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ELECTROChEMICAL NOISE ANALYSIS Of ThE INfLUENCE Of ThE Zn^(2+)IONS CONCENTRATION ON ZINC ELECTROPLATING

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Acta Metallurgica Sinica(English Letters) 2005年第2期18卷 137-144页

作者： Z.Zhang C.S.Wu Q.Y.Cai f.h.cao J.Q.Zhang DepartmentofChemistry ZhejiangUniversityHangzhou310027China DepartmentofChemistry ZhejiangUniversityHangzhou310027China／／StateKeyLaboratoryforCorrosionandProtectionInstituteofMetalResearchTheChineseAcademyofSciencesShenyang110016China

The influence of the concentration of Zn2+ ions on zinc electroplating process was investigated by means of electrochemical noise (EN) and cyclic voltammetry methods in conjunction with the scanning electron microscopy (SEM) technique. It was found that the EN generated during the electroplating of dentritic or large polymeric zinc deposit has large potential oscillation amplitude and positive potential drift while the compact zinc deposit possesses small noise amplitude and little potential drift. With the change of rate determining step from diffusion-control through mixed-control to activation-control, the maximum relative energy obtained from wavelet analysis defined from the region with larger scales to those with smaller scales, and the EDP (relative energy distribution plot) can be us, as 'fingerprints' of EN to characterize the electroplating process and the deposit structure. The results also showed that electrochemical noise technique can give more information about the electrodeposit structure than other normal electrochemical measurements, such as linear potential sweep method and cyclic voltammetry technique.

关键词： zinc electroplating zinc ions concentration electrochemical noise electrodeposit structure

ELECTROChEMICAL NOISE fEATURES Of PURE ALUMINUM DURING PITTING CORROSION IN NEUTRAL NaCl SOLUTION

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Acta Metallurgica Sinica(English Letters) 2003年第1期16卷 20-30页

作者： f.h.cao Z.Zhang Y.L.Cheng J.f.Li J.Q.Zhang J.M.Wang C.N.cao Department of Chemistry Zhejiang UniversityHangzhou 310027China State Key Laboratory for Corrosion and Protection of Metals Institute of Metal ResearchThe Chinese Academy of SciencesShenyang 110016China

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 corrosion rate deterministic step does not involve Cl-.

关键词： pure aluminum pitting corrosion electrochemical noise electrochemical impedance spectroscopy potentiodynamic scanning

INfLUENCE Of SO_4^(2-) AND Cl-ON ThE CORROSION BEhAVIOR Of COPPER TUBE IN AIR-CONDITIONING SYSTEM

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Acta Metallurgica Sinica(English Letters) 2004年第1期17卷 92-96页

作者： C.S.Wu Z.Zhang f.h.cao J.Q.Zhang J.M.Wang C.N.cao Department of Chemistry Yuquan CampusZhejiang University Hangzhou 310027ChinaDepartment of Chemistry Yuquan CampusZhejiang University Hangzhou 310027ChinaDepartment of Chemistry Yuquan CampusZhejiang University Hangzhou 310027ChinaDepartment of Chemistry Yuquan CampusZhejiang University Hangzhou 310027China State Key Laboratory for Corrosion and Protection of Metals Shenyang 110016 ChinaDepartment of ChemistryYuquan Campus Zhejiang University Hangzhou 310027ChinaDepartment of ChemistryYuquan Campus Zhejiang University Hangzhou 310027China State Key Laboratory for Corrosion and Protection of MetalsShenyang 110016 China

The influence of chloride or sulphur dioxide on the corrosion behavior of copper tube in the air-conditioning system was studied using scanning electron microscope (SEM), energy dispersion spectrometer (EDS) and cyclic polarization techniques. The results showed that the corrosion of copper tube are mainly caused by the SO42- and Cl- ions in the circulating water, and the former is mainly responsible for the general corrosion of the copper tube whilst the latter for the pitting corrosion. The different influences of SG42- and Cl- ions on the corrosion type of copper tube may be attributed to that the radius of SO42- ion is much larger than that of Cl- ion. Meanwhile the results also indicated that SO42- inhibits the pitting corrosion caused by Cl- and Cl- inhibits the general corrosion initiated by SO42- due to their competitive adsorption on the copper matrix.

