碳钢在NaHCO3+NaCl溶液中的亚稳态孔蚀特征

用动电位极化和恒电位极化法研究了A3碳钢在不同浓度NaCl的0.5mol/LNaHCO₃溶液中亚稳态孔蚀行为。实验发现亚稳态电流波动峰具有快速上升、缓慢下降的特点。亚稳孔出现电位E_m 服从正态分布,随着Cl^-浓度的提高,E_m 值向负方向移动。亚稳孔的峰频变化规律与电位关系不大。恒电位极化时,当电位高于E_m而大大低于孔蚀电位E_b 时,电流波动保持一定时间后会最终消失,并产生直径为微米级的小蚀孔。当电位接近孔蚀电位时,一段时间的电流波动后电流往往迅速上升,最终转变为稳定蚀孔.     

两次动电位极化中316L不锈钢孔蚀参数的变化

以0.01 mol/L NaCl溶液中的316 L不锈钢为研究对象,采用慢速动电位扫描法研究了第一次极化只发生亚稳态孔蚀、同时发生亚稳态和稳态孔蚀两种条件对再次极化时小孔形核与生长的影响。结果表明,两种极化条件对不锈钢再次极化时的孔蚀行为的影响并不明显;两种极化条件下的第一次极化均导致材料表面活性点显著减少,从而再次极化后亚稳孔形核数目明显减少,同时亚稳态孔蚀电位和稳定孔蚀电位都有所升高;两种极化条件下的第二次极化过程中产生的亚稳态小孔的峰值电流和平均生长速度与初次极化相比有所增大,其原因主要是第二次极化的电位范围更高。     

溶液pH值对不锈钢亚稳态孔蚀行为的影响

用测试动电位的电流-时间曲线法研究了不锈钢在不同pH值的NaCl溶液中的亚稳态孔蚀行为.结果表明,随溶液pH值升高,316L不锈钢在NaCl溶液中的亚稳孔形核电位Em和孔蚀电位Eb均正移;不同NaCl浓度下,Em和Eb随溶液pH值的变化趋势基本一致.溶液pH值对亚稳孔形核数有明显影响,随pH值升高形核数降低.但pH值对亚稳态孔蚀过程的动力学参数,包括亚稳孔生长速度、峰值电流和平均寿命,均影响不大.     

表面粗糙度对非晶态合金亚稳态小孔形核和生长的影响

用恒电位和动电位极化法研究了表面粗糙度对非晶态ＮｉＣｒＦｅＳｉＢ合金亚稳态小孔形核和生长的影响，粗糙表面显著促进亚稳态小孔的形核，在恒电位下，亚稳小孔的生长电流随时间的平方线性增长为Ｉ－Ｉ０＝ｋ（ｔ－ｔ０）２．生长速度参数ｋ和亚稳态小孔的峰值电流都服从对数正态分布。在粗糙表面上亚稳态小孔的生长速度略高，且分布范围较大。     

两次动电位极化中316L不锈钢孔蚀参数的变化

以0.01mol/L NaCl溶液中的316L不锈钢为研究对象,采用慢速动电位扫描法研究了第一次极化只发生亚稳态孔蚀、同时发生亚稳态和稳态孔蚀两种条件对再次极化时小孔形核与生长的影响。结果表明,两种极化条件对不锈钢再次极化时的孔蚀行为的影响并不明显;两种极化条件下的第一次极化均导致材料表面活性点显著减少,从而再次极化后亚稳孔形核数目明显减少,同时亚稳态孔蚀电位和稳定孔蚀电位都有所升高;两种极化条件下的第二次极化过程中产生的亚稳态小孔的峰值电流和平均生长速度与初次极化相比有所增大,其原因主要是第二次极化的电位范围更高。     

