Co-reporter:Hui-ping Wang 王慧萍;Shao-chun Ding 丁少春;Juan Zhu 朱娟
Journal of Central South University 2015 Volume 22( Issue 3) pp:806-814
Publication Date(Web):2015 March
DOI:10.1007/s11771-015-2586-7
The corrosion behavior of 907 steel under thin electrolyte layer (TEL) has been investigated by means of cathodic polarization curve measurement, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The results show that the cathodic diffusion current density presents the variation trend of initial increase and subsequent decrease with the decrease of TEL thickness, and the maximum deposits at 58 μm. The cotangent-hyperbolic impedance (O) is rationally first introduced to study the diffusion process of the reactants through the corrosion products layer with many permeable holes. The initial corrosion rate of 907 steel under different TEL thickness increases with the decrease of TEL thickness except that of 104 μm, whereas the corrosion rate after long time corrosion can be ranked as 104 μm>402 μm>198 μm>301 μm >bulk solution.
Co-reporter:Yang Yang, Yumeng Yang, Xiaoqing Du, Yu Chen, Zhao Zhang, Jianqing Zhang
Applied Surface Science 2014 Volume 305() pp:330-336
Publication Date(Web):30 June 2014
DOI:10.1016/j.apsusc.2014.03.078
Highlights
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The oxidation of Ce3+ ions is under charge–transfer control.
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The preferential crystal orientation changes to (1 1 1) plane at higher temperatures.
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Dissolving oxygen favors cerium oxide particles and films generation.
Co-reporter:Xianqiu Huang, Yu Chen, Jianqi Zhou, Zhao Zhang, Jianqing Zhang
Journal of Electroanalytical Chemistry 2013 Volume 709() pp:83-92
Publication Date(Web):15 November 2013
DOI:10.1016/j.jelechem.2013.09.012
•Initial reduction process is diffusion-controlled and follows 3D nucleation.•New models are developed to analyze the current transient.•Proton reduction on both tin centre and steel surface at low overpotential.•Proton reduction on tin centre at high overpotential.•Diffusion coefficient of tin species is found to be 1.24E−5 cm2 s−1.Cyclic voltammetry (CV), chronoamperometry (CHR) in conjunction with scanning electron microscopy (SEM) technique have been performed to study the electrodeposition behavior of tin onto double reduction steel substrate from a stannous fluoborate acid bath. Results show that, under the experimental conditions, the initial reduction process of tin is controlled by diffusion and follows the three-dimensional (3D) nucleation and subsequent grain growth mechanism. With the increase of the applied cathodic overpotentials, the nucleation type of tin changes from progressive mechanism to instantaneous mechanism. When the deposition overpotential is high, the electrode surface is fully covered with tin deposits in short times that the current–time transient is composed of the tin nucleation current and the current attributed to proton reduction on the tin growth centers while the current due to proton reduction on the steel surface should be considered as well at low deposition overpotentials. Results also reveal that both the tin nucleation and proton reduction rate constant increase with increasing the cathodic overpotentials, and the proton reduction rate constant on the steel substrate surface is larger than that on the tin growth centers. The diffusion coefficient of tin species is found to be 1.24E−5 cm2 s−1.
Co-reporter:Y. Chen;Y. Y. Jiang;H. Chen;Z. Zhang
Journal of the American Oil Chemists' Society 2013 Volume 90( Issue 9) pp:1387-1395
Publication Date(Web):2013 September
DOI:10.1007/s11746-013-2283-3
A new kind of corrosion inhibitor (LOBI) based on linseed oil has been synthesized. The molecular structure of LOBI was investigated using Fourier transform infrared spectroscopy and nuclear magnetic resonance spectrometer. Its inhibiting behavior on mild steel in 1.0 M HCl was studied by electrochemical potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. Results reveal that LOBI was a good mixed-type inhibitor. The adsorption of LOBI at 40 °C obeys the Langmuir adsorption isotherm. The N(1s) and S(2p) peaks of XPS measurement indicate that LOBI has been adsorbed onto a Q235 steel surface. The adsorption equilibrium constant, adsorption free energy and activation energy were also calculated, which indicated the adsorption of LOBI was chemisorption.
