共查询到19条相似文献,搜索用时 46 毫秒
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目的研究NiAl复合涂层在腐蚀环境下的腐蚀行为及其失效机理,为其在工程中的实际应用提供理论依据。方法采用超音速电弧喷涂技术在20#钢基体表面制备了NiAl复合涂层,在此基础上对涂层的组织结构进行了表征,并对涂层与基体在3.5%NaCl溶液中的极化行为和交流阻抗谱行为进行了对比研究。结果 NiAl复合涂层的表层主要由Ni固溶体、NiAl金属间化合物和少量通过孔隙扩散到表层的Al组成。涂层呈典型的层状结构,结合较致密,表层(Ni)的孔隙率为5.3%,底层(Al)的孔隙率为4.4%。NiAl复合涂层的自腐蚀电位低于基体的自腐蚀电位,能起到良好的阴极保护效果。在测试初期,由于涂层厚度高达380μm,腐蚀介质通过涂层中存在的微裂纹和孔隙进入涂层内部,涂层快速消耗,形成较少的不溶性腐蚀产物,涂层阻抗较小,腐蚀速率较快。随腐蚀时间延长,不溶性腐蚀产物逐渐在孔隙内堆积,涂层内的极化电阻迅速增大,起到延缓腐蚀的作用。结论 NiAl复合涂层更好地发挥了Ni的耐蚀作用和Al的钝化保护作用,结合了两者的长处,表现出更好的耐蚀性能。涂层的自封闭作用是涂层阻抗值增加的主要原因。 相似文献
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电弧喷涂含非晶相的Fe基涂层的电化学行为 总被引:9,自引:0,他引:9
采用高速电弧喷涂技术制备了含有非晶相的3种铁基涂层(AC1-Fe59.5Cr16.2WC3.0Mn0.3 B20.2Si0.6,AC2-Fe59.8Cr16.0WC1.5Mo1.5Mn0.3B20.0Si0.7,AC3-Fe59.9Cr16.0Sn3.0Mn0.3B20.0C0.2Si0.6).对涂层的极化行为和交流阻抗行为进行了研究,涂层AC1中含有较多的非晶相,在Tafel线性极化区具有最低的自腐蚀电流,在阳极极化时表现出钝化趋势.涂层的电化学阻抗谱均可采用R(Q(R(QR)))型等效电路来进行分析,涂层AC1与其它涂层相比具有更大的电化学反应电阻.在一系列的电化学反应实验中,涂层AC1的耐蚀性最好. 相似文献
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目的探究高速电弧喷涂铝涂层在深水压力环境下的腐蚀行为。方法利用电化学阻抗谱、扫描电镜微观形貌观察、物相衍射和红外光谱等锈层分析手段,分析高速电弧喷涂铝涂层在不同实验条件下的腐蚀行为,并对实验结果进行了对比研究。结果 3 MPa高压浸泡72 h的铝涂层表面腐蚀产物呈现疏松粉状,并出现了腐蚀坑洞,铝涂层快速失效。常压浸泡72 h后的铝涂层表面腐蚀较轻,常压浸泡720 h后的铝涂层表面则已被腐蚀产物完全覆盖。经XRD分析,三种条件下的铝涂层腐蚀产物基本一致。进一步利用傅里叶变换红外光谱(FTIR)分析可知,3 MPa高压条件下,压力加速了碱式氯化铝水合物Al9Cl6(OH)21·18H_2O、Al5Cl3(OH)12·4H_2O等腐蚀产物的形成。这些腐蚀产物在高压下不能有效结合,且易于流失,致使涂层耐蚀性能快速下降。结论铝涂层在高压条件下形成的腐蚀产物不能有效覆盖在涂层表面阻止腐蚀介质侵入,导致铝涂层的耐蚀性能下降。 相似文献
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冷喷涂铝涂层在海水中的腐蚀行为研究 总被引:2,自引:0,他引:2
利用电化学测试手段研究冷喷涂铝涂层在海水环境中的腐蚀行为,并研究了冷喷涂铝涂层在中性盐雾中腐蚀速度的变化规律.结果表明,海水环境中冷喷涂铝涂层表面覆盖致密稳定的腐蚀产物,有效阻止了腐蚀介质向涂层内部的渗透,腐蚀速度随腐蚀时间的增加迅速降低. 相似文献
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Spontaneous electrochemical noise (EN) can be a rich source of information concerning the processes simultaneously occurring at a corroding interface. Potential noise fluctuations during the free corrosion of pure aluminum in different concentration of neutral sodium chloride solution are investigated, and the breakdown and restoration of passive metal's film are studied using potentiodynamic scanning (PDS) measurements and electrochemical impedance spectroscopy (EIS) technique. Two capacitance loops are observed in the Nyquist plots in two kinds of concentration, and the corrosion process is under activation control at first, then become diffusion control within the oxide film and corrosion products of (Al(OH)p-mCl-m) accumulated on the surface of the corroding electrode. It is suggested that the pitting corrosion is much easier to occur for pure aluminum in 7.0wt% than in 2.0wt% NaCl solution, and the high concentration of chloride ion in solution inhibits the repassivation of a metastable pit. The co 相似文献
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EVOLUTION OF THE ELECTROCHEMICAL CHARACTERISTICS DURING PITTING CORROSION OF PURE ALUMINUM IN SODIUM CHLORIDE SOLUTION 总被引:1,自引:0,他引:1
Z. Zhang C. Cai F.H. Cao Z.N. Gao J.Q. Zhang C.N. Cao 《金属学报(英文版)》2005,18(4):525-532
