E. Cano

Copper corrosion inhibition by triphenylmethane derivatives in sulphuric acid media

Triphenylmethane derivatives, namely fuchsin basic (FB) and fuchsin acid (FA), were studied for their possible use as copper corrosion inhibitors in 0.001 to 1.0 M sulphuric acid solutions. Benzotriazole (BTA) was also tested for comparative purposes. These inhibitors were studied in concentrations from 1×10−5 to 1×10−1 M at temperatures from 298 to 328 K. The gravimetric method was employed to study the protective effect of FB, FA and BTA. The order of inhibition efficiency was BTA>FB>FA. Up to nine adsorption isotherms were tested to fit the experimental data. The best fit was obtained using the Frumkin isotherm model. A thermodynamic/kinetic model of adsorption was also fitted. The projected molecular area of the inhibitors was calculated to elucidate inhibitor orientation in the adsorption process.

Influence of pH and oxygen on copper corrosion in simulated uterine fluid.

This paper studies the copper corrosion in simulated uterine fluids in the presence of urea and/or albumin, at pH 5.0, 6.3 and 8.0, with 0.10, 0.15 and 0.20 atmospheres of oxygen pressure and without additional oxygen pressure, at 37 degrees C temperature, and for 1, 3, 7, 15, 21 and 30 days experimentation. The copper dissolution rate was determined using absorbance measurements. Copper dissolution was the highest at pH 8.0 and 0.20 atmospheres of oxygen pressure, 674 microg d(-1) for 1 day and 109 microg d(-1) for 30 days. The presence of albumin, contrary to urea, accelerates copper corrosion.

An XPS study of copper corrosion originated by formic acid vapour at 40% and 80% relative humidity

Copper corrosion products originated by the action of formic acid vapours at 40% and 80% relative humidity for a period of 21 days were analysed. Three formic vapour concentration levels (10, 100 and 300 ppm) were generated in laboratory tests at 30°C. The corrosion product layers were characterised using X-ray photoelectron spectroscopy (XPS) in conjunction with Ar+-ion sputtering. The components identified in the patina layers were cuprite (Cu2O), copper hydroxide (Cu(OH)2) and copper formate (Cu(HCOO)2). Copper formate was formed by a complex mechanism including copper hydroxide and formic acid. Untersuchungen zur Korrosion von Kupfer durch Ameisensauredampfe bei einer relativen Luftfeuchtigkeit zwischen 40 und 80% mit Hilfe der fotoelektronischen Rontgenspektroskopie XPS In der vorliegenden Arbeit werden die auf Kupfer durch Einwirkung von Ameisensauredampfen wahrend eines Zeitraums von 21 Tagen bei einer relativen Luftfeuchtigkeit zwischen 40% und 80% gebildeten Korrosionsprodukte untersucht. In Laborversuchen wurden bei einer Temperatur von 30°C Ameisensauredampfe mit Konzentrationen von 10, 100 und 300 ppm erzeugt. Die Untersuchung der Korrosionsprodukte erfolgte mit der fotoelektronischen Rontgenspektroskopie (XPS) zusammen mit einem Abtrag durch Argon-Ionen. Es wurden folgende Verbindungen festgestellt: Rotes Kupferoxid (Cu2O), Kupferhydroxid (Cu(OH)2) und Kupferformiat (Cu(HCOO)2). Das Kupferformiat bildete sich in einem komplexen Prozes unter Beteiligung von Kupferhydroxid und Ameisensaure.

Copper corrosion-simulated uterine solutions.

We studied the copper corrosion and product layers originating in a simulated uterine solution at pH values 6.3 and 8.0 for 15, 65, 180, and 360 days at 37 degrees C. Absorbance measurements were performed. Corrosion product layers on the copper surface were characterized by scanning electron microscopy, energy dispersive x-ray, and x-ray photo-electron spectroscopy techniques. Copper release for pH 6.3 and 8.0 was 3.4-4.5 microg/day for 15 days and 0.1-0.3 microg/day for 360 days. Of the order of 30%-40% of dissolved cupric ions were trapped in the product layers. The main compounds identified were cuprite (Cu(2)O), calcite (CaCO(3)), and phosphates.

Influence of molybdenum on passivation of polarised stainless steels in a chloride environment

Abstract Polarised specimens of AISI 304L and 316L stainless steels (SS) were studied using X-ray photoelectron spectroscopy in conjunction with Ar+-ion sputtering. A 5% NaCl test solution was used at room temperature. The polarised passive films formed consist mainly of chromium oxide and hydroxide and a small proportion of iron oxides. The composition of the films depend strongly on the potential. Chloride and molybdenum ions appear when the AISI 316L SS alloy is polarised at a potential close to pitting potential.

