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Various materials are used in medicine and the main requirement is their biocompatibility, including corrosion resistance. In addition to destroying materials, the products released during corrosion can cause adverse reactions in the human body. Corrosion testing of any material proposed for biomaterials should therefore be conducted in a model or controlled environment similar to that of the human body. In this work, the results obtained in the study of high nitrogen stainless steel (HNS) as a material for the fabrication of implants are presented and compared with the results for classical Cr-Ni stainless steel, in analogous environments and conditions. The tests were carried out in Ringer’s and Hartmann’s solutions, at specified concentrations, temperatures and pH values. A three-electrode glass cell was used under open air conditions. The following electrochemical methods were used: open circuit potential (OCP) – time measurement, cyclic potentiodynamic and potentiostatic polarizations. By means of light and scanning electron microscopy, surface changes were determined after exposing the steel specimens to the experimental media. The surface of the samples was also examined by EDX analysis to determine the nature of the corrosion products formed. From the results obtained, it was found that HNS-steel has higher resistance than Cr-Ni-steel in the model solutions studied.

Various materials are used in medicine and the main requirement is their biocompatibility, including corrosion resistance. In addition to destroying materials, the products released during corrosion can cause adverse reactions in the human body. Corrosion testing of any material proposed for biomaterials should therefore be conducted in a model or controlled environment similar to that of the human body. In this work, the results obtained in the study of high nitrogen stainless steel (HNS) as a material for the fabrication of implants are presented and compared with the results for classical Cr-Ni stainless steel, in analogous environments and conditions. The tests were carried out in Ringer's and Hartmann's solutions, at specified concentrations, temperatures and pH values. A three-electrode glass cell was used under open air conditions. The following electrochemical methods were used: open circuit potential (OCP) time measurement, cyclic potentiodynamic and potentiostatic polarizations. By means of light and scanning electron microscopy, surface changes were determined after exposing the steel specimens to the experimental media. The surface of the samples was also examined by EDX analysis to determine the nature of the corrosion products formed. From the results obtained, it was found that HNS-steel has higher resistance than Cr-Ni-steel in the model solutions studied. [ABSTRACT FROM AUTHOR]

A novel modified polyaspartic acid (PASP/CD) was synthesized from thiocarbazide and polysuccinim-ide. Secondly, the structure of PASP/CD was characterized by infrared spectroscopy (FT1R) and hydrogen nuclear magnetic resonance spectroscopy (NMR). Finally, the corrosion inhibition behavior of PASP/CD on carbon steel was studied by gravimetry, electrochemical method, atomic force microscope (AFM), contact angle and scanning electron microscope and energy spectrum (SEM/EDS) in 0.5 mol/L hydrochloric acid solution. The results show that when PASP/CD is added into hydrochloric acid solution as a mixed corrosion inhibitor, the charge transfer resistance of the system increases significantly. When the concentration of PASP/CD is 80 mg/L, the corrosion inhibition efficiency reaches 91.48%, which is much higher than PASP. Compared with PASP, the corrosion inhibition performance of PASP/CD is less affected by temperature. The figures and roughness data of AFM show that PASP/CD has good corrosion inhibition performance. It is found that the inhibition effect of PASP/CD is due to the physical and chemical adsorption of new functional groups on the steel surface. This work provides technical support for broadening the comprehensive properties of green water treatment agent polyaspartic acid. [ABSTRACT FROM AUTHOR]

An applied electrochemical method in the form of a chronocoulometry technique is proposed for measuring Fick's diffusion constant of a thin protective coating layer over the conductive base materials. Using this method, the capacitance is monitored for a capacitor formed using the base material, an electrolyte such as aqueous NaCl, and an insulating coating layer in between. The capacitance increases when the distance between the base material and the electrolyte decreases in the diffusion of the electrolyte through the insulating coating layer. Therefore, the change in the capacitance provides a diffusion rate related to Fick's diffusion constant. Conventional gravimetric methods require a long measurement time to reach saturation, and thin coating layers of minimal weight increment through water diffusion were demonstrated to be inadequate for the methods. However, the new electrochemical method is appropriate for thin coating layers and requires a limited duration after the onset of diffusion. Experimental for 1-mm thick PA6 films provided Fick's diffusion constants of safer side with the new method of 15h by reflecting the heterogeneous properties of the surface, while the conventional gravimetric method in 360h provided smaller or danger-side values. [ABSTRACT FROM AUTHOR]

