Corrosion Of Pure Iron Research Articles

Corrosion of iron in liquid uranium hexafluoride at 80 °C. Part I: Normal and abnormal experimental kinetics

The results reported here are the first on pure iron corrosion in liquid UF6 at 80 °C. Two kinetic behaviours have been observed: one led to micrometric scales (from micron to hundreds of microns after several months) and the other one to hundreds of nanometers for several months. The higher corrosion kinetics resulted in the presence of impurities such as NOxF complexes formed by interaction between the medium and the reactor material. These NOxF catalysed the corrosion reaction leading to a corrosion mechanism controlled by the cathodic reaction rate. Effect of impurities in UF6 coming from experimental conditions or nature of uranium ore should then be systematically and carefully checked. Whatever the corrosion kinetics and the presence of impurities, the nature of the layer was identical: a duplex fluoride scale composed of an iron rich layer, FeF2, and a uranium rich layer evolving over time from U2F9 to UF5.

Bioresorbable β-TCP-FeAg nanocomposites for load bearing bone implants: High pressure processing, properties and cell compatibility

In this paper, the processing and properties of iron-toughened bioresorbable β-tricalcium phosphate (β-TCP) nanocomposites are reported. β-TCP is chemically similar to bone mineral and thus a good candidate material for bioresorbable bone healing devices; however intrinsic brittleness and low bending strength make it unsuitable for use in load-bearing sites. Near fully dense β-TCP-matrix nanocomposites containing 30vol% Fe, with and without addition of silver, were produced employing high energy attrition milling of powders followed by high pressure consolidation/cold sintering at 2.5GPa. In order to increase pure iron's corrosion rate, 10 to 30vol% silver were added to the metal phase. The degradation behavior of the developed composite materials was studied by immersion in Ringer's and saline solutions for up to 1month. The mechanical properties, before and after immersion, were tested in compression and bending. All the compositions exhibited high mechanical strength, the strength in bending being several fold higher than that of polymer toughened β-TCP-30PLA nanocomposites prepared by the similar procedure of attrition milling and cold sintering, and of pure high-temperature sintered β-TCP. Partial substitution of iron with silver led to an increase in both strength and ductility. Furthermore, the galvanic action of silver particles dispersed in the iron phase significantly accelerated in vitro degradation of β-TCP-30(Fe-Ag) nanocomposites. After 1month immersion, the composites retained about 50% of their initial bending strength. In cell culture experiments, β-TCP-27Fe3Ag nanocomposites exhibited no signs of cytotoxicity towards human osteoblasts suggesting that they can be used as an implant material.

The Inhibition Effect of Potassium Iodide on the Corrosion of Pure Iron in Sulphuric Acid

The use of inorganic inhibitors as an alternative to organic compounds is based on the possibility of degradation of organic compounds with time and temperature. The inhibition effect of potassium iodide on the corrosion of pure iron in 0.5 M H2SO4has been studied by weight loss. It has been observed from the results that the inhibition efficiency (IE%) of KI increases from 82.17% to 97.51% with the increase in inhibitor concentration from 1·10−4to 2·10−3 M. The apparent activation energy (Ea) and the equilibrium constant of adsorption (Kads) were calculated. The adsorption of the inhibitor on the pure iron surface is in agreement with Langmuir adsorption isotherm.

Some hydrazone derivatives as corrosion inhibitors for iron in 3.5% H3PO4 solution

The inhibition of corrosion of pure iron in 3.5% H3PO4 by some hydrazone derivatives has been investigated by weight loss and galvanostatic polarization techniques. The inhibition efficiency was increased by increasing inhibitor concentration and decreased by rise in temperature. Polarization studied revealed that these compounds behave as mixed-type inhibitors. The inhibition action of hydrazone derivatives was performed via adsorption of these compounds on iron surface following Frumkin adsorption isotherm. The corrosion behavior of iron in 3.5% H3PO4 solution in the presence of hydrazone-halide mixtures was studied. Some thermodynamic parameters were calculated and discussed. The correlation between the inhibition efficiency and quantum chemical parameters wasinvestigated in order to elucidate the inhibition mechanism of the investigated compounds. Key words: Corrosion, iron, H3PO4, hydrazone derivatives, quantum chemical calculations.