Corrosion of Copper and Lead by Formaldehyde, Formic and Acetic Acid Vapours

Abstract The formation of corrosion products and the corrosion sensitivity of copper and lead were studied under experimental conditions in which formaldehyde (methanal), formic (methanoic) and acetic (ethanoic) acid concentration, relative humidity (RH) and duration of exposure were varied. Levels offormic acid above 0.4 parts per million based on volume (ppmv) affect the appearance of copper at 75% RH, and at levels above 4 ppmv the copper gains weight at both 54 and 75% RH. The main compound found on copper was cuprite, copper(I) oxide. Lead has a higher sensitivity to formic acid: at levels as low as 0.04 ppmv lead becomes darker, and at above O.1 ppmv weight gains were measurable at both 54 and 75% RH. In the presence of different levels of mixed carbonyl vapours at 75% RH, copper reacted mainly with formic acid. On the other hand, the reaction of lead was more complex. Acetic acid tends to form a thick white layer (composed mainly of plumbonacrite and possibly lead acetate compounds) on the lead surface, while formic acid tends to form a rather thin and darker layer of lead formate hydroxide. In the presence of formic acid, the action of acetic acid on lead was inhibited. At levels of formaldehyde up to 3 ppmv, no significant contribution of formaldehyde to the corrosion process on lead and copper was observed.

Corrosion protection properties of cerium layers formed on tinplate

Abstract Corrosion protection properties of cerium-passivated, unpassivated and chromium-passivated tinplates in contact with a 0.1 M citric-citrate buffer solution were studied using polarisation (DC) and electrochemical impedance spectroscopy (EIS) methods. The morphology and composition of the passive layer were studied using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS) in conjunction with argon-ion sputtering. Cerium-passivated tinplate showed similar corrosion properties to chromium-passivated tinplate in DC measurements, while the latter yielded the best corrosion resistance results in EIS measurements. SEM and EDX illustrated spherical particles with iron, cerium and tin contributions. XPS measurements indicated that the cerium-rich coating was a hydrated oxide with a composition of cerium(III): Ce(OH) 3 and cerium(IV): CeO 2 and Ce(OH) 4 .

Substitutional inhibition mechanism of mild steel hydrochloric acid corrosion by hexylamine and dodecylamine

Hexylamine and dodecylamine were investigated as inhibitors of mild steel hydrochloric acid corrosion, in concentrations from 1 × 10−6 to 1.0 M, at a temperature of 298 K. For a given inhibitor concentration, dodecylamine showed higher effectiveness than hexylamine. The inhibitor mechanism was treated as a substitutional adsorption process according to Flory–Huggins (FH), Dhar–Flory–Huggins (DFH) and Bockris–Swinkels (BS) isotherms. The best approach was obtained using FH and DFH isotherms, with one molecule of inhibitor replacing three molecules of water. A structural parameter, the projected molecular area of these two inhibitors, was calculated to elucidate inhibitor orientation in the adsorption process.

Effect of NaCl priming on increased salt tolerance in tomato

SummaryTomato seeds (Lycopersicon esculentum Mill.) cvs Pera, Muchamiel, P-73 and GC-72, were primed with 0,0.5 and 1.0 M NaCl solutions. The plants were then grown at 35,70 and 140 mM NaCl. These salt treatments were applied pre-emergence (seed sowing) and post-emergence (4 leaf stage). The effect of seed priming on yield was different depending on both the NaCl concentration used for seed priming and on the time of starting the salt treatments during the growing period of the plants. The yield increase under 1.0 M NaCl priming was mainly due to increased fruit weight, but was always reduced by increasing the NaCl treatment (35-140 mM). The effect of this seed priming on yield was higher when salt treatments were applied pre- rather than post-emergence, although it was significant only in plants treated at 35 and 70 mM NaCl. At pre-emergence, the yield increased in cvs Pera, Muchamiel and GC-72, whereas at post-emergence only cv. GC-72 increased its yield by salt priming. The increase in yield of cv. GC-...

An impedance study on the influence of molybdenum in stainless steel pitting corrosion

Abstract Impedance measurements were made for AISI 304L and 316L stainless steels in a 5% NaCl solution at room temperature. Nyquist plots in the pitting potential region show three loops: a capacitive loop at high frequencies; a loop with inductive effects at intermediate frequencies; and a second capacitive response at low frequencies. An equivalent electrical circuit has been proposed to model the AISI 304L and 316L SS/NaCl systems. Negative capacitance and resistance were obtained. The impedance data do not satisfy Kramers–Kronig (KK) transforms. Details of the KK determinations are included.