材料期刊网

Electrochemical Behaviour of Cu underneath Thin Electrolyte Film in Atmosphere

Xueyuan ZHANG and Yuanlong DU(State Key Lab. for Corrosion and Protection , Institute of Corrosion and Protection of Metals , Chinese Academy of Sciences , Shenyang 110015 , China)

材料科学技术（英文）

An electrochemical cell was devised to investigate corrosion electrochemical behavior of metal underneath thin electrolyte film in atmosphere. The Piontelli's type of Luggin-Haber capillary was inserted from the backward of working electrode. The results show that, cathodic process on Cu is mainly affected by the thickness of the electrolyte film of 0.5 mol/L HCl +1 mol/LNa2SO4 aqueous solution and its anodic dissolution changed from Tafel region to limiting diffusion current.Moreover, the corrosion potential of Cu in due media will increase with decrease of the thickness of the film.

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Relationship between the Brittlement Susceptibility and H Permeation Current for UNS G11180 Steel in 5% NaCl Solution with H_2S

Xueyuan ZHANG and Yuanlong DU(State Key Lab. for Corrosion and Protection , Institute of Corrosion and Protection of Metals , Chinese Academy of Sciences , Shenyang 110015 , China)

材料科学技术（英文）

Sulfide stress corrosion cracking (SSCC) behaviour of UNS G11180 steel in 5% NaCl solution with H2S was studied by slow strain rate tensile test (SSRT), SEM and electrochemical hydro gen permeation technique. The results reveal different cracking mechanism and H permeation current (IH) through UNS G11180 steel plate in different concentration of H2S solution. The susceptibility to SSCC of UNS G11180 Steel in 5% NaCl solution with H2S was evaluated by the permeation current(IH, μA), which depends on the concentration (c×10-6) of H2S by the equation:IH = 8.525 ×c0.7249. lt is proved that the electrochemical H permeation method is a practical way to assess the susceptibility to SSCC.

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Corrosion protection of stainless steel by separate polypyrrole electrode in acid solutions

Materials and Corrosion-Werkstoffe Und Korrosion

Galvanic anodic protection (GAP) of stainless steels by doped polypyrrole (PPy) was investigated using chemically synthesized PPy. Separate PPy powder-pressed electrodes with different surface areas were prepared. Electrochemical properties of PPy electrodes were studied by open circuit potentials (OCPs) and potentiostatic polarization. PPy powder-pressed electrodes were coupled with 410-stainless steel electrodes in different concentrations of sulfuric acid solutions, 5 M phosphoric acid solution, and industrial phosphoric acid solution (5 M phosphoric acid + 0.05% chloride ion). Remarkable shift of OCP to the positive direction and sharp decrease of corrosion rate were observed during the coupling experiments, which implies that 410-stainless steel was transferred to passive state. Results also showed that PPy electrode with sufficient surface area can provide corrosion protection to 410-stainless steel electrode in highly corrosive acid solution. Based on the experiment results, GAP provided by PPy and PANi (synthesized under similar conditions) was compared.

关键词: galvanic anodic protection;organic metal polyaniline;coated;mild-steel;conducting polymers;doped polyaniline;ferrous-metals;carbon-steel;coatings;iron;passivation

CORROSION PROTECTION OF Al CATHODES IN ZINC ELECTROLYSIS

F. Lu and WJ. van Ooij( Beijing Institute of Aeronautical Materials , P.O. Box 81-5 , Beijing 100095 , China)( Department of Materials Science and Engineering , University of Cincinnati , Cincinnati , OH 45221-0012 , U.S.A.)

金属学报(英文版)

Zn-Al couple's galvanic coeeosion was a serious problem in acdic ainc sulfate solution .In this paper, a new pretreatment or a coating for Al was developed and tested to protect the Al effectively form corrosion when connected to pure Zinc at electroplating potential,and exposed to an acdic sulfate solution.Corrosion measurement techniques(Galvanic corrosion and DC)were used to investigate galvanic corrosion between Al cathode and Zn anode.It was found out that Al alloy purity and electroplating potential have a large effect on galvanic corrsion between Zn-Al couples.EIS,salt spray test and immersion test were performed to evaluate the method for Al cathodes in zinc electrolyte,BTSE silane pretreatment and polyurethane coating displayed better corrosion protection.Calculation showed the Al dissolution rate is small enough for Al cathode to be used in zinc plants.BTSE treatment or BTSE plus polyurethane coating has the best corrosion performance,and willprotect the Al cathode effectively in zinc electrolysis

关键词: Al-Zn couple , null

Adsorption behaviour of Schiff base and corrosion protection of resulting films to copper substrate

Corrosion Science

Self-assembled (SA) films of Schiff base were prepared on the copper surface. The corrosion protection abilities of SA films in chloride solution were evaluated using electrochemical impedance spectroscopy and polarization curves. A subsequent adsorption of 1-dodecanethiol on the original SA films of Schiff base improved significantly the protection ability to the copper substrate. The behavior of Schiff base adsorption on copper surface and subsequent adsorption of 1-dodecanethiol was probed by X-ray photoelectron spectroscopy. It was found that copper exists mainly in Cu(I) state in the SA films of Schiff base, and the thiol molecules subsequently adsorbed was bonded directly on copper surface rather than physisorbed on the previous SA films. (C) 2002 Elsevier Science Ltd. All rights reserved.

