共查询到20条相似文献,搜索用时 31 毫秒
1.
Viviane Dalmoro Jo?o H. Z. dos Santos Denise S. Azambuja 《Journal of Solid State Electrochemistry》2012,16(1):403-414
Protection from corrosion of the aluminum alloy AA2024-T3 coated with a tetraethoxysilicate (TEOS)/aminotrimethyllenephosphonic
acid (ATMP) film in a 0.05-mol L−1 NaCl solution was evaluated using electrochemical impedance spectroscopy, scanning electron microscopy, energy disperse spectroscopy,
and atomic force microscopy. The present work investigates the influence of different pretreatment procedures of the alloy
surface and the ATMP concentration on the corrosion resistance of the coated samples. The undoped sol–gel coatings did not
provide adequate corrosion protection. The best corrosion protection was achieved using acetic acid pretreatment and subsequent
deposition of an ATMP-modified TEOS film with an optimal concentration of 5.00 × 10−4 mol L−1 in the deposition bath. The acetic acid pretreatment promotes a decrease in galvanic corrosion and the surface enrichment
of aluminum favoring the metalosiloxane and the metal–phosphonic bonds with increasing likely reaction sites, thus promoting
the formation of a more homogeneous and compact coating with improved resistance. 相似文献
2.
The corrosion behavior and surface morphology of Ni–SiC composite coatings produced by electrodeposition with the aid of magnetic
field were studied. The results of the electrochemical analysis including polarization resistance and potentiodynamic polarization
curves showed that a magnetic field of 0.1 T could significantly improve the corrosion resistance of the composite. The electrochemical
impedance spectra revealed that a passive layer was formed on the surface of the Ni–SiC coating with the magnetic field. The
microstructures of electrodeposited Ni–SiC composite coatings were also examined. More SiC particles were found to be incorporated
into the coating with the presence of magnetic field, which was considered to be one of the reasons for the enhancement of
corrosion resistance as SiC particles were reported to be corrosion inhibitors.
Contribution to special issue “Magnetic field effects in Electrochemistry” 相似文献
3.
Alexandra Wittmar Matthias Wittmar Alfred Ulrich Hinka Caparrotti Michael Veith 《Journal of Sol-Gel Science and Technology》2012,61(3):600-612
The protective capabilities of sol–gel coatings are determined by their physical barrier properties. For an effective protection,
a homogenous crack-free material is required, which prevents from attacks of corrosive species. When the coating is damaged,
active corrosion protection is usually achieved by the use of inhibitors. Among the different inhibitors rare earth ions and
especially cerium have shown effective inhibiting properties. Due to the complexity of the corrosion processes, a combination
of inhibitors is expected to be superior to a monocomponent inhibiting. The aim of this study was to prove which other ions,
used in combination with cerium, can improve the corrosion protection abilities of hybrid silica based inorganic–organic sol–gel
coatings applied on aluminium alloy 2024 substrates. Mixtures of cerium nitrate with two other potential inhibitor substances
were incorporated into a sol–gel matrix and their behaviour in neutral salt spray test and during EIS measurements was investigated.
The Ce–P–Pr inhibitor combination (Ce3+, PO4
3−, Pr3+) has shown the best long-term corrosion protection properties at low doping levels. 相似文献
4.
Hiroyuki Shinomiya Zenta Kato Koji Hashimoto 《Journal of Solid State Electrochemistry》2009,13(2):293-299
Rod-shaped amorphous bulk Ni–Cr–Mo-22 at.%Ta-14 at.%Nb–P alloys resistant to concentrated hydrochloric acids were prepared
by copper-mold casting. Alloys of amorphous single phase and mixture of nanocrystalline phases in the amorphous matrix were
all spontaneously passive in 6 and 12 M HCl and were immune to corrosion in 6 M HCl, although the corrosion weight loss was
detected for heterogeneous alloys in 12 M HCl. Spontaneous passivation is due to presence of stable air-formed films in which
chromium was particularly concentrated in addition to enrichment of tantalum and niobium. The angle resolved X-ray photoelectron
spectroscopy revealed that chromium and molybdenum are rich in the inner part of the film. The major molybdenum species is
in the tetravalent state, although penta- and hexavalent state molybdenum is also included. The high corrosion resistance
was interpreted in terms of the high stability of the outer triple oxyhydroxide, Cr1−x−yTaxNbyOz(OH)3+2x+2y−2z, and the effective diffusion barrier of the inner Mo4+ and Cr3+ oxide layer.
