氯离子对6063铝合金铈-锰转化膜耐蚀性的影响

在Ce-Mn稀土钝化液中添加Cl-作为促进剂,以6063铝合金为基体制备了Ce-Mn转化膜。分别采用扫描电镜(SEM)和能谱仪(EDS)研究了转化膜的表面形貌及元素组成,并采用硫酸铜点滴腐蚀实验、动电位极化曲线以及电化学阻抗谱(EIS)研究了Ce-Mn转化膜的耐蚀性。结果表明,Ce-Mn转化膜主要由Ce、Mn、O等元素组成,往稀土钝化液中添加Cl-可使膜层更平整、致密,转化膜的平均耐点滴时间从50s提高至100s,在NaCl质量分数为3.5%的腐蚀介质中的腐蚀电流密度明显降低,转化膜极化电阻增大,铝合金的耐蚀性显著提高。     

Improved electrochemical performance of trivalent-chrome coating on Al 6063 alloy via urea and thiourea addition

This project aims at improving the electrochemical performance of trivalent-chrome coating through urea and thiourea addition. The electrochemical behaviors of coatings formed with different concentrations of urea and thiourea were investigated in 3.5 wt.% NaCl solution at 25 °C, using potentiodynamic polarization curves and EIS. The corrosion resistance of coatings is improved greatly by adding a small amount of inhibitors, whereas the excessive addition deteriorates the corrosion resistance. Thiourea addition presents better effect than urea. To explain the EIS results of the coatings, a simple equivalent circuit was designed. The EIS parameters were obtained by fitting the EIS plots. The results of the polarization curves and EIS show that the inhibitor-containing coatings present better corrosion resistance than the coating without inhibitor. The morphology and composition and valence state of the conversion coatings were examined by SEM and EDS and XPS, respectively. The results indicated that the trivalent chromium coating was developed on Al 6063 alloy, urea and thiourea inhibitors were also deposited on the substrates, respectively. A noticeable chemical shift was also observed.     

Surface protection of copper in aerated 3.5% sodium chloride solutions by 3-amino-5-mercapto-1,2,4-triazole as a copper corrosion inhibitor

Surface protection of copper in aerated 3.5% NaCl solutions by 3-amino-5-mercapto-1,2,4-triazole (AMTA) has been reported. The study has been carried out using weight loss, pH, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and chronoamperometric (CA) measurements along with scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) investigations. Weight-loss data indicated that the dissolution rate and the pH of the solution decreased to a minimum after 24 days of copper immersion due to the inhibitive action of AMTA. PDP, CA, and EIS measurements showed that AMTA decreased the corrosion rates and increased the polarization resistance and inhibition efficiency. This effect was increased with increasing AMTA concentration as well as the immersion time of the copper electrode to 50 h before measurements. SEM micrograph and EDS analysis proved that the inhibition of copper corrosion takes place due to adsorption of AMTA onto the surface. These results together confirmed that AMTA is a good mixed-type inhibitor and the inhibition of copper corrosion is achieved by strong adsorption of AMTA molecules.     

Investigation on corrosion and wear resistance of MgO-Al2O3 composite coating prepared by plasma electrolytic oxidation

Ceramic coatings were prepared on 6061 Al alloy in a mixed electrolyte with/without MgO powders at different treatment durations. The results of energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) showed that MgO powder was incorporated into the coatings, and Mg species gradually aggregated into coating inside as prolonging the oxidation time. Scanning electron microscopy (SEM) showed that MgO additive had a certain effect on the microstructures and coating thickness. The corrosion behavior tests evaluated by potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) in 3.5 wt% NaCl solution suggested that at the same treatment time, the addition of MgO powders can improve the corrosion resistance of the coating, and the Mg-rich layer can affect the corrosion resistance of the coating. The tests of mechanical properties showed that the addition of MgO powders improved the stability and hardness of the coating.     

