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Gonzalez-Rodriguez J. G. Casales M. Salinas-Bravo V. M. Espinosa-Medina M. A. Martinez-Villafañe A. 《Journal of Solid State Electrochemistry》2004,8(5):290-295
Electrochemical noise in current has been used to monitor the stress corrosion cracking (SCC) susceptibility of alloy 690 sensitized at 700 °C during 48 h in sodium thiosulfate at 90 °C. At 48 h of aging, the specimen failed by SCC and the corrosion current pulses had high intensity and low frequency, and were associated with the nucleation and propagation of stress corrosion cracks during slow strain rate tests. When the alloy was immune to SCC, the observed corrosion current pulses had a much higher frequency and lower intensity, indicating either uniform corrosion or passivation. The type of transients observed do not indicate the mechanism responsible for the observed embrittlement, but only the cracking initiation or propagation process. 相似文献
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U. León-Silva M. E. Nicho J. G. González-Rodríguez J. G. Chacón-Nava V. M. Salinas-Bravo 《Journal of Solid State Electrochemistry》2010,14(6):1089-1100
The effect of thermal annealing of poly(3-octylthiophene) (P3OT) coatings on the corrosion inhibition of stainless steel in
an NaCl solution was investigated. P3OT was synthesized by direct oxidation of the 3-octylthiophene monomer with ferric chloride
(FeCl3) as oxidant. P3OT films were deposited by drop-casting technique onto 304 stainless steel electrode (304SS). 304SS coated
with P3OT films were thermally annealed during 30 h at different temperatures (55°C, 80°C, and 100°C). The corrosion resistance
of stainless steel coated with P3OT in 0.5 M NaCl aqueous solution at room temperature was investigated by using potentiodynamic
polarization curves, linear polarization resistance, and electrochemical impedance spectroscopy. The results indicated that
the thermal treatment at 80°C and 100°C of P3OT films improved the corrosion resistance of the stainless steel in NaCl solution;
the speed of corrosion diminished in an order of magnitude with regard to the 304SS. In order to study the temperature effect
in the morphology of the coatings before and after the corrosive environment and correlate it with corrosion protection, atomic
force microscopy and scanning electron microscopy were used. Morphological study showed that when the films are heated, the
grain size increased and a denser surface was obtained, which benefited the barrier properties of the film. 相似文献
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V. M. Salinas-Bravo J. Porcayo-Calderon J. G. Gonzalez-Rodriguez 《Russian Journal of Electrochemistry》2006,42(5):560-565
Corrosion monitoring of different steels is carried out online in a combustion rig firing 32 kg/h of fuel oil. Two temperature-controlled
probes are designed to allow control of the specimens temperature and the use of electrochemical noise (EN) and linear polarization
resistance (LPR) techniques for corrosion monitoring. Two probes are placed where the combustion gas reached a temperature
of 850–900°C, and another one at the combustion gas exit where the rig was at 200–240°C. Corrosion rates of an austenitic
and a ferritic steel are obtained where the temperature of the combustion gas is 850–900°C, firing fuel oils with different
content of Na-V-S. Corrosion monitoring of mild steel is carried out in the test burning a fuel oil with the higher content
of Na-V-S by placing a corrosion probe in the low combustion gas temperature zone. The EN results show that this technique
is able to assess the corrosion rate in an environment at high temperature where fuel oil ashes deposited and at a temperature
high enough where they start to melt and a corrosion process proceeds. Results show that this technique is able to assess
the corrosivity of fuel oil ashes originated from fuel oil containing different amounts of sodium, vanadium, and sulfur as
corrosion causing impurities. Results of the low-temperature probe show that EN and LPR are able to detect the onset of corrosion
on mild steel as a result of sulfuric acid condensation on the probe. However, the corrosion rates are not the same, because
localized corrosion is taking place as detected by the EN technique. It is demonstrated that the use of two techniques for
corrosion monitoring can give a better understanding of the corrosion process. Electrochemical techniques used to assess the
corrosion resistance of alloys at high and low temperatures prove to be a valuable tool for the purposes of materials selection
or controlling the main process variables that affect the corrosion resistance of materials in industrial equipment.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 5, pp. 627–632.
The text was submitted by the authors in English. 相似文献
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