Contribution to the Fall Meeting of the European Materials Research Society, Symposium D: 9th International Symposium on Electrochemical/Chemical
Reactivity of Metastable Materials, Warsaw, 17th-21st September, 2007. 相似文献
5.
Eugenijus Norkus Algirdas Vaškelis Irena Stalnioniene 《Journal of Solid State Electrochemistry》2000,4(6):337-341
The surface area (nanoscale roughness) of copper coatings deposited from electroless plating solutions containing Quadrol,
L(+)- and DL(∓)-tartrate as Cu(II) ion ligands was measured using underpotential deposition thallium monolayer formation.
Surface roughness of Cu coatings depends on the plating solution pH and the Cu(II) ligand, and varies over a wide range. In
L(+)-tartrate and Quadrol solutions (pH 12.5–13.3) the roughness factor R
f is low and is equal to 2–3 and 4–6, respectively (substrate: electrodeposited Cu; R
f=2.2). Cu coatings of higher surface area are obtained in DL(∓)-tartrate (pH 12.3–12.7) and Quadrol (pH 12.0) solutions: R
f reaches 20–30. The correlation between R
f and Cu deposition rate was found in L(+)-tartrate solution. The Cu surface area changes are discussed in terms of partial
electrochemical reactions of the autocatalytic Cu deposition process, and the decisive role of cathodic Cu(II) reduction from
adsorbed Cu(II) complex species.
Received: 2 November 1999 / Accepted: 22 February 2000 相似文献
6.
A highly sensitive hydroxylamine (HA) electrochemical sensor is developed based on electrodeposition of gold nanoparticles
with diameter of 8 nm on the pre-synthesized polypyrrole matrix and formed gold nanoparticles/polypyrrole (GNPs/PPy) composite
on glassy carbon electrode. The electrochemical behavior and electrocatalytic activity of the composite-modified electrode
are investigated. The GNPs/PPy composite exhibits a distinctly higher electrocatalytic activity for the oxidation of HA than
GNPs with twofold enhancement of peak current. The enhanced electrocatalytic activity is attributed to the synergic effect
of the highly dispersed gold metal particles and PPy matrix. The overall numbers of electrons involved in HA oxidation, the
electron transfer coefficient, catalytic rate constant, and diffusion coefficient are investigated by chronoamperometry. The
sensor presents two wide linear ranges of 4.5 × 10−7–1.2 × 10−3 M and 1.2 × 10−3–19 × 10−3 M with the detection limit of 4.5 × 10−8 M (s/n = 3). In addition, the proposed electrode shows excellent sensitivity, selectivity, reproducibility, and stability properties. 相似文献
7.
Austempered ductile iron (ADI) has complex microstructure containing a multiphase matrix (called ‘ausferrite’), graphite spheres
and oxide inclusions. The corrosion resistance of ADI is related to its microstructure which is determined by heat treatment
parameters (like austempering temperature, austempering time, austenitising temperature and austenitising time). In the present
paper, the electrochemical behaviour and corrosion resistance of ADI have been investigated by means of the electrochemical
microcell technique and classical electrochemical measurements in sodium chloride solution. Particular attention has been
paid to the influence of austempering temperature on the microstructure and pitting corrosion. It has been shown that ADI
austempered at 430 °C has upper ausferritic microstructure and reveals a better corrosion resistance in sodium chloride solution
than ADI austempered at 280 °C. Moreover, the corrosion resistance increases as the volume fracture of ferrite increases and
the carbon content of austenite decreases. The good corrosion behaviour of ADI austempered at 430 °C was also related to the
good coarsening of the austenite grains and broad ferrite needles (less ferrite/austenite interfaces). It has been demonstrated
that silicon is the alloying element hindering the anodic dissolution of the alloy. 相似文献
8.