The corrosion behavior of pure aluminum in neutral 3.0% (mass fraction) sodium chloride (Na-Cl) solution has been studied using electrochemical impedance spectroscopy (EIS) measurement in conjunction with the scanning electron microscopy (SEM) technique. EIS information on the evolution of pitting corrosion over a period of 15 days has been obtained and analyzed with equivalent circuit technique. The results shown that, during the ensemble constant immersion time, two time constants involved, the high frequency one originated from the protective layer on the corroding surface while the low frequenO, one from the diffusion process or the corrosion reaction and so on. And there existed a period for oxide film to growth and thickening prior to the of the attacking of chloride ions to the substrate. Meanwhile, good relationship between EIS and the material corrosion type/severity has been obtained, which has been interpreted according to the characteristics of corrosion process such as auto acceleration of pitting corrosion and the protection of local anodic reaction to the area around them. 相似文献
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F.H. Cao Z. Zhang Y.L. Cheng J.F. Li J.Q. Zhang C.N.CaoDepartment of Chemistry Yuquan Campus Zhejiang University Hangzhou . ChinaState Key Laboratory for Corrosion Protection of Metals Institute of Metal Research The Chinese Academy of Sciences Shenyang China 《金属学报(英文版)》2003,16(4):319-326
The electrochemical features of commercial airfrarne material, Al alloy LY12, in 0.349mol/L neutral sodium chloride (NaCl) and sodium sulfate (NazSO^) solutions were investigated by electrochemical impedance spectroscopy (EIS) and potentiody-namic polarization techniques. The microstructure of the as-tested samples was studied by scanning electron microscopy. The results show that the Nyquist plots of LY12 at different immersion time displayed different features, indicating that the Cl- ions elevate the corrosion rate and inhibit the repassivation of a metastable pit. It also shows that the corrosion product of LY12 formed in SO42- solution isn't easy to dissolve, and it will cover the surface of working electrode in the electrolyte. SEM images indicate that the corrosion apparent area and pit number of LY12 in NaCl solution are greater than that in Na2SO4 solution. 相似文献
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用时域法EIS评估LY12CZ铝合金的膜下腐蚀 总被引:4,自引:1,他引:4
通过对表面带有硫酸阳极化膜和H06-1012H航空环氧底漆的LY12CZ铝合金型材进行剥蚀敏感性加速腐蚀试验(EXCO),采用时域法Laplace转换EIS和截面金相观察来衡量铝合金的膜下腐蚀,结果表明:时域法EIS测出的试样Rd、Cg能够评估膜下腐蚀的损伤程度;不同膜下腐蚀形态对应着不同的Rd、Cg的范围。Rd和Cg随腐蚀时间的变化趋势可以反映基体金属点蚀的萌生、漆膜鼓泡和基体出现剥蚀的历程,大量平行数据的统计分析表明:logRd符合Gumbel分布,logGg符合正态分布;由于logRd服从Gumbel分布,故可以根据小面积试样的logRd值,对大面积试样腐蚀最严重处的状况有所估计,大面积试样在EXCO溶液中浸泡时,其logRd随时间呈指数下降。 相似文献
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铝合金防护涂层老化动力学研究 总被引:3,自引:0,他引:3
在紫外/盐雾加速综合环境条件下,研究了铝合金试样上聚酰胺清漆老化过程。采用环境扫描电子显微镜观察了防护涂层表面形貌的变化,采用电化学阻抗(EIS)分析了涂层的老化过程,同时还测量了光泽度、颜色、表面电阻和体积电阻在涂层老化过程中的变化。结果表明:在涂层老化过程中,涂层孔隙率增加,而体积电阻、表面电阻则降低, EIS给出了在涂层老化的不同阶段的特征。采用光泽度、颜色、表面电阻和体积电阻以及电化学阻抗数据作为性能参数,建立了涂层老化动力学方程,并给出了涂层失效判据,并对涂层老化动力学的参数进行了讨论,认为采用体积电阻或低频阻抗模值作为性能参数描述涂层老化动力学过程更为合理。 相似文献
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用电化学阻抗谱(EIS)、扫描电子显微镜(SEM)和X射线能谱分析(EDAX)等检测技术,研究了LY12铝合金在周浸实验中的腐蚀行为及其机理。结果表明,LY12铝合金的腐蚀动力学符合幂函数规律。腐蚀历程为点蚀-晶间腐蚀-剥蚀(鼓泡)。EIS谱由高-中频容抗弧和低频收缩的感抗弧组成。 相似文献
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用电化学噪声表征7075铝合金的模拟大气腐蚀过程,旨在探索电化学噪声方法在航空器腐蚀检测上的应用.用吸附3.5%NaCl电解液的镜头纸紧贴于试样表面以模拟大气腐蚀环境,测试了7075T6铝合金的腐蚀电流、电位随浸泡时间的波动.电化学噪声实验结果显示,腐蚀初期电流波动幅度较小,正负方向幅度相当.腐蚀2h后;电流波动表现为正向锯齿波,幅度增大到0.3 μA左右;6h后电流表现为幅度不等的负向波动.可以预测2 h后铝合金钝化膜的破坏是腐蚀的主要过程,6h后钝化膜的修复则占主导地位. 相似文献