Q235、Q345R与304不锈钢在NaCl溶液中腐蚀声发射监测实验研究

应用声发射技术对Q235、Q345R和304不锈钢3种材料在NaCl溶液中的腐蚀过程进行了监测,获取了3种材料腐蚀过程中腐蚀产物的生成与剥落和气泡在材料表面的波动所导致的声发射信号。并应用声发射信号特征参量分析法和小波特征能谱系数分析方法,分析了3种材料在NaCl溶液中腐蚀产生的声发射信号的特征。     

304控氮不锈钢应力腐蚀过程中声发射信号聚类分析

研究了304控氮不锈钢试样在酸性氯化钠溶液中慢应变速率拉伸过程的声发射特征.采用基于自组织映射神经网络和K-均值聚类算法对长时间慢拉伸实验的声发射信号进行聚类分析,通过分析各类信号的持续时间、上升时间、振铃、能量、幅值、波形、频带能量等特征,从中找出了裂纹信号.将分类后的信号作为样本训练神经网络,对短时间慢拉伸实验检测...     

硫酸盐还原菌诱导腐蚀的电化学噪声分析

基于电化学噪声(EN)和信号处理研究硫酸盐还原菌(SRB)对304不锈钢诱导的腐蚀。将304不锈钢电极分别置于硫酸盐还原菌接种前后的培养基中,利用电化学工作站分别对2种试样的腐蚀进程进行电化学噪声测量,将测得的噪声数据去除直流漂移,再对这些数据进行时域、频域和小波分析。结果表明:通过时域分析得到的标准偏差和噪声电阻可表征腐蚀速率,局部因子则可以区分腐蚀类型。通过频域分析得到的功率谱密度曲线,能表征304不锈钢腐蚀的程度。小波分析则能从不同尺度下分解信号,更加直观、清晰地表征腐蚀进程。利用电化学噪声技术能很好地监测SRB对不锈钢的腐蚀影响,根据不同的需求采用不同的分析方法进行电化学噪声数据分析,才能准确表征腐蚀类型、腐蚀速率以及腐蚀程度。     

304不锈钢压力容器声发射检测试验研究

为了研究304不锈钢压力容器声发射特性,对含裂纹缺陷304不锈钢压力容器进行了声发射检测试验研究,通过参数和波形分析方法对声发射信号及缺陷定位情况进行了分析。研究结果表明304不锈钢容器裂纹扩展产生的声发射信号幅度较低,信号峰值频率主要分布在150KHz,缺陷定位不明显。研究结果对304不锈钢压力容器声发射现场检测具有一定参考意义。     

金属点蚀过程中声发射源机制研究

对Q235和不锈钢点蚀过程中的声发射信号特征进行实验研究。选取Q235腐蚀历程中的数据样本,对声发射信号进行了k均值聚类,区分噪声信号与腐蚀过程中的声源信号,得出了Q235腐蚀过程中声发射特性。     

敏化316L不锈钢晶间腐蚀的声发射特性

采用沸腾硝酸法和声发射技术研究了敏化316L奥氏体不锈钢的晶间腐蚀特性。通过失重法对3个周期实验的腐蚀速率进行计算和评定,并利用金相显微镜观察了各周期实验后试样腐蚀形貌;同时利用声发射检测系统实时采集了实验过程中的晶间腐蚀声发射信号,通过对信号进行参数分析和小波分析探究了敏化316L不锈钢晶间腐蚀的声发射信号特征与规律。实验结果表明,敏化316L不锈钢的晶间腐蚀分为腐蚀萌生阶段、平稳腐蚀阶段和快速腐蚀阶段;对信号进行参数分析发现各腐蚀阶段的计数率先缓慢增大继而保持平稳不变,最后又迅速增大;信号幅值出现明显的分层现象:腐蚀萌生阶段为25²7dB,平稳腐蚀阶段为2727dB,平稳腐蚀阶段为27³0dB,快速腐蚀阶段为3130dB,快速腐蚀阶段为31³4 dB;最后对信号进行小波分析发现声发射信号主要由频率为200、280kHz的信号组成。     