L. M. M. dos Santos M. M. Lemos Salta I. T. E. Fonseca 《Journal of Solid State Electrochemistry》2007,11(2):259-266
This paper reports a voltammetric study of bronze in synthetic seawater (SSW). The effects of buffering and deoxygenating were particularly visible in the transpassive region. The breakdown of the anodic passive film on bronze leads to a well-defined activation peak in the transpassive region typical of a nucleation and growth of pits. The breakdown potential of the passivity was shown to vary with the experimental conditions, namely, with buffering and deoxygenating. Buffering has shown to lead to more stable passive films and deoxygenating to higher oxidation currents. Scanning electron microscopy with energy dispersive spectrometer (SEM/EDS) studies of bronze samples with 1-month exposure in non-deoxygenated buffered and non-buffered SSW under open circuit potential have shown significant differences in their morphology: a uniformly cracked surface and a surface showing large and spherical precipitates of about 50 μm uniformly distributed along the surface, respectively, for bronze coupons in buffered (pH 9) and in non-buffered SSW. The EDS technique has identified Cu, O, Cl and Na on the corrosion products of bronze in non-buffered SSW, whilst in buffered media, Sn was also identified. In non-buffered media, open circuit potentials have shown to be all the time less negative than in the buffered media. After 1-month exposure the E
OCP of bronze samples in both media seem to converge to −0.131 and −0.155 V vs Ag|AgCl, respectively. This potential can be assigned to the formation of cuprite, Cu2O and nantokite, CuCl. The analysis of the SEM images after the removal of the corrosion products has shown descuprification with higher intensity on the surface from coupons in non-buffered SSW. 相似文献
9.
The electrochemical behavior of the ofloxacin–copper complex, Cu(II)L2, at a mercury electrode, and the interaction of DNA with the complex have been investigated. The experiments indicate that
the electrode reaction of Cu(II)L2 is an irreversible surface electrochemical reaction and that the reactant is of adsorbed character. In the presence of DNA,
the formation of the electrochemically non-active complexes Cu(II)L2-DNA, results in the decrease of the peak current of Cu(II)L2. Based on the electrochemical behavior of the Cu(II)L2 with DNA, binding by electrostatic interaction is suggested and a new method for determining nucleic acid is proposed. Under
the optimum conditions, the decrease of the peak current is in proportional to the concentration of nucleic acids in the range
from 3 × 10−8 to 3 × 10−6 g · mL−1 for calf thymus DNA, from 1.6 × 10−8 to 9.0 × 10−7 g · mL−1 for fish sperm DNA, and from 3.3 × 10−8 to 5.5 × 10−7 g · mL−1 for yeast RNA. The detection limits are 3.3 × 10−9, 6.7 × 10−9 and 8.0 × 10−9 g · mL−1, respectively. The method exhibits good recovery and high sensitivity in synthetic samples and in real samples. 相似文献
10.
Y. Hatano R. Hitaka M. Sugisaki M. Hayashi 《Journal of Radioanalytical and Nuclear Chemistry》1999,239(3):445-448
The diffusion behavior of hydrogen in the oxide films of zircaloy-4 specimens containing different size of Zr(Fe,Cr)2 precipitates was examined. In the case of the specimen containing fine precipitates, hydrogen diffused uniformly through
the zirconium oxide phase. The diffusion coefficient was 2·10−21 m2·s−1 at room temperature and 6·10−19 m2·s−1 at 673 K. The transport rate of hydrogen in the oxide film of the specimen containing coarse precipitates was significantly
higher than that of the specimen containing fine ones at both room temperature and 673 K. 相似文献
11.