关键词： copper corrosion behavior influence SO42- ion Cl- ion

STUDY Of ThE X70 PIPELINE STEEL CORRODING IN 3.0wt% NaCl SOLUTION USING ELECTROChEMICAL IMPEDANCE SPECTROSCOPY TEChNIQUE

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Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 907-911页

作者： L.J.Zhang Z.Zhang f.h.cao J.Q.Zhang J.M.Wang C.N.cao DepartmentofChemistry ZhejiangUniversityHangzhou310027China DepartmentofChemistry ZhejiangUniversityHangzhou310027China／／ StateKeyLaboratoryforCorrosionandProtectionofMetalsInstituteofMetalResearchTheChineseAcademyofSciencesSlaenyang110016China

The corrosion process of the X70 pipeline steel in 3.0wt% NaCl solution were studied using polarization method, and the chronological characteristics during the entire polarization plot were investigated in detail using EIS technique. In the active region of X70 steel, such as 20mV potential bias applied on open circuit potential (OCP), the impedance spectra was comprised of three parts: a high-frequency capacitive loop, a middle-frequency capacitive loop and a low-frequency inductive component. When positive polarization potential increased, the capacitive loops at high and middle frequency range merged, and the inductive component at low frequency shrunk. At high positive polarization potential bias (500-800mV vs. OCP), the high-frequency capacitive loop and the low-frequency inductive loop exhibited as disheveled points due to the synergism of the inhomogeneity of the corroding material and the localized corrosion. The results were fitted utilizing the equivalent circuits to simulate the impedance spectra and to interpret the electrochemical features shown during the experiments.

关键词： X70 pipeline steel corrosion polarization EIS

STUDY ThE INfLUENCE Of h_(3)BO_(3)ON ThE ZINC ELECTROPLATING USING ELECTROChEMICAL NOISE TEChNIQUE

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Acta Metallurgica Sinica(English Letters) 2004年第5期17卷 661-666页

作者： Z.Zhang C.S.Wu Q.Y.Cai Y.L.Cheng f.h.cao J.Q.Zhang C.N.cao DepartmentofChemistry ZhejiangUniversityHangzhou310027China StateKeyLaboratoryforCorrosionandProtection InstituteofMetalResearchTheChineseAcademyofSciencesShenyang110016China

The influence of h3BO3 on the zinc electroplating was studied using electrochemical noise technique, cyclic voltammetry and steady-state polarization method. The results showed that, under the experimental conditions, the deposition of zinc followed the mechanism of two-dimensional nucleation and subsequent grain growth. The addition of h3BO3 into the electroplating solution prominently changes the nucleation and growth kinetics of zinc deposits, which is directly related to the features of electrocrystallization noise and the corresponding structure of the electrodeposits. The results also shown that the electrochemical noise (EN) technique can give more information about the electrodeposits structure and electroplating mechanism than other normal electrochemical measurements can give, such as steady-state polarization method and cyclic voltammetry technique.

关键词： zinc electroplating electrochemical noise electrocrystallization

Removal of Cd^(2+) from water by friedel's salt (fS:3cao·A1_2O_3 ·CaCl_2 ·10h_2O): Sorption characteristics and mechanisms

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Journal of Environmental Sciences 2013年第9期25卷 1719-1725页

作者： Juanjuan Zhang he Zhao hongbin cao heping Li Zhibao Li Key Laboratory of Green Process and Engineering Institute of Process Engineering Chinese Academy of Sciences College of Chemical and Biologic Engineering Changsha University of Science and Technology National Engineering Laboratory for hydrometallurgical Cleaner Production Technology

The development of low-cost and efficient new mineral adsorbents has been a hot topic in recent years. In this study, friedel＇s salt （fS：3cao·A12O3 ·CaCl2 ·10h2O）, a hexagonal layered inorganic absorbent, was synthesized to remove Cd2＋ from water. The adsorption process was simulated by Langmuir and freundlich models. The adsorption mechanism was further analyzed with TEM, XRD, fT-IR analysis and monitoring of metal cations released and solution ph variation. The results indicated the adsorbent fS had an outstanding ability for Cd（Ⅱ） adsorption. The maximum adsorption capacity of the fS for Cd（Ⅱ） removal can reach up to 671.14 mg/g. The nearly equal numbers of Cd2＋ adsorbed and Ca2＋ released demonstrated that ion-exchange （both surface and inner） of the fS for Cd（Ⅱ） played an important role during the adsorption process. furthermore, the surface of the fS after adsorption was microscopically disintegrated while the inner lamellar structure was almost unchanged. The behavior of Cd（Ⅱ） adsorption by fS was significantly affected by surface reactions. The mechanisms of Cd2＋ adsorption by the fS mainly included surface complexation and surface precipitation. In the present study, the adsorption process was fitted better by the Langmuir isotherm model （R2 = 0.9999） than the freundlich isotherm model （R2 = 0.8122）. finally, due to the high capacity for ion-exchange on the fS surface, fS is a promising layered inorganic adsorbent for the removal of Cd（Ⅱ） from water.

