values compared to frequency-domain impedance results.Further analysis of the polarization curves and time-domain impedance spectra revealed that the pitting potential increased with the increasing time-domain impedance values,indicating improved corrosion resistance.It was also found that increasing the passivation temperature and duration enhanced the surface impedance,with the highest impedance observed for samples passivated at 45℃for 30 minutes.The SEM images confirmed that step potentials above 200 mV caused electrochemical corrosion on the sample surfaces,with the severity of damage correlating with the passivation quality.The reliability of the proposed method was validated by comparing the time-domain impedance spectra with frequency-domain impedance spectra under different passivation states.The findings indicated that the filtering variable-window smoothing denoising method,combined with optimized measurement parameters,provided a robust and accurate approach for assessing the passivation quality of stainless steel surfaces.This method offers a significant advancement over traditional techniques by reducing measurement time and improving precision,making it suitable for industrial applications where rapid and reliable surface quality assessment is critical.
作者
李昊彬
蒋不凡
程从前
王祺博
张雪娜
张心怡
曹铁山
赵杰
LI Haobin;JIANG Bufan;CHENG Congqian;WANG Qibo;ZHANG Xuena;ZHANG Xinyi;CAO Tieshan;ZHAO Jie(School of Materials Science and Engineering,Dalian University of Technology,Liaoning Dalian 116024,China)
出处
《表面技术》
北大核心
2025年第18期46-53,共8页
Surface Technology
基金
河南省科技攻关项目(232102230043)。
关键词
不锈钢
电位阶跃法
时域阻抗
平滑降噪方法
钝化质量
stainless steel
potential step method
time-domain impedance
smooth denoising method
quality of passivation