Andrzej Królikowski Ewelina Płońska Andrzej Ostrowski Mikołaj Donten Zbigniew Stojek 《Journal of Solid State Electrochemistry》2009,13(2):263-275
Ni–W alloys were electrodeposited onto copper foil from citrate solution. Coatings containing from 11 to 21 at.% W and having
7–52 μm in thickness were obtained. The structure of these alloys was analyzed by X-ray diffraction and by using electron
and light microscopy techniques. Alloys with 11 and 15% W are composed of two phases: solid solution of W in fcc Ni and solid
solution of Ni in bcc W. An increase in W content in the Ni–W alloys to ca. 18–19% of W resulted in the grain refinement and
the transition to amorphous structure. The corrosion behavior of obtained Ni–W and unalloyed Ni coatings was studied in 0.5 M
NaCl solution by means of electrochemical impedance spectroscopy, potentiodynamic polarization and light microscopy. Comparing
to pure Ni, the obtained Ni–W coatings exhibited a clearly decreased corrosion resistance (in terms of corrosion current density
and polarization or charge transfer resistance at the open circuit potential). Despite of the quite wide range of composition
of the alloys under test, the related grain refinement, and the transition to the amorphous structure, no clear relation between
the corrosion rate and W content was detected. This behavior can be a result of the interplay of the activating effect of
grain refinement or preferential dissolution of W from one side and diffusion barrier action or inhibition provided by the
surface film of W oxidation products from the other side. The differences observed in the corrosion resistance of Ni–W coatings
are more related to their morphological imperfections arising from various deposition conditions than to the W content. Some
samples showed a rather non-uniform nature of corrosion (pronounced attack along cracks). An inversion in the dissolution
behavior of Ni–W and unalloyed Ni was observed with increasing anodic potential. Contrary to pure Ni, Ni–W coatings were resistant
to pitting corrosion in NaCl solution.
Contribution to the Fall Meeting of the European Materials Research Society, Symposium D: 9th International Symposium on Electrochemical/Chemical
Reactivity of Metastable Materials, Warsaw, 17th–21st September, 2007. 相似文献
12.
S. A. Umoren 《Cellulose (London, England)》2008,15(5):751-761
The corrosion behaviour of mild steel and aluminium exposed to H2SO4 solution and their inhibition in H2SO4 containing 0.1–0.5 g/L Gum Arabic (GA) used as inhibitor was studied at temperature range of 30–60 °C using weight loss and
thermometric techniques. Corrosion rate increased both in the absence and presence of inhibitor with increase in temperature.
Corrosion rate was also found to decrease in the presence of inhibitor compared to the free acid solution. Inhibition efficiency
increases with increase in concentration of the inhibitor reaching a maximum of 37.88% at 60 °C for mild steel and 79.69%
at 30 °C for aluminium at 0.5 g/L concentration of GA. The inhibitor, GA was found to obey Temkin and El-Awady et al. thermodynamic
kinetic adsorption isotherm for mild steel and aluminium respectively from the fit of the experimental data at all concentrations
and temperatures studied. The phenomenon of chemical adsorption is proposed for mild steel corrosion, while physical adsorption
mechanism is proposed for aluminium corrosion. Results obtained for the kinetic/thermodynamic studies indicate that the adsorption
of GA onto the metals surface was spontaneous. GA is a better corrosion inhibitor for aluminium than for mild steel. 相似文献
13.
Effects of exposure time on the anodic dissolution of Monel-400 in aerated stagnant sodium chloride solutions 总被引:1,自引:0,他引:1
El-Sayed M. Sherif 《Journal of Solid State Electrochemistry》2012,16(3):891-899
The anodic dissolution of Monel-400 (63.0% Ni, 28–34% Cu) alloy after its immersion in freely aerated stagnant 3.5% NaCl solutions
for 0, 24, and 72 h has been investigated. The study was carried out using a variety of electrochemical techniques and gravimetric
measurements after varied exposure periods (5–160 days). The work was complemented by scanning electron microscopy and energy
dispersive X-ray analyzer (SEM/EDX) investigations. The electrochemical measurements showed that Monel suffers both general
and pitting corrosion. The severity of uniform corrosion decreased, while pitting one increased with increasing the immersion
time to 24 h and further to 72 h before measurements. Gravimetric data indicated that the weight loss increased, while the
corrosion rate decreased for Monel with time. SEM images and EDX profile analyses confirmed that the corrosion of Monel after
160 days immersion in NaCl solutions occurs due to the selective dissolution of nickel. 相似文献
14.
Luis A. Toledo-Matos Maximo Antonio Pech-Canul 《Journal of Solid State Electrochemistry》2011,15(9):1927-1934
The evolution under open-circuit conditions of iron passive films formed at 0.8 VSCE in a borate buffer solution at pH 8.4 was investigated with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry.