Plant derived cationic dye as an effective corrosion inhibitor for 7075 aluminum alloy in 3.5% NaCl solution

The inhibition of the corrosion of 7075 aluminum alloy in 3.5 wt.% NaCl solution by 5,6-dihydro-9,10-dimethoxybenzo[g]-1,3-benzodioxolo[5,6-a]quinolizinium (berberine) has been studied using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electrochemical microscopy (SECM) and scanning electron microscopy (SEM). Inhibition efficiency was found to increase with increasing concentration of berberine. The adsorption of the berberine on the 7075 aluminum alloy surface obeyed the Langmuir adsorption isotherm. The adsorbed film on 7075 aluminum alloy surface containing inhibitor was confirmed by the SEM, and SECM. The results obtained showed that the berberine could serve as an effective inhibitor of the corrosion of 7075 aluminum alloy in 3.5% NaCl.     

[V10O28]6-柱撑纳米水滑石在AZ31镁合金有机防腐涂层中的应用

研制了一种以钒酸盐阴离子([V10O28]6-)柱撑纳米水滑石防腐颜料替代铬酸盐,用于AZ31镁合金腐蚀防护的有机涂层.研究了水滑石在不同浓度的NaCl溶液里的吸附和离子交换性能,以及钒酸盐缓蚀剂的极化曲线:考察了该水滑石防腐颜料的添加比例对镁合金环氧防腐涂层性能的影响,并通过电化学交流阻抗(EIS)测试技术对各试样进行了性能检测.结果表明,添加了20%(质量分数)水滑石的环氧涂层对镁合金具有较好的防腐作用.     

片状玻璃对水性复合锌铝合金涂层耐蚀性的影响

为了改善水性锌铝合金涂层的耐蚀性能,在硅烷钝化液中加入玻璃粉制备了玻璃/水性锌铝涂层,采用中性盐雾试验、电化学阻抗谱、极化曲线等方法研究了玻璃粉用量对 Q235 钢表面该涂层耐蚀性能的影响,利用扫描电镜、能谱、X 射线衍射等技术分析了涂层的形貌、组成以及元素分布状况。结果表明,添加片状玻璃粉可以提高涂层的耐蚀性能。玻璃粉与金属粉以平行叠加的方式排列在锌铝合金涂层中,部分玻璃粉包覆在涂层的外围形成致密的网状结构。当玻璃粉的添加量为 20 g/L时,涂层的耐蚀性能最好,耐中性盐雾试验时间为 3 100 h,是不添加玻璃粉涂层的 5 倍。     

An ecofriendly approach for corrosion control of 6061 Al-15％(v) SiC(p) composite and its base alloy

Corrosion inhibition characteristics of bio polymer dextran was studied for the corrosion control of 6061 Al-15%_((v)) SiC_((P)) composite and its base alloy in 1 mol·L~(-1) HCl. Standard electrochemical techniques such as potentiodynamic polarization(PDP) measurements and electrochemical impedance spectroscopy(EIS) method were adopted for corrosion rate measurement. Surface morphology was studied by scanning electron microscopy(SEM) and elemental mapping was done by energy dispersive X-ray(EDX) analysis. Suitable mechanism was proposed for corrosion and inhibition process. Results indicated that dextran acts as an excellent anticorrosive agent for the corrosion control of 6061 Al-15%_((v)) SiC_((P)) composite, with maximum inhibition efficiency of 91% for the concentration of 0.4 g·L~(-1) at 303 K. Dextran acted as a mixed type of inhibitor, and got physically adsorbed both on composite and base alloy by obeying Langmuir adsorption isotherm. Dextran is proved to be a green inhibitor with environmental and economic benefits.     

热浸Zn-0.05Al-0.2Sb合金镀层锌花耐蚀性研究

用金相显微观察、能谱分析(EDS).中性盐雾试验(NSS)和电化学阻抗谱(EIS)研究了热浸Zn-0.05Al-0.2Sb合金镀层表面的3种锌花:亮锌花,羽毛状锌花和暗锌花.结果表明,3种锌花表面都存在明显的Sb、Al偏析,按照亮锌花、羽毛状锌花和暗锌花的顺序,锌花的表面粗糙程度和表面Sb、Al偏析都依次增大,而耐盐雾腐蚀性能和EIS的低频阻抗依次降低.     