Co-reporter:Y. Chen, Q.P. Wang, C. Cai, Y.N. Yuan, F.H. Cao, Z. Zhang, J.Q. Zhang
Thin Solid Films 2012 Volume 520(Issue 9) pp:3553-3557
Publication Date(Web):29 February 2012
DOI:10.1016/j.tsf.2012.01.007
Nanocrystalline Co45Ni10Fe24 films have been fabricated using cyclic voltammetry technique from the solutions containing sulfate, then characterized by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer. Meanwhile, Electrochemical Impedance Spectroscopy technique has been employed to probe into the nucleation/growth behavior of Co45Ni10Fe24 films. The results show that, the obtained Co45Ni10Fe24 film possesses low coercivity of 973.3 A/m and high saturation magnetic flux density of 1.59 × 105 A/m. Under the experimental conditions, the nucleation/growth process of Co45Ni10Fe24 films is mainly under activation control. With the increase of the applied cathodic potential bias, the charge transfer resistance for CoNiFe deposition decreases exponentially.Highlights► Nanocrystalline Co45Ni10Fe24 film is obtained using cyclic voltammetry technique. ► Nanocrystalline Co45Ni10Fe24 possesses low coercivity of 973.3 A/m. ► Nanocrystalline Co45Ni10Fe24 possesses high saturation magnetic flux density. ► The nucleation/growth process of CoNiFe films is mainly under activation control. ► The charge transfer resistance for CoNiFe deposition decreases exponentially.
Co-reporter:Yan Liu, Zhongling Wei, Fuwei Yang, Zhao Zhang
Journal of Alloys and Compounds 2011 Volume 509(Issue 22) pp:6440-6446
Publication Date(Web):2 June 2011
DOI:10.1016/j.jallcom.2011.03.083
A kind of environmental friendly anodizing routine for AZ91D magnesium alloy, based on an alkaline borate–sodium benzoate electrolyte (NaBz) was studied. The effect of NaBz on the properties of the anodized film was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), respectively. The results showed that the anodizing process, surface morphology, thickness, phase structure and corrosion resistance of the anodized film were strongly dependent on the concentration of NaBz. In the presence of adequate NaBz, a thick, compact and smoothing anodized film with excellent corrosion resistance was produced. Moreover, the forming mechanism of the anodized film in the presence of NaBz additive was also approached, which was a suppression of arc discharge process by the adsorption of Bz− on the surface of magnesium alloy substrate.Highlights► Environmental friendly PEO technology for AZ91 magnesium alloy is developed. ► NaBz is used as new additive and it is low-cost and environmental friendly. ► The effect of NaBz additive on the properties of the anodized film was studied. ► Anodized film with excellent corrosion resistance is obtained. ► The forming mechanism of anodized film in the presence of NaBz is approached.
Co-reporter:C. Cai, X.B. Zhu, G.Q. Zheng, Y.N. Yuan, X.Q. Huang, F.H. Cao, J.F. Yang, Z. Zhang
Surface and Coatings Technology 2011 205(11) pp: 3448-3454
Publication Date(Web):
DOI:10.1016/j.surfcoat.2010.12.002
Co-reporter:M.J. Zhao, C. Cai, L. Wang, Z. Zhang, J.Q. Zhang
Surface and Coatings Technology 2010 205(7) pp: 2160-2166
Publication Date(Web):
DOI:10.1016/j.surfcoat.2010.08.129
Co-reporter:Y.Y. Shi, Z. Zhang, F.H. Cao, J.Q. Zhang
Electrochimica Acta 2008 Volume 53(Issue 6) pp:2688-2698
Publication Date(Web):15 February 2008
DOI:10.1016/j.electacta.2007.07.072
In this work, two new indices, SE and SG are proposed to evaluate pitting corrosion by dimensional analysis of three parameters of PSD, the slope of high frequency linear region (k), the critical frequency (fc) and the low-frequency plateau level (W). And then they are employed to analyze the potential electrochemical noise obtained during the corrosion processes of stainless steel 1Cr18Ni9Ti and pure Al, two materials most susceptible to pitting corrosion in NaCl solutions. Meanwhile another two mathematical methods, statistics and wavelet transform techniques, are also carried on the same potential oscillation data to estimate the function (meaning) of these two indices (SE and SG) in monitoring corrosion processes. The results suggest that, the index SE is directly proportional to the rapider potential oscillating and higher fluctuation amplitude and can be used to depict the distribution behavior of electrochemical noise, while the index SG can be used to depict the slower corrosion processes.