The composition of the freshly formed passive film as determined by X-ray photoelectron spectroscopy (XPS) was found to be
in agreement with a bilayer model, where the inner layer is composed mainly of iron oxide and the outer layer consists of
a hydrated material. Results of XPS measurements also showed that the open-circuit breakdown of passive films was consistent
with a reductive dissolution mechanism. When the iron electrode reached an intermediate stage in the open-circuit potential
decay (approximately −0.3 VSCE), the oxide film, containing both Fe(II) and Fe(III), was still protective. The impedance response in this stage exhibited
a mixed control by charge transfer at the metal/film and film/solution interfaces and diffusion of point defects through the
film. At the final stage of the open-circuit potential decay (approximately −0.7 VSCE), the oxide film was very thin, and the ratio of Fe3+/Fe2+ and O2−/OH− had decreased significantly. The impedance response also exhibited a mixed charge-transfer–diffusion control, but the diffusion
process was related to transport of species in the electrolyte solution resulting from dissolution of the oxide film. 相似文献
15.
A.K. Singh Puja Saxena Amit Panwar 《Journal of inclusion phenomena and macrocyclic chemistry》2006,54(3-4):299-305
Copper (II) complex of 2,4-dimethyl-1,5,9,12-tetraazacyclopentadeca-1,4-diene, [Me2(15)dieneN4] was synthesized and used in the fabrication of Cu2+ – selective ISE membrane in PVC matrix. The membrane having Cu(II) macrocyclic complex as electroactive material along with sodium tetraphenyl borate (NaTPB) as anion discriminator. Dibutyl phthalate (DBP) as plasticizer in poly(vinyl chloride) (PVC) matrix was prepared for the determination of Cu2+. The best performance was observed by the membrane having Cu(II) complex–PVC–NaTPB–DBP with composition 1:5:1:3. The sensor worked well over a concentration range 1.12 × 10−6 M–1.0 × 10−1 M between pH 2.1–6.2 and a fast response time 10±2 s and a lifetime of 6 months. Their performance in partially non-aqueous medium was found satisfactory. Electrodes exhibited excellent selectivity for Cu2+ ion over other mono-, di-, trivalent cations. It can also be used as indicator electrode in the potentiometric titration of Cu2+ against EDTA as well as in the determination of Cu2+ in real samples. 相似文献
16.
The effect of different Cu addition on the electrochemical and passivation behaviour of the 304 series stainless steel in 0.1 M phosphoric acid solution was evaluated by the potentiodynamic measurements and electrochemical impedance spectrum (EIS). The effect of Cu on chemical composition of the passive film formed in the solution was also studied by X‐ray photoelectron spectroscopy (XPS). The results indicated that Cu did not appreciably improve the corrosion resistance of the passive film, but enhanced the passivation, lowered the critical and passive current density. The passive and critical current density decreased with Cu content increased. The presence of Cu in the passive film affects passive film stability. Cu can modify the proportion of Cr element in the passive film, and also change the components of Fe in the passive film. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
17.
Annibaldi A Truzzi C Illuminati S Bassotti E Scarponi G 《Analytical and bioanalytical chemistry》2007,387(3):977-998
Eight PM10 aerosol samples were collected in the vicinity of the “Mario Zucchelli” Italian Antarctic Station (formerly Terra
Nova Bay Station) during the 2000–2001 austral summer using a high-volume sampler and precleaned cellulose filters. The aerosol
mass was determined by differential weighing of filters carried out in a clean chemistry laboratory under controlled temperature
and humidity. A two-step sequential extraction procedure was used to separate the water-soluble and the insoluble (dilute-HCl-extractable)
fractions. Cd, Pb and Cu were determined in the two fractions using an ultrasensitive square wave anodic stripping voltammetric
(SWASV) procedure set up for and applied to aerosol samples for the first time. Total extractable metals showed maxima at
midsummer for Cd and Pb and a less clear trend for Cu. In particular, particulate metal concentrations ranged as follows:
Cd 0.84–9.2 μg g−1 (average 4.7 μg g−1), Pb 13.2–81 μg g−1 (average 33 μg g−1), Cu 126–628 μg g−1 (average 378 μg g−1). In terms of atmospheric concentration, the values were: Cd 0.55–6.3 pg m−3 (average 3.4 pg m−3), Pb 8.7–48 pg m−3 (average 24 pg m−3), Cu 75–365 pg m−3 (average 266 pg m−3). At the beginning of the season the three metals appear widely distributed in the insoluble (HCl-extractable) fraction (higher
proportions for Cd and Pb, 90–100%, and lower for Cu, 70–90%) with maxima in the second half of December. The soluble fraction
then increases, and at the end of the season Cd and Pb are approximately equidistributed between the two fractions, while
for Cu the soluble fraction reaches its maximum level of 36%. Practically negligible contributions are estimated for crustal
and sea-spray sources. Low but significant volcanic contributions are estimated for Cd and Pb (∼10% and ∼5%, respectively),
while there is an evident although not quantified marine biogenic source, at least for Cd. The estimated natural contributions
(possibly including the marine biogenic source) cannot account for the high fractions of the metal contents, particularly
for Pb and Cu, and this suggests that pollution from long-range transport is the dominant source.