Corrosion protection behaviour of sol–gel derived N,N-dimethylthiourea doped 3-glycidoxypropyltrimethoxysilane on aluminium

The present work describes the anticorrosion features of inhibitor doped sol–gel coating on Al metal. Sol–gel coatings were prepared by using 3-glycidoxypropyltrimethoxysilane (GPTMS) as parent precursor. In order to improve the corrosion resistance property of coating, N,N-dimethylthiourea was added into the sol–gel matrix. The corrosion inhibitor doped sol–gel coating on metal was characterized by Fourier transform infrared analysis (FTIR) and scanning electron microscope (SEM). Inhibition effect of N,N-dimethylthiourea doped GPTMS coating on Al substrates in 1% NaCl solution was investigated using electrochemical impedance (EIS) and polarization studies. EIS results showed that the corrosion resistance of sol–gel coating significantly improved upon addition of N,N-dimethylthiourea. The study had outlined the nuances of doping an organic inhibitor to enhance the protection ability of sol–gel coating on Al metal.     

钼酸盐对镁合金在模拟冷却水中腐蚀的抑制作用

采用Tafel极化曲线、电化学阻抗谱方法研究了钼酸钠对AZ40镁合金在模拟冷却水中腐蚀的抑制作用,利用扫描电子显微镜(SEM)和能量色散谱(EDS)表征了试样的形貌及组成。结果表明,钼酸钠对镁合金在模拟冷却水中的腐蚀具有一定的抑制作用,钼酸钠浓度为1000 μg·g^-1时缓蚀效果最佳。钼酸钠的加入减弱了腐蚀性Cl^-在试样/介质界面的吸附,同时参与镁合金试样在模拟冷却水中表面膜的生成,使表面膜变得致密,从而较好地抑制镁合金的腐蚀;其缓蚀作用属于阳极抑制型缓蚀作用。     

Corrosion behavior of TiN and TiN/Ti composite films on Ti6Al4V alloy in Hank’s solution

Surface films of TiN and TiN/Ti were deposited on Ti6Al4V alloy by arc ion plating (AIP). Open-circuit potential, potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) were employed to investigate the corrosion performance of TiN and TiN/Ti films in Hank’s simulated body fluid at 37 °C and pH 7.4. Scanning electron microscopy (SEM) was used to study the surface morphology of the corroded samples after the potentiodynamic polarization tests. The results show that the TiN and the TiN/Ti films can provide effective protection for the Ti6Al4V substrate in Hank’s fluid, and the TiN/Ti composite film showed a corrosion resistance superior to that of the TiN film. The outer TiN layer of the composite film mainly acted as an efficient barrier to corrosion during short-term experiments. In contrast to the bare Ti6Al4V, no pitting was observed on the surface of the TiN and TiN/Ti films deposited on the bare alloy after potentiodynamic polarization.     

Inhibitive Behaviour of Zinc Gluconate on Aluminium Alloy in 3.5 % Nacl Solution

The present work investigates corrosion behaviour of aluminium alloy in 3.5 % sodium chloride medium at 28 °C in the absence and presence of 0.5, 1.0, 1.5 and 2.0 % g/v concentrations of zinc gluconate using gravimetric and electrochemical techniques. The aluminium alloy was cut to corrosion coupons, and immersed into 3.5 % sodium chloride solution containing different inhibitor concentrations (0.5, 1.0, 1.5 and 2.0 % g/v) within a period of twenty-eight days. The surface morphology of the metal was examined by high resolution scanning electron microscopy equipped with energy dispersive spectroscopy (HR-SEM/EDS). From the results, it was found that the adsorption of zinc gluconate reduced aluminium alloy corrosion in the sodium chloride medium. Experimental results also showed that inhibition efficiency increased with an increase in zinc gluconate concentration. Furthermore, potentiodynamic polarization results revealed decrease in corrosion rates (CR), corrosion current densities (Icorr), and increasing corrosion resistance (Rp) in the presence of zinc gluconate in 3.5 % NaCl solution. Tafel polarization analyses indicated that zinc gluconate is a mixed type inhibitor. The adsorption of zinc gluconate on the aluminium alloy surface followed Langmuir adsorption isotherm.     