Co-reporter:L.J. Zhang, J.J. Fan, Z. Zhang, F.H. Cao, J.Q. Zhang, C.N. Cao
Electrochimica Acta 2007 Volume 52(Issue 17) pp:5325-5333
Publication Date(Web):5 May 2007
DOI:10.1016/j.electacta.2006.12.083
The formation of anodic film of AZ91D magnesium alloy has been investigated by means of electrochemical impedance spectroscopy (EIS), cyclic voltammetry, anodic polarization curve, current–time transients and SEM technique. The results show that, under our experimental conditions, the formation of AZ91D anodic film follows the mechanism of 3D nucleation with diffusion controlled growth. With the increase of applied anodizing potential, the nucleation type of anodic film changes from progressive to instantaneous. The results also show that the initially formed anodized film is threadlike and porous, and high potential is essential for the formation of good anodic film with excellent properties.
Co-reporter:C.S. Wu, Z. Zhang, F.H. Cao, L.J. Zhang, J.Q. Zhang, C.N. Cao
Applied Surface Science 2007 Volume 253(Issue 8) pp:3893-3898
Publication Date(Web):15 February 2007
DOI:10.1016/j.apsusc.2006.08.020
Abstract
A kind of environmentally friendly anodizing route for magnesium alloys, based on a new kind of organic additive (AA) contained traditional alkaline borate solution and 50 Hz civil ac current, has been studied. It is found that the formation of the anodic films is always coupled with the additive depended sparking and oxygen evolution, and the optimized ivory-white smooth anodic film possesses high corrosion resistance and excellent binding strength to AZ31 substrate. Meanwhile, The results also show that the structure, the corrosion resistance and the morphology of the anodic films are mainly dependent on the anodizing voltage, time and additives.
Co-reporter:Yanyan Shi, Zhao Zhang, Jingxin Su, Fahe Cao, Jianqing Zhang
Electrochimica Acta 2006 Volume 51(Issue 23) pp:4977-4986
Publication Date(Web):15 June 2006
DOI:10.1016/j.electacta.2006.01.050
Potential noise records have been collected for 2024-T3 aluminum alloy, which was exposed to simulated acid rain with different pH value for 15 wet–dry cycles. Meanwhile, Potentiodynamic polarization and SEM techniques were also used as assistant measurements. Three mathematic methods including average, standard deviation and wavelet transformation have been employed to analyze the records. The results showed that each single wet–dry cycle can be divided into three regions with respect to the change of the cathodic reaction rate, and with the increase of pH value the main cathodic reaction changes from the reduction of protons to that of oxygen molecules. The analysis of the EDP versus time evolution clearly indicates that the whole corrosion process can be divided into three segments for the case of pH 3.5 and only one for the cases of pH 4.5 and 6.0, which have been theoretically interpreted according to the corrosion theory and experimentally proved by SEM. The results also showed that the corrosion in the case of pH 3.5 was much more rigorous than that in the cases of pH 4.5 and 6.0. It may due to synergistic effects of that, the characteristic of hydrogen ions which is much more active than that of oxygen molecules, the high diffusion/migration rate of hydrogen ions in solution or through surface films and the lower stability of surface passive film at low pH value system.
Co-reporter:C.B Ma, F.H Cao, Z. Zhang, J.Q Zhang
Applied Surface Science 2006 Volume 253(Issue 4) pp:2251-2256
Publication Date(Web):15 December 2006
DOI:10.1016/j.apsusc.2006.04.037
Abstract
Decorative and protective Ni–P amorphous coatings were electroplated onto NdFeB permanent magnet from an ortho-phosphorous acid contained bath. The influences of the main electroplating technological parameters including current density, bath pH, bath temperature and H3PO3 on the structure and chemical composition of Ni–P coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques in conjunction with X-ray diffraction (XRD), scanning transmission electron microscopy (SEM) and X-ray energy-dispersive spectrometry (EDX). The optimized amorphous Ni–P coated NdFeB can stand for ca. 180 h against neutral 3.0 wt.% NaCl salt spray without any pitting corrosion. Meanwhile, the results also showed that large phosphorous content is the precondition for Ni–P coatings to possess the amorphous structure, but too much high phosphorous content can damage the amorphous structure due to the separation of superfluous P from Ni2P/Ni3P and the resultant formation of multi-phase coatings (such as Ni2P–P).
Co-reporter:Z.N. Yang, Z. Zhang, J.Q. Zhang
Surface and Coatings Technology 2006 Volume 200(16–17) pp:4810-4815
Publication Date(Web):27 April 2006
DOI:10.1016/j.surfcoat.2005.04.026
Cyclic voltammetry and chronoamperometry were performed in conjunction with SEM technique to study the electroplating process of Zn–Fe alloys. The technological parameters for Zn–Fe electroplating have been optimized and the smooth Zn–Fe coatings with high corrosion resistances were obtained. The results also show that, under our experimental conditions, the deposition of Zn–Fe behaved anomalously and followed the mechanism of three-dimensional (3D) nucleation. With the increase of deposition potential, the grain growth changed from progressive to instantaneous. Meanwhile, a new viewpoint was proposed to explain the anomalous co-deposition behavior of Zn–Fe coatings.
