J.H.Dong 1)
,
J.Y.Chen 2
,
3) and. C.N.Cao 1) 1) State Key Laboratory for Corrosion and Protection of Metals
,
Institute of Corrosion and Protection of Metals
,
The Chinese Academy of Sciences
,
Shenyang 110015
,
China 2) The International Center for Materials Physics
,
CAS
,
Shenyang 110015
,
China 3) Shenyang Normal College
,
Shenyang 110031
,
China
金属学报(英文版)
The effect of chloride ion on the corrosion inhibition of iron caused by dencylamine(DA), dipentylamine(DDA) and dodecylamine(DPA) has been investigated by measuring the inhibitory coefficients for the anodic and cathodic processes at corrosion potential. It has been shown that the major synergistic inhibition effects between amines and chloride ions occur in the cathodic process, very weak in the anodic process. The anodic inhibition mechanism follows the competing adsorptive model, while the cathodic inhibition mechanism follows the cooperative adsorptive model.
关键词:
synergistic inhibition
,
null
,
null
Corrosion Science
An electrochemical investigation was carried out to study the corrosion of pure magnesium in 1 N NaCl at different pH values involving electrochemical polarisation, scanning tunnel microscopy (STM), measurement of hydrogen gas evolution and measurement of the elements dissolved from the magnesium specimen which were determined by inductively coupled plasma atomic emission spectrophotometry (ICPAES). A partially protective surface film was a principal factor controlling corrosion. Film coverage decreased with increasing applied electrode potential. Application of a suitable external cathodic current density was shown to inhibit magnesium dissolution whilst at the same time the hydrogen evolution rate was relatively small. This showed that cathodic protection could be used to significantly reduce magnesium corrosion. A new definition is proposed for the negative difference effect (NDE). (C) 1997 Elsevier Science Ltd.
关键词:
magnesium;electrochemical corrosion;cathodic protection;STM;kinetics;behavior;mg
Journal of Alloys and Compounds
La1-xSrxCrO3 (x=0.0 similar to 0.5) samples were prepared by the sol-gel method. The crystal structures of La1-xSrxCrO3 at room temperature all are of the othorhombic perovskite GdFeO3-type. XPS analysis indicates that chromium ions are in mixed valence state. The introduction of Sr2+ into the lattice is compensated by the oxidation from Cr3+ to Cr6+ With x increasing, the amount of Cr6+ increases. The presence of the Cr6- is one of the key factors that affect the electric conductivity of La1-xSrxCrO3. (C) 2000 Elsevier Science S.A. All rights reserved.
关键词:
rare earth;perovskite La1-xSrxCrO3;high-temperature conductivity;interconnector;XPS
Electrochimica Acta
Electrically conducting polypyrrole (Ppy) coatings doped with sodium dodecylsulfate (SDS) have been deposited on 1Cr18Ni9Ti stainless steel by anodic polymerization from aqueous solutions of pyrrole and sodium dodecylsulfate. The corrosion behavior of Ppy coated steel was investigated in 0.3 M HCl aqueous solution at room temperature by a combination of electrochemical measurement techniques and scanning electron microscopy. The steel is in active state at the open circuit potential and suffers from pitting corrosion when the polarization potential is higher than 210 mV versus SCE. The Ppy coating can increase the corrosion potential of the steel by more than 600 mV versus SCE, and the pitting corrosion potential by more than 500 mV versus SCE. Fifty-day exposure experiments indicated that the Ppy coating shows high stability, and can inhibit effectively the corrosion of the steel. (C) 2005 Elsevier Ltd. All rights reserved.
关键词:
polypyrrole coatings;stainless steel;HCl solution;corrosion;electrochemistry;acid sulfate-solutions;pem fuel-cell;mild-steel;films;behavior;electrochemistry;resistance;iron
Journal of Physics and Chemistry of Solids
La1-xCaxCrO3 (x = 0.0-0.5) samples were prepared by the sol-gel method. The sintering temperature of the samples can decrease to 1573 K. The crystal structures of La1-xCaxCrO3 at room temperature all are of the orthorhombic perovskite GdFeO3-type. XPS analysis indicates that the chromium ions are in a mixed valence state. The introduction of Ca2+ into the lattice is compensated by the oxidation of Cr3+ to Cr6+. With increasing x, the amount of Cr6+ increases. The presence of Cr6+ is one of the key factors affecting the electrical conductivity of La1-xCaxCrO3. (C) 2001 Published by Elsevier Science Ltd.
