Corrosion Activity of Carbon Steel B450C and Low Chromium Ferritic Stainless Steel 430 in Chloride-Containing Cement Extract Solution

The carbon steel B450C and low chromium SS 430 ferritic samples were exposed for 30 days to chloride-containing (5 g L−1 NaCL) cement extract solution. The initial pH ≈ 13.88 decreased to pH ≈ 9.6, associated mainly with the consumption of OH− ions and the formation of γ-FeOOH, α-FeOOH, Fe3O4 and Cr(OH)3, as suggested by XRD and XPS analysis, in the presence of CaCO3 and NaCl crystals. The deep corrosion damages on B450C were observed around particles of Cu and S as local cathodes, while the first pitting events on the SS 430 surface appeared after 30 days of exposure. The change in the activity of each type of steel was provided by the potentiodynamic polarization curves (PDP). Two equivalent electrical circuits (EC) were proposed for quantitative analysis of EIS (Nyquist and Bode diagrams). The calculated polarization resistance (Rp), as an indicator of the stability of passive films, indicated that SS 430 presented relatively constant values, being two-three orders of magnitude higher than those of the carbon steel B450C. The calculated thickness (d) of the SS 430 passive layers was ≈0.5 nm and, in contrast, that of the B450C passive layers tends to disappear after 30 days.

STUDY OF ELECTRODEPOSITION OF NICKEL FROM ALKALINE GLYCINE ELECTROLYTES

The essay is about studies of the electrochemical reduction of nickel ions from a glycine electrolyte by the method of recording cyclic and linear potentiodynamic polarization curves. The effect of the concentration of the main components, potential sweep and temperature on the electrodeposition process of nickel has been studied. It has been found that at the beginning of the process the electrodeposition of the nickel ions from glycine electrolyte is controlled by electrochemical polarization, which turns into concentration polarization

Influence of Nitrogen Content on the Corrosion Behavior of Powder Metallurgy Nickel-Free Austenitic Stainless Steel

Herein, powder metallurgy gas-solid nitriding was used to prepare a high-nitrogen Ni-free austenitic stainless steel with more than 1.0 wt.% N. Study of the microstructures and corrosion resistances of the as-prepared samples revealed that the corrosion weight loss, size, number of corrosion pits, and corrosion depth decreased as the N content increased from 1.19 to 1.37 wt.%. The self-corrosion current densities of the alloys were determined from their potentiodynamic polarization curves. The changes in the capacitive arc radius as demonstrated by the Nyquist curves were consistent with the conclusions of the immersion corrosion analysis; that is, a high N content leads to a high corrosion resistance.

Reversible Superwetting Transition Between Superhydrophilicity and Superhydrophobicity on a Copper Sheet, and Its Corrosion Performance

Dense copper oxide nanoribbons arrays are prepared on a copper sheet by using a low-temperature hydrothermal method. The wettability of the surface modified by stearic acid is superhydrophobic, and the water contact angle is 153.6°. It is demonstrated that the reversible transition from superhydrophilicity to superhydrophobicity is successfully achieved by heat treatment and re-modification, and the whole process can be accomplished in 170 s. Potentiodynamic polarization curves and Nyquist curves show that these superhydrophobic surfaces have good corrosion resistance and superior durability.

Analysis of experience in the use of corrosion-resistant tubing in gas wells and research the efficient of corrosion inhibitors

Purpose. Analysis of the efficient of corrosion inhibitors in the natural gas extraction on Lutsenkivske gas condensate deposit wells has been carried out. Methodology. Electrochemical measurements were obtained in 3% NaCl. All potentials were measured versus SCE. Potentiodynamic polarization curves were obtained at the scan rate of 0,2 mV/s. Findings. It has been established that inhibitors of SE-231-K and ACL-060 brands are effective for protection of corrosion-resistant pump-compressor pipes against corrosion in the aggressive environment on Lutsenkivske gas condensate deposit wells. Originality. For the first time, the analysis of the effectiveness of corrosion inhibitors in the form of sticks in the packer wells of the Lutsenkivske gas condensate deposit wells. Practical value. The results of the work will be used in the corrosion protection of packer wells of the Lutsenkivske gas condensate deposit wells. Keywords: pump and compressor pipes, gas wells, corrosion, inhibitors, corrosion protection

Increasing Corrosion Resistance of Pressure Vessels at the Hydrostatic Pressure Testing by Using Inhibitors