铁在含Cl^—的NO3^——H2SO4体系中的钝化与孔蚀

用动电势扫描和交流阻抗方法研究纯铁在0.05mol/l H_2SO_4+0.1mol/l NaNO_3和0.05mol/lH_2SO_4+0.1mol/l NaNO_3+0.01mol/l NaCl溶液体系中的电化学行为。讨论了在酸性介质中,在阳极钝化的电势范围内,NO_3~-可抑制Cl~-对Fe表面的孔蚀作用;当[NO_3~-]》[Cl~-]时,在上述电势范围内Fe表面呈钝化态。     

稀土在含C1-介质中对铝合金孔蚀的缓蚀规律及机理研究

采用化学浸泡试验,动电位极化试验及俄歇电子能谱(AES)研究了14种三价稀土金属离子对LY12CZ铝合金在0.1mol.1-NaCI中性介质中孔蚀的缓蚀规律及机理,研究结果表明三价稀土金属离子缓蚀剂属于阴极沉淀型缓蚀剂,其缓蚀规律随原子序数的变化呈镧系‘四分组效应',其中Ce3+缓蚀性能最佳,铝合金表面的铈转化膜为多层结构.     

TiNiCu形状记忆合金在人工模拟体液中的电化学性能

采用电化学测试方法对TiNiCu形状记忆合金在Hank’s人工模拟体液中的电化学性能进行研究.结果表明,阳极极化时,在100~150 mV电位区间出现了活性溶解.随pH的降低和Cl-浓度升高,孔蚀电位Eb值负移,孔蚀敏感性增大,而温度对TiNiCu形状记忆合金的电化学性能影响不大.比较而言,在Hank’s人工模拟体液中,TiNiCu形状记忆合金的电化学性能比TiNi形状记忆合金劣,其原因可能是TiNiCu形状记忆合金在常温下的马氏体B19'可能掺杂着中间相B19,造成材料晶体结构不单一,易形成腐蚀原电池.此外,扫描电镜与X-射线分析表明,在晶界析出的Ti2Ni相及表面疏松的富Cu结构也促进了阳极活性溶解.     

稀土在含Cl~-介质中对铝合金孔蚀的缓蚀规律及机理研究

本文采用化学浸泡试验、动电位极化试验及俄歇电子能谱(AES)研究了14种三价稀土金属离子对LY12CZ铝合金在0.1mo1.1~-NaCl中性介质中孔蚀的缓蚀规律及机理。研究结果表明:三价稀土金属离子缓蚀剂属于阴极沉淀型缓蚀剂,其缓蚀规律随原子序数的变化呈镧系“四分组效应”,其中Ce~(3+)缓蚀性能最佳,铝合金表面的铈转化膜为多层结构。     

稀土在含C1-介质中对铝合金孔蚀的缓蚀规律及机理研究

采用化学浸泡试验 ,动电位极化试验及俄歇电子能谱 (AES)研究了 14种三价稀土金属离子对LY12CZ铝合金在 0 .1mo1.1—NaCI中性介质中孔蚀的缓蚀规律及机理 ,研究结果表明 :三价稀土金属离子缓蚀剂属于阴极沉淀型缓蚀剂 ,其缓蚀规律随原子序数的变化呈镧系‘四分组效应’ ,其中Ce3 缓蚀性能最佳 ,铝合金表面的铈转化膜为多层结构。     

Effect of hydrogen on the stress corrosion cracking behavior of X80 pipeline steel in Ku'erle soil simulated solution

Hydrogen was a key factor resulting in stress corrosion cracking (SCC) of X80 pipeline steel in Ku'erle soil simulated solution. In this article, the effect of hydrogen on the SCC susceptibility of X80 steel was investigated further by slow strain rate tensile test, the surface fractures were observed using scanning electron microscopy (SEM), and the fracture mechanism of SCC was discussed. The results indicate that hydrogen increases the SCC susceptibility. The SEM micrographs of hydrogen precharged samples presents a brittle quasi-cleavage feature, and pits facilitate the transgranular crack initiation. In the electrochemical impedance spectroscopy (EIS) measurement, the decreased polarization resistance and the pitting resistance of samples with hydrogen indicate that hydrogen increases the dissolution rate and deteriorates the pitting corrosion resistance. The potentiodynamic polarization curves present that hydrogen also accelerates the dissolution rate of the crack tip.     