低碳钢腐蚀声发射检测实验研究

应用声发射技术,对低碳钢均匀腐蚀过程进行了检测,获取了低碳钢均匀腐蚀过程中的腐蚀声发射信号,并应用特征参量和小波包变换相结合的方法,分析了低碳钢腐蚀过程的声发射信号特性,同时结合储罐现场检测数据进行分析,对比实验条件下低碳钢腐蚀声发射信号与实际条件下储罐罐底腐蚀声发射信号的参数特征,其结果为低碳钢均匀腐蚀过程的声发射特征研究和储罐在线声发射检测提供了参考。     

Q235均匀腐蚀过程声发射监测实验研究

应用声发射技术分别对Q235均匀腐蚀过程中的气泡产生与金属溶解两个过程进行了监测,获取了Q235均匀腐蚀过程中的气泡产生与金属溶解声发射信号。并应用特征参量分析法,分析了气泡产生与金属溶解过程的声发射信号特性。研究发现应用能量、质心频率和峰值频率3种特征参量能准确区分两种不同的腐蚀信号。研究结果为Q235均匀腐蚀过程的声发射研究和噪声信号的分离提供了参考。     

304不锈钢上纳米TiO2涂层的制备与防腐蚀性能研究

采用溶胶–凝胶法和浸渍提拉法在304不锈钢上制备出均匀致密、彩色透明的纳米TiO2防腐蚀涂层。制备的最佳工艺条件是提拉4次,400°C热处理1h。在w(NaCl)=3%的NaCl溶液中的电化学测试表明,纳米TiO2/304不锈钢在有紫外光照射下其腐蚀电位低于304不锈钢基体。纳米TiO2涂层作为非牺牲性阳极对304不锈钢基体具有阴极保护作用和优异的防腐蚀性能。     

基于混沌理论的电化学噪声谱数据解析及其在局部腐蚀检测中的应用

将混沌理论引入电化学噪声（EN）谱的数据解析,对有机涂层失效过程和应力腐蚀过程的EN数据进行分析,采用关联维数表征局部腐蚀过程,取得了一些有意义的结果。分析了环氧酚醛/镀锡薄钢板失效过程的EN特征,通过计算涂覆镀锡薄钢板腐蚀过程的电化学电位噪声（EPN）谱特征,发现EPN对应的关联维数值随着局部腐蚀程度的加剧有增加的趋势。采用混沌相空间重构理论分析了304不锈钢应力腐蚀过程的电流噪声谱,利用关联维数表征应力腐蚀过程。数据计算结果表明应力腐蚀初期其相空间轨迹呈圆球形,应力腐蚀后期则变为椭圆形。研究结果表明,当裂纹萌生和扩展时,关联维数值增大,表明电化学噪声信号的不确定性与复杂性增加。     

304不锈钢应力腐蚀的临界氯离子浓度

通过慢拉伸实验得出了304不锈钢应力腐蚀敏感性与溶液中Cl-浓度的关系,用扫描电镜对拉伸试样的断口形貌进行了分析,得出了304不锈钢发生应力腐蚀的临界氯离子浓度。采用自行设计的装置对304不锈钢试样施加拉应力,通过恒应变条件下的电化学原位测试研究了304不锈钢钝化膜破裂电位与氯离子浓度的关系。得出导致钝化膜破裂电位突变的Cl-浓度与发生应力腐蚀破裂的临界Cl-浓度是基本一致的结论。     

The tribocorrosion behaviour of YSZ coating deposited on stainless steel substrate in 3.5 wt% NaCl solution

The YSZ coating was applied to 304 stainless steel substrate by atmospheric plasma spraying technology, and its electrochemical and tribological properties in 3.5 wt% NaCl solution were studied. In electrochemistry, under the action of cathode and anode potential, observe the changes of corrosion current density and EIS before and after wear. The results show that the YSZ coating has a very low corrosion current density during wear and corrosion compared to 304 stainless steel, and after the condition of the anode potential is applied, the effect of friction on the electrochemical impedance of the YSZ coating is very low, while the 304 stainless steel Impedance performance decreases; In terms of tribology, the friction coefficient of 304 stainless steel in 3.5 wt% NaCl solution is easily affected by potential, and the friction coefficient of YSZ coating relative to 304 stainless steel only changes under high potential. As the potential increases, the material volume loss of 304 stainless steel and YSZ coating increases linearly. From the data, the volume loss caused by the corrosion and wear of 304 stainless steel is much higher than that of YSZ coating.     

