YU Fanghua YANG Guohua Shanghai Institute of Nuclear Research
,
Academia Sinica
,
Shanghai
,
ChinaHAN Rongdian WENG Huimin University of Science and Technology of China
,
Hefei
,
ChinaSHEN Jianian Corrosion Science Laboratory
,
Institute of Corrosion and Protection of Metals Academia Sinica
,
Shenvang
,
China
金属学报(英文版)
The effects of small amount(≥0.05%)of active elements Y and Ce in Fe-25Cr-40Ni al- loy have been investigated on the kinetics of early stage of high temperature oxidation as well as composition and microsructure of oxide film by ion backscattering and slow positron beam.The results show that Y and Ce can reduce evidently the high tem- perature oxidation rate of FeCrNi alloy at early stage and can effectively enhance the Cr_2O_3 formation and retard the oxide formation of Fe and Ni in the surface layer thus the microstructure of the oxide film is improved.Y and Ce enter the oxide film and concentrate within several tens nanometres from surface of the outer layer.The mech- anism of oxidation resistance for Ce is different from Y.Ce can decrease the density of vacancy defects in oxide layer,so the cations are restrained from diffusion outward through vacancies.While Y can control the outward diffusion of cations through va- cancies at the early statge of oxidation(shorter than 12 min),aften that restrained the cations from diffusion outward along grain boundaries up to 60 min oxidation.
关键词:
ion backscattering
,
null
,
null
,
null
,
null
MA Zongyi YAO Zhongkai Harbin Institute of Technology
,
Harbin
,
China
金属学报(英文版)
The SiC_w/Al composite prepared by squeeze casting has a combination of superior room temperature specific strength and modulus together with excellent thermal properties.The extrusion can make an improvement on the strength and ductility of the composite from 582 MPa as squeeze casted up to 639 MPa,and on the transformation from isotropic to the anisotropic structure.This seems to be explained by the orientation of whiskers and the densification of dislocations in matrix.TEM observation indicates that the stacking fault is the usual planar defect on the SiC_w surface. composite;;SiC whisker;;Al alloy;;microstructure
关键词:
composite
,
null
,
null
,
null
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
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
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
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