Co-reporter:Z. Zhang, W.H. Leng, Q.Y. Cai, F.H. Cao, J.Q. Zhang
Journal of Electroanalytical Chemistry 2005 Volume 578(Issue 2) pp:357-367
Publication Date(Web):1 May 2005
DOI:10.1016/j.jelechem.2005.01.029
The zinc electroplating process was investigated by means of electrochemical noise (EN), cyclic voltammetry and steady-state polarization methods in conjunction with the scanning electron microscopy (SEM) technique. It was found that the EN generated during the electroplating of dentritic or large conglomerate zinc deposit has large potential oscillation amplitude and positive potential drift while the compact zinc deposit possesses small noise amplitude and little potential drift. Meanwhile, the electrocrystallization EN time-domain records were analyzed using wavelet transform technique, the results shown that, with the change of the rate determining step of zinc electroplating process from diffusion-control through mixed-control to activation-control, the maximum relative energy of the EDP (relative energy distribution plot) obtained from wavelet analysis shifted from the region with larger scales to those with smaller scales, and the corresponding deposit structure changed from dentritic to compact, i.e., the EDP can be used as “fingerprints” of EN to characterize the electroplating process and the deposit structure. The results also shown that electrochemical noise technique can give more information about the deposit structure than other normal electrochemical measurements, such as linear potential sweep method and cyclic voltammetry technique.
Co-reporter:Chao Cai, Zhao Zhang, Fahe Cao, Zuoning Gao, Jianqing Zhang, Chunan Cao
Journal of Electroanalytical Chemistry 2005 Volume 578(Issue 1) pp:143-150
Publication Date(Web):15 April 2005
DOI:10.1016/j.jelechem.2004.12.032
The potential electrochemical noise (EN) measurements in conjunction with the scanning electron microscopy (SEM) technique have been used to study the corrosion behavior of pure aluminum in neutral 3.0 wt% sodium chloride solution. EN information on the evolution of pitting corrosion over a period of five days has been obtained and analyzed with a wavelet transform technique. The results show that the EN signal was composed of a distinct type of events characterized by small scaling values, i.e., their time constants, and the wavelet transform technique is a useful alternative tool to overcome the limitations of FFT. Meanwhile, it is found that the energy distribution plots (EDP) can be used as “fingerprints” of EN signals, and good correspondence between the characteristics of EDP and the material corrosion type/severity has been obtained. Finally, the relationship between the EN features and the corrosion morphologies has been elucidated according to the “autoacceleration” and “cathodic protection” mechanisms of the corrosion process.
Co-reporter:Y.L. Cheng, Z. Zhang, F.H. Cao, J.F. Li, J.Q. Zhang, J.M. Wang, C.N. Cao
Corrosion Science 2004 Volume 46(Issue 7) pp:1649-1667
Publication Date(Web):July 2004
DOI:10.1016/j.corsci.2003.10.005
The corrosion of aluminum alloy 2024-T3 (AA2024-T3) under thin electrolyte layers was studied in 3.0 wt% sodium chloride solutions by cathodic polarization and electrochemical impedance spectroscopy (EIS) method. The cathodic polarization measurements show that, when the electrolyte layer is thicker than 200 μm, the oxygen reduction current is close to that of the bulk solution. But in the range of 200–100 μm, the oxygen reduction current is inversely proportional to the layer thickness, which shows that the oxygen diffusion through the electrolyte layer is the rate-determining step for the oxygen reduction process. In the range of 100 μm to about 58 μm, the oxygen reduction current is slightly decreased probably due to the formation of aluminum hydroxide or the change of the diffusion pattern from 2-dimensional diffusion to one-dimensional diffusion. The further decrease in electrolyte layer thickness increase the oxygen reduction current to some extent again, because the diffusion of oxygen plays more important role in thin electrolyte layers.The EIS measurements show that the corrosion is controlled by the cathodic oxygen reduction at the initial stage, showing the largest corrosion rate at the electrolyte layer thickness of 105 μm. But at the later stage of corrosion, the anodic process begin to affect the corrosion rates and the corrosion rates show a maximum at 170 μm, which may be the thickness where the corrosion changes from cathodic control to anodic control. The corrosion rate under the very thin electrolyte layer (62 μm in this study) is even smaller than that in bulk solution, this is due to that the anodic process is strongly inhibited.