Investigations of the passive layer cracking by means of Dynamic Electrochemical Impedance Spectroscopy

The Dynamic Electrochemical Impedance Spectroscopy has been applied for stress corrosion cracking (SCC) investigations. The effect of applied potential and tensile stresses on the stress corrosion cracking behaviour of type 304L stainless steel (SS) immersed in 0.5 M NaCl solution of room temperature has been examined. This paper presents impedance spectra obtained for 304L stainless steel samples at the different potential values. The results obtained proved the possibility of providing new details about the dynamics of the initiation and propagation of the crack path compared to classical electrochemical techniques.     

Corrosion monitoring of type 304L stainless steel in nuclear near-high level waste by electrochemical noise

Electrochemical noise (EN) monitoring of 304L stainless steel (SS) and sensitized 304 SS in 3 N nitric acid and nuclear near-high level waste (HLW) solution was carried out using a three nominally identical electrode configuration under open circuit conditions. EN signals characteristics of passivation process was obtained for 304L SS in 3 N nitric acid throughout the measurement period, while in near-HLW solution, features of passivation and depassivation were observed. Potentiodynamic polarization of 304L SS in 3 N nitric acid and near-HLW showed spontaneous passivation. Noise resistance was evaluated from EN time record and this parameter was used in the present investigation to qualitatively assess the corrosion behavior during the immersion period. The average noise resistance was found to be lower in near-HLW solution when compared to 3 N nitric acid. The results of the investigation are presented in this article.     

PTA加氢反应器在碱洗条件下的安全分析

通过用SUS304L不锈钢制作的楔形张开加载预裂纹试样,在280℃、质量分数为3．0%的NaOH溶液的条件下进行应力腐蚀试验,以模拟对苯二甲酸(PTA)装置的加氢反应器PD-201不停车碱洗工作过程中SUS304L不锈钢在该介质环境下的抗应力腐蚀性能。结果表明：SUS304L不锈钢在此条件下经720h的浸泡,未发生应力腐蚀开裂现象,设备泵用SUS304L不锈钢作为内衬复合层是安全的。     

电解清除氧化皮的304不锈钢盘条耐蚀性的电化学评价

研究了电解清洗黑色和蓝黑色氧化皮304不锈钢盘条在盐酸和氯化钠介质中的耐蚀性能。动电位极化曲线方法测试了清洗后盘条的耐点蚀性能;恒电位充电曲线研究了不锈钢盘条的时间有效性。结果表明,电解清洗后不锈钢具有良好的耐蚀性。表面电子能谱测试表明清洗后不锈钢表面有显著的Mn元素富集,并探讨了Mn元素富集对耐蚀性的影响。     

Investigation of 304L stainless steel in a NaCl solution using a microcapillary electrochemical droplet cell: Comparison with conventional electrochemical techniques

In this work a comparison has been made between a localized (micro scale) and a conventional (large-scale) corrosion study of 304L stainless steel in a sodium chloride solution using Tafel plots and electrochemical impedance spectra. Results show the high ability of microelectrochemical techniques for the local investigation of corrosion procedures on solid surfaces, something which is not feasible with conventional large-scale techniques. In the second experiment the microelectrochemical behavior of a faulty copper layer on 304L stainless steel was investigated using linear sweep voltammetry. Glass capillaries touching only small areas of the surface were used and the copper coated surface of the steel sample was scanned in a 9 by 6 matrix (54 measurements) while acquiring data. The obtained corrosion potentials for both defect and intact areas were used to map the surface. The surface plot shows the exact position of the defect point in the coating layer.     

Pitting mechanism on an austenite stainless steel nanocrystalline coating investigated by electrochemical noise and in-situ AFM analysis

The pitting corrosion behavior of an austenite stainless steel with polycrystalline (PC) and nanocrystalline (NC) microstructure in 3.5% NaCl solution was investigated by electrochemical noise (EN) and in-situ atomic force microscopy (AFM) under anodic potential. The power spectral density (PSD) and wavelet transform have been employed to analyze the EN data. The pitting corrosion resistance of the NC coating was much higher than that of the PC alloy, with different pitting mechanisms observed for both specimens; a slow metastable pit generation and healing for the PC alloy and a fast metastable pit initiation and death for the NC coating. There was good conformity between the EN and the in-situ AFM analysis. The pitting corrosion mechanism has been discussed according to the EN analysis and the in-situ AFM observations.