关键词： friedel’s salt cadmium adsorption isotherm mechanism

Diameter-dependent in vitro performance of biodegradable pure zinc wires for suture application

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Journal of Materials Science & Technology 2019年第8期35卷 1662-1670页

作者： h. Guo R.h. cao Y.f. Zheng J. Bai f. Xue C.L. Chu State Key Laboratory for Turbulence and Complex System and Department of Materials Science and Engineering College of Engineering Peking University Beijing 100871 China School of Materials Science and Engineering Southeast University Nanjing 211189 China Key Laboratory for Advanced Metallic Materials Southeast University Nanjing 211189 China

In this study, biodegradable pure zinc wires with 3.0 mm and 0.3 mm in diameter were prepared via hot-extrusion and subsequent cold-drawing process respectively. The microstructure, mechanical performance, corrosion behavior, in vitro cytocompatibility and antibacterial effect were comparatively *** cold-drawing, the mechanical property, especially the elongation of the ф0.3 mm pure Zn wire was improved significantly compared with the ф3.0 mm pure Zn wire. The in vitro corrosion study including immersion and electrochemical test showed acceptable corrosion resistance of these two materials in hank's solution. The in vitro human Umbilical Vein Endothelial Cells(hUVECs) viability assay showed obviously different results, in which the ф0.3 mm pure Zn wire demonstrated favorable cytocompatibility, while the ф3.0 mm wire exhibited severe cytotoxic effect with 100% extract concentration. Both of them exhibited partly antibacterial effect on S. aureus. These results demonstrated the feasibility of the prepared 0.3 mm pure Zn wire as the potential suture material with good absorbability.

关键词： Pure zinc Wire Biodegradable metal Suture

Review on hydrogen Embrittlement of Press-hardened Steels for Automotive Applications

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Acta Metallurgica Sinica(English Letters) 2023年第7期36卷 1123-1143页

作者： Z.Wang Q.Lu Z.h.cao h.Chen M.X.huang J.f.Wang General Motors China Science Lab Shanghai201206China Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong Kong999077China Key Laboratory for Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing100084China

Press-hardened steel(PhS)with an ultimate tensile strength(UTS)of 1500 MPa has been widely used in automotive body-in-white in the last two decades,due to its ultra-high strength and excellent formability that is achieved by hot stamping ***,the application of PhS with UTS exceeding 1500 MPa in automotive industry could be deferred due to the increased risk of hydrogen *** reduce this kind of risk,recent research efforts have been focused on various ways to optimize the microstructure of *** present review intends to summarize these efforts,to highlight present solutions to address hydrogen embrittlement,and to shed light on directions for future *** influence of microstructure on the hydrogen embrittlement of PhS has been discussed in terms of both the steel substrate and the surface *** substrate part covers the influence of martensite,carbides,inclusions,and retained austenite,while the surface part covers decarburization and oxidation,pre-coating,and trimming.

关键词： hot stamping Press-hardened steels Coating-free hydrogen embrittlement fracture Al-Si coating

Influence of Al^(3+) on hydrothermally Synthesized Xonotlite Whiskers in cao-SiO_2-h_2O System

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稀有金属材料与工程 2011年第S3期40卷 99-101页

作者： Li Jing, Liu fei, cao Jianxin Guizhou University, Guiyang 550003, China Guizhou Univ Sch Chem & Chem Engn Guiyang 550003 Peoples R China

Influences of Al3+ concentration on hydrothermally synthesized xonotlite whiskers were researched in this paper. The crystal phase composition and morphology of the products were analyzed and characterized using XRD and SEM techniques. The results indicate that Al3+ concentration have great impact on the crystal phase composition and morphology of the xonotlite whiskers in cao-SiO2-h2O system under the condition of initial cao/SiO2 mol ratio of 1.0, reactant concentration of 0.05 mol·L-1 , at 225 ℃ for 15 h. The main crystal phase of hydrothermally synthesized products had a phase transition from xonotlite to tobermorite, and the morphology changed from fibrous to tabular with increasing the concentration of Al3+ ion. At last, in order to prepare the pure xonotlite whiskers via hydrothermal synthesis in cao-SiO2-h2O system, the Al2O3 contents in raw materials should be less than 1%.

关键词： xonotlite whisker Al3+ ion hydrothermal synthesis