关键词:
ceramics;photoelectron spectroscopy;electrical conductivity
Journal of Physical Chemistry C
The highly unusual structural and electronic properties of the alpha-phase of (Si(1-x)C(x))(3)N(4) are determined by density functional theory (DFT) calculations using the Generalized Gradient Approximation (GGA). The electronic properties of alpha-(Si(1-x)C(x))(3)N(4) are found to be very close to those of alpha-C(3)N(4). The bandgap of alpha-(Si(1-x)C(x))(3)N(4) significantly decreases as C atoms are substituted by Si atoms (in 2 most cases, smaller than that of either alpha-Si(3)N(4) or alpha-C(3)N(4)) and attains a minimum when the ratio of C to Si is close to 2. On the other hand, the bulk modulus of alpha-(Si(1-x)C(x))(3)N(4) is found to be closer to that of alpha-Si(3)N(4) than of alpha-C(3)N(4). Plasma-assisted synthesis experiments of CN(x) and SiCN films are performed to verify the accuracy of the DFT calculations. TEM measurements confirm the calculated lattice constants, and FT-IR/XPS analysis confirms the formation and lengths of C-N and Si-N bonds. The results of DFT calculations are also in a remarkable agreement with the experiments of other authors.
关键词:
chemical-vapor-deposition;silicon-carbon nitride;thin-films;optical-properties;room-temperature;alpha-phase;growth;hard;photoluminescence;microstructure
Materials and Corrosion-Werkstoffe Und Korrosion
A CrN/Cr(1-x)Al(x)N coating comprised of an inner layer of CrN and an outer layer of Cr1(1-x)Al(x)N with a gradient distribution of Al was deposited on two different alloys by a reactive sputtering method. Oxidation and hot-corrosion tests of the gradient CrN/Cr1(1-x)Al(x)N coating were performed at different temperatures. The phase compositions and morphologies of the as-deposited coating and the corrosion products were investigated by using XRD and SEM/EDS. The results showed that the gradient CrN/Cr1(1-x)Al(x)N coating exhibited good oxidation resistance at temperatures above 1000 degrees C owing to the formation of an alpha-Al(2)O(3)-rich oxide scale. The coating possessed good hot-corrosion resistance in molten sulfate because the inner CrN layer could supply enough Cr to form a relatively protective Cr(2)O(3) after the Al(2)O(3)-enriched scale failed due to its dissolution in the molten sulfate.
关键词:
high-temperature oxidation;aluminide coatings;overlay coatings;nitride coatings;behavior;alloy;superalloy;k38g;cr
Electrochimica Acta
To investigate the corrosion protection mechanism of polyaniline (PANI) films on ferrous metals, this work presents preparation method of a separate protonated PANI film electrode and results of its open-circuit potential (OCP) in 0.5 M NaClO4 and 0.5 M Na2SO4 solutions with different pH and the galvanic interaction between the PANI film electrode and ferrous metals. X-ray photoelectron spectroscopy (XPS) shows the lower pH corresponds to higher protonation level of H+ in the film, and a more positive OCP of PANI film. The PANI film accelerated the corrosion of 20A carbon steel slightly with a PANI to steel area ratio less than 25: 1, while the PANI films maintained passivity for a ratio above to 25:1 for the 20A steel. For the coupling of 2Cr13 stainless steel/PANI, an equal area PANI film could maintain 2Cr13 in a passive state. The results suggest that corrosion protection of 20A carbon steel and 2Cr13 stainless steel by PANI film in the acid solution is due to passivity protection. The excess oxidative charge stored in the PANI and the equilibrium activity of protonated PANI with the acid environment provide a persistent driving force for carbon steel and 2Cr13 stainless steel passivity. (C) 2004 Elsevier Ltd. All rights reserved.
关键词:
protonated polyaniline;ferrous metals;open-circuit potential;galvanic;coupling;passivity;corrosion protection;mild-steel;coatings;behavior
Materials and Corrosion-Werkstoffe Und Korrosion
In order to investigate the galvanic anodic protection (GAP) of ferrous metals (such as 410, 304 and 316 stainless steels) in acid solutions by doped polyaniline (PANi), separate doped PANi powder-pressed electrodes with different surface areas (the area ratio of the PANi electrode to stainless steel is between 1:1 and 1:2) have been prepared. These were coupled with ferrous metal in the following solutions: 5 M sulphuric acid, 5 M phosphoric acid and industrial phosphoric acid (containing 5 M phosphoric acid and 0.05% chloride ion) to construct a galvanic cell, in which PANi is cathode while ferrous metal is anode. The results indicate that a PANi electrode with sufficient area can provide corrosion protection to stainless steel in these acidic solutions. A pilot scale coupling experiment was carried out. The results indicate that PANi is a promising material as an electrode for the anodic protection of ferrous metals in acidic solutions in industrial situations.
关键词:
conducting polymer-coatings;corrosion protection;stainless-steel;spectroscopy;passivation;performance;mechanism;behavior;primers;films