Biocorrosion properties and blood and cell compatibility of pure iron as a biodegradable biomaterial

Biocorrosion properties and blood- and cell compatibility of pure iron were studied in comparison with 316L stainless steel and Mg-Mn-Zn magnesium alloy to reveal the possibility of pure iron as a biodegradable biomaterial. Both electrochemical and weight loss tests showed that pure iron showed a relatively high corrosion rate at the first several days and then decreased to a low level during the following immersion due to the formation of phosphates on the surface. However, the corrosion of pure iron did not cause significant increase in pH value to the solution. In comparison with 316L and Mg-Mn-Zn alloy, the pure iron exhibited biodegradable property in a moderate corrosion rate. Pure iron possessed similar dynamic blood clotting time, prothrombin time and plasma recalcification time to 316L and Mg-Mn-Zn alloy, but a lower hemolysis ratio and a significant lower number density of adhered platelets. MTT results revealed that the extract except the one with 25% 24 h extract actually displayed toxicity to cells and the toxicity increased with the increasing of the iron ion concentration and the incubation time. It was thought there should be an iron ion concentration threshold in the effect of iron ion on the cell toxicity.

Influence of H+ and Cl− ions on inhibitive performance of poly(aniline) for iron corrosion in acid

AbstractThe inhibition effect of poly(aniline) on pure iron corrosion in 1M HCl and with various H+ ions and Cl− ions concentrations was investigated by the polarization and electrochemical impedance spectroscopy methods. The results showed that poly(aniline) suppressed both cathodic and anodic processes of iron dissolution in 1M HCl by its adsorption on the iron surface according to Langmuir's adsorption isotherm. The inhibition efficiency of poly(aniline) was found to increase with the inhibitor concentrations. Further, it was observed that, there was no significant variation in corrosion potential (Ecorr) values in the presence of inhibitors suggesting that, this polymer behaved as mixed type inhibitor. Similar studies for the inhibitor at 500 ppm in various concentrations of H+ and Cl− ions, have shown that the inhibition efficiency decreases with decrease in concentrations of H+ ions and Cl− ions in aqueous solution. It reveals that, the adsorption of inhibitor on iron surface is by more cationic form of inhibitor and higher efficiency at higher H+ and Cl− ions is due to enhanced adsorption of cat ionic form of inhibitor molecules. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Inhibition of pure iron by new synthesized tripyrazole derivatives in HCl solution

Inhibitory effect of some new synthesized tripyrazole compounds on corrosion of pure iron in 1 M HCl solution has been studied using weight-loss measurements and various electrochemical techniques polarization and impedance spectroscopy methods. The inhibiting action is more pronounced with N, N, N-tris[(3,5-dimethyl-1H-pyrazol-1-yl)methyl] amine (P1), and its inhibition efficiency increases with its concentration and attains the maximum value of 94% at the 2.5 × 10 −4 M. The effect of temperature on the corrosion behaviour of iron was studied in the range from 298 to 353 K with and without P1 at 2.5 × 10 −4 M. We note a good agreement between gravimetric and electrochemical methods potentiodynamic polarization and impedance spectroscopy (EIS). Polarization measurements show also that the compound acts mixed inhibitor. The catholic curves indicate that the reduction of proton at the pure iron surface happens within a pure activating mechanism. EIS measurements show the increase of the transfer resistance with the inhibitor concentration. The presence of the N, N, N-tris[(3,5-dimethyl-1H-pyrazol-1-yl)methyl] amine increases the inhibition efficiency and not caused a drastic change in its adsorption mechanism. The adsorption of P1 on the surface of iron in 1 M HCl obeys a Langmuir isotherm adsorption.

Inhibitive action of bipyrazolic type organic compounds towards corrosion of pure iron in acidic media

Inhibitory effect of some new synthesized bipyrazole compounds, namely, N, N-bis[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]- N-(4-methylphenyl)amine (P1) and methyl-1-[((methylphenyl){[3-(methoxycarbonyl)-5-methyl-1H-pyrazol-1-yl]methyl}amino)methyl]-5-methyl-1H-pyrazole-3-carboxylate (P2) on corrosion of pure iron in 1 M HCl solution has been studied using chemical technique as weight loss and electrochemical techniques as potentiodynamic polarization, linear polarization and impedance. The inhibition efficiencies obtained from gravimetric, cathodic Tafel plots, linear polarization resistance and EIS methods are in good agreement. The results obtained reveal that these compounds are efficient inhibitors. The inhibition efficiency increases with the increase of inhibitor concentration to reach 93% for P1 at 2.5 × 10 −4 M. Potentiodynamic polarisation studies clearly reveal that P1 and P2 act as mixed-type inhibitors without change of the mechanism of hydrogen evolution. The temperature effect on the corrosion behaviour of iron in 1 M HCl without and with the inhibitors at 2.5 × 10 −4 M has been studied in the temperature range from 298 to 353 K. EIS measurements show that the increase of the transfer resistance with the inhibitor concentration. The inhibitors are adsorbed on the iron surface according to the Langmuir adsorption isotherm model. From the adsorption isotherm some thermodynamic data for the adsorption process (K and Δ G ads ° ) are calculated and discussed.