Inhibition of CuNi10Fe corrosion in seawater by sodium-diethyl-dithiocarbamate: an electrochemical and analytical study

The efficiency of sodium-diethyl-dithiocarbamate (NaDDTC) as corrosion inhibitor for CuNi10Fe alloy was studied in natural seawater by means of immersion tests, polarization measurements, electrochemical impedance spectroscopy (EIS) and Auger electron spectroscopy (AES). After immersion of the alloy for 24 h in various concentrations of NaDDTC, layers were formed which act as a physical barrier to the corrosion attack. The polarization curves obtained with electrodes in seawater indicate retardation of both the anodic and cathodic processes. From EIS measurements equivalent circuits, which illustrate the behaviour of the reaction product film, were proposed and individual circuit elements at the open circuit potential and anodic polarization were defined. The results obtained for inhibitor efficiency from weight losses, corrosion currents and from impedance measurements are in fair agreement. The inhibition film does not lose efficiency even at anodic polarization, although the AES measurements indicate a change in the organic molecule structure. The hypothesis proposed is that a possible reconstruction of the organic molecule takes place, with release of CS₂.     

Ni-Sn-P合金镀层在人工海水中的腐蚀行为及腐蚀机理

利用扫描电子显微镜(SEM)和能谱(EDS)测试了电镀Ni-Sn-P合金镀层在人工海水中腐蚀前后表面形貌和合金成分的变化,结合X射线光电子能谱(XPS)对腐蚀后合金表面的组成进行了分析,并在此基础上探讨了Ni-Sn-P合金镀层在人工海水中的腐蚀机理。研究结果表明:电镀Ni-Sn-P合金在人工海水中耐蚀性优于Ni-P合金,由于人工海水中的氯离子的穿透效应而出现的局部腐蚀孔数较Ni-P合金大幅减少,腐蚀后Ni-Sn-P合金表面形成由SnO₂、SnCl₄、Ni₃(PO₄)₂、NiO和Ni(OH)₂组成的膜层,对合金耐蚀性的提高起到重要作用。     

Inhibition by <Emphasis Type="Italic">Jasminum nudiflorum</Emphasis> Lindl. leaves extract of the corrosion of cold rolled steel in hydrochloric acid solution

The inhibition effect of Jasminum nudiflorum Lindl. leaves extract (JNLLE) on the corrosion of cold rolled steel (CRS) in 1.0 M hydrochloric acid (HCl) was investigated by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods. The results show that JNLLE acts as a very good inhibitor, and the inhibition efficiency increases with the concentration of JNLLE. The adsorption of JNLLE obeys Langmuir adsorption isotherm. Values of inhibition efficiency obtained from weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) are in good agreement. Polarization curves show that JNLLE behaves as a mixed-type inhibitor in hydrochloric acid. EIS shows that charge-transfer resistance increase and the capacitance of double layer decreases with the inhibitor concentration, confirming the adsorption process mechanism. The adsorbed film on CRS surface containing JNLLE inhibitor was also measured by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). A probable inhibitive mechanism is proposed from the viewpoint of adsorption theory.     

Comparative study on inhibitory performance of an ionic liquid on corrosion of 6061 Al-10(vol.%) SiC(P) composite material and base alloy