关键词: self-assembly;Schiff base;copper corrosion;alkanethiol;self-assembled monolayers;hydrochloric-acid solution;gold;alkanethiols;impedance;surfaces;electrodissolution;dissolution;mechanisms;kinetics

Preparation and EIS studies on polyimide/polyaniline blend film for corrosion protection

Polymers for Advanced Technologies

A corrosion protection coating from polyimide/polyaniline (PI/PAn) blend was prepared by solution blending and the anti-corrosion property of this coating was studied with electrochemical impedance spectroscopy technique. The results show that PAn can react with PI to form chemical bonds between these two polymers and these bonds keep these two polymers as a miscible system. The corrosion protection property of this coating increases with a growth in the PAn component and an excellent anti-corrosion effect emerges when the PAn content reaches 10-15%. The reason why PAn can improve the anti-corrosion property is that PI/PAn blend can form a dense and non-porous polymer film that would prevent some corrupting components from access to the underlying steel surface. And also, PAn may serve as a corrosion inhibiting agent to scavenge any protons and foster a local basic surface environment. Copyright (C) 2001 John Wiley Sons, Ltd.

关键词: polyaniline;polyimide;corrosion;EIS

A study on cathodic protection against crevice corrosion in dilute NaCl solutions

Corrosion Science

Potential and current distributions in a cathodically protected crevice between a simulated coating and segmented mild steel electrodes were measured in dilute NaCl solutions. The distributions became more uniform with time due to an increase in solution conductivity and depletion of dissolved oxygen in the crevice. Generally, a negative shift of control potential and an increase in initial solution conductivity and crevice thickness resulted in a higher polarization level on the steel. However, if the control potential is too negative, the polarization level may be lower than that under a suitable control potential because of hydrogen evolution. On the basis of these results, a mechanism of cathodic protection against crevice corrosion in high-resistivity environments was proposed. (C) 2002 Elsevier Science Ltd. All rights reserved.

关键词: cathodic protection;crevice corrosion;potential distribution;current;distribution;mild steel;dilute NaCl solution;coatings

Corrosion Behavior and Protection Efficiency of 2024Al and SiCp2024Al Metal Matrix Composite

Chunlin HE , Changsheng LIU , Fengqin LI , Qingkui CAI , Zhiming SHI , Liqing CHEN , Jing BI

材料科学技术（英文）

The corrosion resistance of 2024 Al and SiC particle reinforced 2024 Al metal matrix composite (SiCp/2024Al MMC) in 3.5% NaCl solution was investigated with electrochemical method and immersion test, and the corrosion protection of sulfuric acid anodized coatings on both materials was evaluated by electrochemical impedance spectroscopy. The results showed that the SiCp/2024Al MMC is more susceptible to corrosion than its matrix alloy in 3.5% NaCl. For 2024Al, the anodized coating provides excellent corrosion resistance to 3.5% NaCl.The anodized coating on the SiCp/2024Al provides satisfactory corrosion protection, but it is not as effective as that for 2024Al because the structure of the anodized layer is affected by the SiC particulates.

关键词: 2024 Al , null , null , null

Corrosion protection of aluminium alloy 2024-T3 in 0.05 M NaCl by cerium cinnamate

Corrosion Science

The corrosion protection of AA 2024-T3 in 0.05 M NaCl by cerium cinnamate has been studied. Polarization measurements demonstrate that cerium cinnamate is markedly effective for suppressing anodic process of the alloy corrosion during the initial 72 h of immersion. The protection mechanism during the immersion period appears to involve two stages: the deposition of cerium cinnamate, and then hydrolysis of cerium ions forming a cerium oxide/hydroxide, prevailing over the foregoing deposition. This study also elucidates the inhibition effect of cerium cinnamate on the early corrosion attack occurred from the second phase particles by X-ray photoelectron spectroscopy and electron-probe microanalysis. (C) 2011 Elsevier Ltd. All rights reserved.

关键词: Alloy;Rare earth elements;EIS;XPS;Neutral inhibition;chromate conversion coatings;hydroxy carboxylic-acids;pitting;corrosion;galvanized steel;amino-acids;inhibition;xps;al;polymer;salts

The effect of epoxy coating containing emeraldine base and hydrofluoric acid doped polyaniline on the corrosion protection of AZ91D magnesium alloy

Corrosion Science

Corrosion protection of epoxy coatings containing emeraldine base polyaniline (PANI) or hydrofluoric acid doped PANI on AZ91D magnesium alloy were studied by EIS and Pull-Off Adhesion Test. The results indicated that the addition of emeraldine base PANI or hydrofluoric acid doped PANI could improve the corrosion resistance of epoxy coating. The epoxy coating containing hydrofluoric acid doped PANI had the best performance of the corrosion protection among three systems under investigation. The corrosion product film was analyzed by XPS indicating that PANI changed the chemical structure of the corrosion film. The protective mechanism imparted by PANI was discussed. (C) 2011 Elsevier Ltd. All rights reserved.

关键词: Organic coatings;Magnesium;EIS;XPS;x-ray photoelectron;mild-steel;electrochemical-behavior;stainless-steel;passivation mechanism;conversion coatings;buffer;solution;part 2;spectroscopy;inhibition