Influence of Cr content on the corrosion of Fe-Cr alloys: The synergistic effect of NaCl and water vapor

The corrosion behavior of pure Fe and Fe-Cr alloys with different Cr content in the presence of a solid NaCl deposit and water vapor at 600degreesC was studied. Results indicated that the corrosion of pure Fe was severe even in air at 600degreesC and the scale formed on the surface was compact and uniform. However, with a solid NaCl deposit on its surface, the corrosion of pure iron in air was suppressed to some extent, but the presence of water vapor in the atmosphere causes accelerated corrosion. Under the synergistic effect of NaCl and water vapor, the corrosion of pure iron is accelerated more significantly. In contrast with the known effect of Cr content on the oxidation of Fe-Cr alloys, an increasing Cr content in Fe-Cr alloys increases the corrosion rate of the alloys under the synergistic effect of solid NaCl and water vapor. A mechanism to explain the effect of water vapor and NaCl on the corrosion of pure iron and Fe-Cr alloy is proposed.

An Experimental Study of Iron Corrosion in Sulfuric Acid Solution Containing Inhibitors by Noise Measurement

The corrosion of pure iron was studied by electrochemical noise potential measurements in 0.5 mol/dm3 containing dibenzyl sulfoxide and plenyl thiourea, respectively, as the inhibitor. The corrosion current density was found to be inversely proportional to the mean square of the potential noise. The proportionality constant was determined with solution analysis and harmonic analysis.

Mechanism of inhibition of iron corrosion in HCl by acetylenic alcohols

Introduction The mechanism of the inhibition of the corrosion of iron in HCl by acetylenic alcohols, is investigated by weight change method, galvanostatic method and faradic impedance method. Propargyl alcohol offers greater protection than 3‐butyn‐2ol, 2‐methyl‐3‐butyn‐2‐ol and 2‐butyn 1,4 diol in hydrochloric acid solution of concentrations (1.0 to 8.0M). The corrosion of pure iron in hydrochloric acid solutions involves the participation of adsorbed FeOH intermediate and forms chlorhydroxy iron complex. The addition of ferrous ion is found to favour the three‐dimensional chelation with inhibitor molecule, leading to polymen film formation. With prolonged exposure the thickness of the polymer film increases.

金属-CO<sub>2</sub>/H<sub>2</sub>S-水系の高温電位-<i>p</i>H図と純鉄の腐食への適用

In the analysis of corrosion behaviors of metals in oil & gas well and chemical plants containing CO2 and/or H2S gas, detailed knowledge of a stable corrosion product and its solubility is essential. Thus, a computer program has been developed that can automatically construct the potential-pH diagram and calculate the solubility of corrosion product at elevated temperatures for Metal-CO2/H2S-H2O system. The partial pressure of CO2 or H2S gas in this program was used as the input parameter because that can be measured in laboratory tests and actual fields. The thermodynamic data of H2CO3 and H2S (aq) were used in the program, since chemical species such as H2CO3, HCO3- and CO32- are produced when CO2 or H2S gas dissolved are thermodynamically in the equilibrium state. Then, the corrosion of pure iron in CO2 environments was discussed based on the potential-pH diagram for Fe-CO2-H2O system and the solubility of FeCO3. The solubility decreased as the temperature increased, and the pure iron showed the maximum corrosion rate because the FeCO3 film was partially produced on metal surface around 100°C, and then the corrosion rate decreased above 150°C because of the protective FeCO3 film layer. Finally, the solubility of FeS in Fe-H2S-H2O system is very low compared with that of FeCO3, and the corrosion rate of the pure iron was also low at 60 and 100°C, but that increased above 150°C. In this case, the phase transition of FeS from α to β was an important factor.

Electrochemical reduction of carbon dioxide and the effect of the enzyme carbonic anhydrase 11 on iron corrosion

AbstractThe corrosion of pure iron in carbon dioxide saturated solutions at low temperatures has been investigated in this study. Both dc polarisation and ac impedance techniques were used in conjunction with a rotating disc electrode to investigate the reaction sequence leading to hydrogen evolution at 30°C. The results indicate that protons from the low pH solution, the bicarbonate ion and the undissociated carbonic acid molecule contribute to the reaction sequence leading to eventual hydrogen evolution. The corrosion mechanism involves both activation and diffusion processes. A rotating disc electrode in combination with ac techniques and the enzyme carbonic anhydrate II, EC 4.2.1.1, were used to characterise the diffusion effects. A chemical–electrochemical cathodic reaction mechanism is proposed.