Effects of cupric ions on the corrosion behavior of aluminum alloy 5A02 in ethylene glycol-water solution

The effects of cupric ions on the corrosion behavior of aluminum alloy 5A02 in ethylene glycol-water solutions were studied by potentiodynamic polarization, electrochemical noise (EN), and complementary techniques including scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). A positive corrosion potential and increased corrosion current were observed due to the deposition of copper. The results demonstrate that the main corrosion type was pitting and the increasing cupric ion concentration augmented the pitting density. The pits became larger and deeper as a result of the embedment of copper into the surface of the alloy. Cupric ions were preferentially deposited at the defects around the secondary phase, leading to the formation of Al-Cu microgalvanic couples, which increased the corrosion rate. The corrosion rate gradually reached a stable value as the concentration of cupric ions was increased beyond 10 mmol/L.     

Corrosion resistance of carbon ion-implanted M50NiL aerospace bearing steel

The effect of carbon implantation on the corrosion behavior of M50NiL aerospace bearing steel through surface modification was investigated. X-ray photoelectron spectroscopy, Auger electron spectroscopy and X-ray diffraction were used to analyze the composition and structure of the carbon-implanted layer. The corrosion properties of the untreated and carbon ion-implanted samples were evaluated by potentiodynamic curves and electrochemical impedance spectroscopy, which were carried out in 3.5% NaCl solution. Ion implantation of carbon in the M50NiL bearing steel yielded a distinct decrease of the corrosion current densities and an obvious increase of the polarization resistance. The experimental results indicated that the content of chromium oxide in the passive film increased with carbon implantation and that the intergranular corrosion was suppressed in the carbon-implanted sample. Better corrosion protection was observed in the carbon ion implantation sample.     

温度和Cl~-质量分数对304不锈钢耐点蚀性能的影响

采用线性极化技术和动电位循环伏安法2种电化学测试技术,研究温度和氯离子的质量分数对304不锈钢耐点蚀性能的影响,从而得到二者对点蚀的影响规律.结果表明:随着温度的升高和氯离子质量分数的增大,304不锈钢点蚀坑的孔径和数量均变大,电流密度也变大,击穿电位Eb负移,钝化区变窄,因此二者的升高使钝化膜的修复能力变差,点蚀敏感性增加.同时得到Eb与温度、Cl-质量分数都呈线性关系:温度每升高10℃,Eb向负方向移动约30 mV.Cl-质量分数每增加0.5%,Eb向负方向约移动10 mV.Eb-Ep随着温度或Cl-质量分数的升高而变大,但其与温度或Cl-质量分数并不成线性关系.     

SO2-4对含Cl-溶液中316 L奥氏体不锈钢钝化行为及点蚀行为的影响

利用动电位极化、电化学阻抗、恒电位极化以及恒电流极化等电化学测试手段,并结合扫描电镜进行点蚀形态观察,探究了含Cl-溶液中SO2-4浓度对316L奥氏体不锈钢的钝化行为及点蚀行为的影响.结果表明,含Cl-溶液中SO2-4的加入能够使316L不锈钢钝化区变宽,使点蚀电位变正,维钝电流密度降低,进而提高316L的耐点蚀能力.但是在点蚀发生后,随着SO2-4浓度的升高,点蚀内部和边缘形态表现出更为复杂的趋势,蚀坑的周长面积比明显增大.     

化学-力学耦合作用下混凝土内钢筋蚀坑的演化及分布规律

基于概率与统计知识,对化学-力学耦合作用下钢筋蚀坑的演化及其分布进行研究.结果表明氯盐侵蚀下钢筋蚀坑的演化可分为3个阶段:微观非稳态点蚀形核、细观亚稳态蚀坑、宏观稳态蚀坑.单一氯盐腐蚀作用下形成的宏观稳态蚀坑深度相对较小,而拉应力的引入将加剧钢筋表面化学/物理性质的不均匀,从而导致宏观稳态蚀坑深度较大.在氯盐及其与拉应...