Studies of the corrosion initiation at the pressure hydraulic test of pressure vessels during their filling, maintaining and draining are presented. It has been established that the most suitable method involves the use of corrosion inhibitors, which directly decrease the corrosion rate even in small or very small quantities. It was studied the influence of some corrosion inhibitors at different concentrations on some steel materials commonly used at pressure vessels manufacturing. The study involved the inhibitors testing both in laboratory and in factory conditions. Testing in laboratory conditions involved the analysis of the following inhibitors: urea, thiourea, triethanolamine, FINEAMIN 88 and FINEAMIN 06. The results were compared with those of the Adirol inhibitor, the currently used inhibitor. It was investigated the corrosion of the following stainless steels and unalloyed steels: A 240 grade 304, A 240 grade 316, A 516 grade 70, A 516 grade 60, P260-GH, P265, P275, P295-GH, P295, and P355. By recording the potentiodynamic polarization curves, the corrosion parameters (corrosion potential, corrosion current density, polarization resistance, corrosion rate, charge transfer coefficients for anodic and cathodic processes, inhibitors acting coefficients, and inhibition efficiencies) have been evaluated. The following corrosion inhibitor solutions were selected for testing under the factory specific conditions: Instal Protect SP at concentrations of 5%, 7.5% and 10%, ELG INCOR SP at 10% concentration, FINEAMIN 06 at 10/00 concentration and a mixture of 40mL FINEAMIN 06 + 40 mL FINEAMIN 88 SCAV25 in 40 L water. The analysed steels were A 106 grade B and A 283 grade C. Tests in laboratory conditions revealed a different behaviour of the inhibitors, depending on the analysed concentration and steel grade. The inhibitors proven as appropriate following the tests in the factory conditions were ELG INCOR SP used in industrial water (tap water), whereas the mixture of FINEAMIN 06 + FINEAMIN 88 SCAV25 had efficiency only in demineralised water.

Corrosion and Micromorphological Analysis of Temporary Stainless Steel and Titanium Alloy Anchorage Devices

The aim of this study was to compare the surface micromorphology and corrosion resistance of diferent temporary anchoragedevices (TADs) composed of titanium alloy (SIN®) and stainless steel (DAT Steel® and Bio Ray®). Ten samples of eachTAD were submitted to qualitative analyses using energy-dispersive and scanning electronic microscopy before and afterimmersion in artifcial saliva (1500 ppm of fuoride) for 30 days. The chemical analysis was done by X-ray fuorescence,and the corrosion tests were performed by electrochemical means (open circuit potential—OCP, potentiostat, and electrochemical impedance spectroscopy—EIS, using anodic potentiodynamic polarization curves). Passive flm resistance (PFR)and corrosion current were established. The corrosion rate was determined by the mass loss test. Greater smoothness andfewer machining defects were observed for the stainless steel TAD before artifcial saliva immersion. Comparatively, highercorrosion resistance was found for titanium alloy TAD after immersion in saliva. There was no release of ions into the TADwhen immersed in artifcial saliva. ANOVA and Tukey tests showed that OCP (V) was signifcantly lower for the titaniumalloy TAD (p=0.030) than the stainless steel brands. Epite (V) and Epite−OCP (V) were signifcantly higher for the titaniumalloy TAD (p=0.0009 and p=0.0005, respectively). Stainless steel TADs presented lower roughness surface than titaniumalloy TAD, although the latter presented higher corrosion resistance than the former

CORROSION BEHAVIOR OF Ti–Al–N COATING MODIFIED ON CARBON STEEL PREPARED AT DIFFERENT TEMPERATURES

In this paper, pulsed arc ion plating was applied for preparing Ti–Al–N coatings. The effects of different process parameters on the structure and corrosion resistance properties of Ti–Al–N coating were studied by changing the temperature. The microstructures, morphology features and the corrosion resistance of the different temperatures of Ti–Al–N coating were investigated to simulate the corrosion conditions of seawater. All the samples (prepared at [Formula: see text]C, [Formula: see text]C, [Formula: see text]C and [Formula: see text] were measured in 3.5[Formula: see text]wt.% NaCl solution at [Formula: see text]C and characterized by potentiodynamic polarization curves, scanning electron microscopy (SEM) combined with analyzed by X-ray diffraction (XRD). The corrosion resistance of carbon steel was improved by the coating modification. The results showed that the sample prepared at [Formula: see text]C possesses excellent corrosion resistance where corrosion current density can only reach to 11.176[Formula: see text][Formula: see text]A/cm2, Meanwhile, SEM images also revealed that the microstructure of the sample is much smoother and nearly no defects can be observed.

Effect of Biological Solution and pH on Corrosion Resistance of 304L SS for Dental Brackets

This study is undertaken to evaluate the accuracy of corrosion resistance of commercially available 304L stainless steel in biological solutions with different composition and pH. Electrochemical methods such as: open circuit potential (OCP), potentiodynamic polarization curves (PD), linear polarization resistance (Rp) and cyclic polarization (CV) were used for corrosion investigations. The results show different behavior during corrosion tests in the solutions with different pH, different content of chlorides and different oxidizing character. Highest instability is revealed for 304L stainless steel in Hank`s solution due to the presence of chloride aggressive ions.