Inhibitive performance of 1,3 dimethyl imidazolium dimethyl phosphate (DIDP) towards the corrosion of 6061-Al (10 vol.%) SiC_(P) composite (Al-CM) and base alloy in 0.1 M HCl medium was studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques at different temperatures. Optimization of inhibitor concentration was done to get maximum inhibition efficiency. Thermodynamic parameters were calculated by fitting the results into a suitable adsorption isotherm. Scanning electron microscope (SEM), energy-dispersive X-ray (EDX), and atomic force microscope (AFM) analyses were performed to understand surface morphology, elemental mapping, and surface roughness before and after the addition of DIDP. UV–visible and X-ray diffraction (XRD) tests were performed to confirm the adsorption of inhibitor on the surfaces of materials. Studies revealed an increased rate of corrosion for Al-CM than for the base alloy. The maximum inhibition efficiency for the base alloy was found to be 80.48% for the addition of 1000 ppm, and for Al-CM, it was found to be 87.38% for the addition of 1400 ppm at 303 K. As the temperature increased, the inhibition efficiency decreased. The inhibitor was adsorbed physically on the surface of the metal by obeying the Freundlich adsorption isotherm. Surface studies confirmed the adsorption of DIDP on the surfaces of both Al-CM and the base alloy.     

The influence of EDTA-2Na on microstructure and corrosion resistance of PEO coating for AA1060 alloy

In this study, plasma electrolytic oxidation (PEO) process was applied to AA1060 aluminum alloy in an alkaline-based electrolyte with different concentrations of EDTA-2Na. The investigation of coatings was concentrated on sparks, phase, structure, morphology, and corrosion resistance. The whole process presented a “soft spark” regime which proved by the reduction of light and acoustic emission with increase of current. The results of SEM and EDS showed that more discharge channels were found under surface and the proportion of silicon in the inner layer increased for the sample treated in solution with 5 g/L EDTA-2Na, which was attributed to D type discharge causing some light emission invisible on sample surface. The polarization test presented a better corrosion resistance with the increase of EDTA-2Na. However, EIS measurement showed a bigger corrosion resistance for outer layer of sample prepared with the addition concentration up to 3 g/L that meant outer layer played a more critical role in terms of corrosion resistance.     

The corrosion inhibition of maraging steel under weld aged condition by 1(2E)-1-(4-aminophenyl)-3-(2-thienyl)prop-2-en-1-one in 1.5?M hydrochloric acid medium

The influence of 1(2E)-1-(4-aminophenyl)-3-(2-thienyl)prop-2-en-1-one (ATPI) on the corrosion behavior of weld aged maraging steel in 1.5 M hydrochloric acid was studied by potentiodynamic polarization method and AC impedance (EIS) technique at different temperatures. The results showed that the inhibition efficiency of ATPI increased with the increase in the concentration of inhibitor and decreased with the increase in temperature. ATPI acts as a mixed type inhibitor without affecting the mechanism of the hydrogen evolution reaction or iron dissolution. The adsorption of ATPI on a weld aged maraging steel surface obeys the Langmuir adsorption isotherm equation. Both activation and thermodynamic parameters were calculated and discussed. ATPI inhibits the corrosion through both physisorption and chemisorption on the alloy surface. The surface morphology of the weld aged maraging steel specimens in the presence and the absence of the inhibitors was studied by the respective SEM images.     

阳离子木薯淀粉接枝共聚物对钢在HCl中的缓蚀性能

以木薯淀粉(CS)、丙烯酰胺(AA)及二甲基二烯丙基氯化铵(DMDAAC)为原料,制备出阳离子木薯淀粉接枝共聚物(CCSGC);采用失重法、开路电位-时间曲线、动电位极化曲线、电化学阻抗谱(EIS)和SEM考察了CCSGC对冷轧钢在HCl介质中的缓蚀性能。结果表明:CCSGC在1.0 mol/L HCl溶液中对冷轧钢具有优良的缓蚀作用,20~50℃下,当CCSGC添加量为50 mg/L时,冷轧钢的最大缓蚀率均能超过92%,缓蚀性能明显高于CS、AA、DMDAAC或CS/AA/DMDAAC混合物。CCSGC在钢表面的吸附符合Langmuir吸附等温式,且为混乱度增加、放热的混合吸附过程。CCSGC为通过"几何覆盖效应"同时抑制阴极和阳极的混合抑制型缓蚀剂;EIS结果表明:EIS呈存在弥散效应的容抗弧,电荷转移电阻随CCSGC质量浓度的增加而增大,但双电层电容值却减小。SEM结果表明:CCSGC能有效地抑制钢在HCl中的腐蚀。