Figure Aerosol sampling in Antarctica 相似文献
18.
In this paper, an electrochemical investigation of (−)-epigallocatechin gallate (EGCG) and its interaction with DNA is presented.
Via an electrochemical approach assisted by ultraviolet–visible (UV–Vis) spectroscopy, we propose that EGCG can intercalate
into DNA strands forming a nonelectroactive complex, which results in the decrease of the anodic peak current of EGCG. Meanwhile,
an electrochemical study with the DNA–Cu(II)–EGCG system shows that damage to DNA can be recognized electrochemically via
the increase in the anodic peak current resulting from the oxidation of guanine and adenine bases. The damage can also be
recognized spectrophotometrically via an increase in the 260 nm absorption band. In addition, it was found that EGCG is able
to discriminate dsDNA from ssDNA, making a potential electrochemical indicator for the detection of DNA hybridization events.
A rapid and convenient method of detecting EGCG was also developed in this work.
Figure Interaction of EGCG with DNA and damage to DNA in the presence of Cu(II)
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
19.
A novel L-cysteine film modified electrode has been fabricated by means of an electrochemical oxidation procedure, and it
was successfully applied to the electrochemical determination of acetaminophen. This method utilizes the electrooxidation
of amines to their analogous cation radicals to form a chemically stable covalent linkage between the nitrogen atom of the
amine and edge plane sites at the glassy carbon electrode surface. The electrochemical behaviour of acetaminophen at the film
electrode was investigated in 0.1 mol L−1 phosphate buffer (pH 6.20). It was found that the redox peak current of acetaminophen was enhanced greatly on the film electrode.
Linearity between the oxidation peak current and the acetaminophen concentration was obtained in the range of 1.0 × 10−4–2.0 × 10−7 mol L−1 with a detection limit of 5.0 × 10−8 mol L−1. For seven parallel detections of 1.0 × 10−5 mol L−1 acetaminophen, the relative standard deviation (RSD) was 1.46%, suggesting that the film electrode has excellent reproducibility.
Application to the determination of acetaminophen in drug tablets and human urine demonstrated that the film electrode has
good stability and high sensitivity. 相似文献
20.
J. G. Gonzalez-Rodriguez M. Gonzalez-Castañeda M. Cuellar-Hernández G. Domínguez-Patiño G. Rosas 《Journal of Solid State Electrochemistry》2008,12(6):707-713
The corrosion behavior of FeAl-type intermetallic alloy in the Hank’s solution has been investigated after additions of 1,
3, and 5 at.% Ni with or without thermal annealing at 400 °C for 144 h. Techniques included potentiodynamic polarization curves,
linear polarization resistance, and change of the free corrosion potential with time and electrochemical noise in current.
Regardless of the heat treatment, additions of Ni increased both the free corrosion potential and the pitting potential values.
Additionally, both the corrosion current and the passive current densities were reduced with this element. The alloys which
did not suffer from pitting type of corrosion were the heat-treated FeAL base alloy and the one containing 5Ni. Both additions
of Ni and thermal annealing improved the adhesion of external protective layer either by avoiding the formation of voids or
by lowering the number of precipitates and making them more homogenously distributed. 相似文献