Electrochemical evaluation of the effect of binder additives on iron corrosion

Recent research efforts have emphasized the archivability of metal particle media which utilizes ‘‘passivated’’ iron particles as the magnetic material. Two fundamental processes limit the archival lifetime of such media (1) corrosion of metal particles, and (2) degradation of polymer binder. This paper addresses the first process by quantifying the effect of pH and various binder additives (lubricant, dispersant, polymer degradation products, etc.) on the corrosion of pure iron in aqueous 0.05 M K2SO4. This study is unique in its use of electrochemical techniques to adequately quantify the corrosion process. Both ac [electrochemical impedance spectroscopy, (EIS)] and dc polarization techniques have been used. Experimental data showed that the addition of stearic acid (a lubricant) and lecithin (a dispersant) resulted in a decrease in the corrosion rate of iron in K2SO4. Five different carboxylic acids of various chain lengths were investigated since such compounds can be viewed as simple models for binder additives, or as polymer degradation products. Except for stearic acid, all of the carboxylic acids significantly accelerated iron dissolution at the corrosion potential. The corrosion rate increased as chain length or pH decreased and as acid concentration increased. The charge involved in passive film formation increased as the solution becomes more acidic, indicating that the passive film was less stable or more difficult to form. In the passive region the corrosion rate was lower than that of the base electrolyte for high concentrations of carboxylic acids.

Erosion and corrosion of pure iron under cavitating conditions

Pure iron has been eroded in various aqueous solutions at 50°C using a 20 kHz vibratory facility and the erosion kinetics determined, the corrosion component during erosion determined electrochemically, the size distribution of the erosion products determined and the eroded surface examined metallographically. Salt in the water increased the erosion rate 1.4 times and gave a smaller maximum size of eroded particle, and the erosion, corrosion and corrosion-induced erosion components of damage were estimated to be the fractions 0.71, 0.10 and 0.19, respectively. The effects of an inhibitor, pH, cathodic protection and amplitude of vibration on the erosion were also briefly examined. The results are presented and discussed in terms of the erosion/corrosion processes.

Study of the Inhibitory Action of Nitrogen-Containing Compounds

Abstract The effect of urotropine, homopiperazine, and n-decylamine on the corrosion of pure iron in deaerated and aerated 0.1 M Na2S04 solution, with a pH value 2, at 25 C, was investigated by polarization techniques and measurements of the double layer capacitance using the single pulse method. It was found that urotropine and homopiperazine were adsorbed on the pure Fe surface according to a Frumkin isotherm. The n-decylamine and homopiperazine were chemisorbed, while the urotropine produce a physical adsorption.

Corrosion of pure iron in acetic anhydride

Corrosion of pure iron in acetic anhydride

硫酸中の鉄腐食に対する n-アルキルトリメチルアンモニウム硫酸塩の効果

硫酸中の鉄腐食に対する n-アルキルトリメチルアンモニウム硫酸塩の効果

Contrasting Behaviour of Mild Steel and Pure Iron towards Pickling Inhibitors

Abstract Long-chain n-alkyl-trimethyl- and -triethyl-ammonium sulphates give good inhibition of the corrosion of mild steel in 0·5 M H2S04, but little or no inhibition with pure iron. This is probably because mild steel is negatively charged in O·5 M H2SO4 whereas pure iron ispositive.Although the sulphates of n-alkyl-trimethy- and -triethyl-ammonium compounds give little inhibition of the corrosion of pure iron in 0·5 M H2SO4, the corresponding bromides give good inhibition. The experimental results suggest that there is a mutual stimulation of adsorption between the bromide and the quaternary ammonium ions.Polarisation measurements show that the quaternary ammonium bromides give a higher proportion of cathodic inhibition with iron than with steel, presumably because of the more restricted cathodic reaction of iron.There are considerable differences between mild steel and pure iron in the effects of the quaternary ammonium bromides on the anodic and cathodic Tafel slopes. These results are discussed in t...

The influence of oxide adherence on the hot-salt corrosion of mild steels

The corrosion of pure iron and some mild steels by sodium chloride has been investigated in the temperature range 600 to 900° using hot-stage microscopy, a vibration technique, and quantitatively by means of a vapor exposure test. It has been found that for corrosive attack to occur it is necessary for the sodium chloride to have access to the metal surface, and that such access may be prevented by the presence of an adherent, impervious, scale layer at the metal surface. Such a layer was found to be present on an EN2 steel examined but was not formed on any of the other materials tested. The EN2 steel contained 0.2 pct Ni, and 0.21 pct Si, and both have been shown to become concentrated in the scale at the scale-metal interface. This produced an inner adherent scale which was resistant to sodium chloride penetration and which gave the material an appreciably enhanced corrosion resistance.