The investigation of the effect of Grass Jelly (Platostoma palustre) extract to the corrosion behavior of carbon steel had been carried out using electrochemical methods such potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Those experiments define corrosion rate, efficiency of inhibition and adsorptions isotherm values in 0.1 M hydrochloric acid solution. That extract was added gradually in acid solution up to 1,000 ppm. It found that the maximum of inhibition efficiency could reach 93% at 250 ppm concentration of extract. Typically, the efficiency of inhibition increased with increasing concentration of extract which tends to stable in the concentration range between 300 ppm and 1,000 ppm. The type of the extract is mixed inhibitor where it can inhibit the corrosion process in both anodic and cathodic sides. It presumed that the mechanism of adsorption on surface of metal corresponds to Langmuir adsorption isotherm. [ABSTRACT FROM AUTHOR]

The biofuel plays an important role as a renewable source of energy in diminishing globally warming and safeguard energy security by reducing the world's dependence on fossil energy sources. The aim of this work is to investigate the effect of methanol-gasoline blends on fueling infrastructure materials namely mild steel and stainless-steel. The degradation of metals and fuels takes place when the metals contact the fuel. The corrosion behavior is studied by mass loss and potentiodynamic polarization methods at a room temperature and 40°C within different time periods. The immersion tests indicate that the mild steel has good imperviousness when compared to that of stainless steel under static conditions. The steel coupons exposed to the fuel blends exhibit a decrease of the polarization resistance values with the increase of the methanol concentration. The comparison of the corrosion rates of the metals studied leads to the conclusion that mild steel is a suitable material for the construction of storage tanks, whereas stainless-steel can be used for transportation pipelines because of the longer life provided. [ABSTRACT FROM AUTHOR]

• Corrosion rate of Ni-based alloys in chloride melts was electrochemically evaluated. • Surface composition of alloys was analyzed by GD-OES. • Coordination structure of O2− ions in the melts was revealed by Raman spectroscopy. • The melt composition determines the stability of the corrosion products in the melt. For the long-term operation of integral molten salt fast reactor safety, it is necessary to select structural materials with high corrosion resistance such as Ni-based alloys in high-temperature chlorides of specific composition. In this study, the corrosion behavior of Inconel 600, Inconel X750, Hastelloy C-276, and Incoloy 800, which are the candidates for the structural materials in NaCl-KCl-MgCl 2 melt at 723 K and NaCl-CaCl 2 melt with CeCl 3 or LaCl 3 at 873 K were investigated by electrochemical and spectroscopic analyses toward designing materials used in the integral molten salt fast reactor. The corrosion rates were estimated based on the elemental analysis of alloy surfaces by glow-discharge optical emission spectroscopy and the corrosion current density by linear polarization technique. It was found that the trend of corrosion rate for each alloy changed significantly depending on the composition of the chloride melts. The electrochemical behavior obtained from the linear polarization measurement and the impedance spectroscopy indicated that the cathodic reaction during the corrosion process was different among each melt. To discuss the effect of molten salt composition on corrosion behavior, the melt structure was investigated by high-temperature Raman spectroscopy and density functional theory calculation. The results indicated that the coordination structure of oxide ions, which are corrosion products formed in the cathodic reaction, changed depending on the composition of the chloride melts. The reported data show that it is important to control the corrosion process by clarifying the structure of each melt in order to select a highly compatible system of molten salt and structural material. [ABSTRACT FROM AUTHOR]

The aim of the study was to investigate various rare earth salts as corrosion inhibitors of aluminium alloy 7075-T6. Rare earth salts, CeCl3, LaCl3, Ce(NO3)3and La(NO3)3, were studied, first as individual inhibitors in the concentration range between 0.001 and 0.05 M. Second, the inhibitory effect of mixtures of chloride or nitrate salts was studied at an overall inhibitor concentration of 0.01 M. The corrosion properties of AA7075-T6 in the absence and presence of individual and mixed rare earth salts were investigated using electrochemical potentiodynamic technique in 0.1 M NaCl. The topography, morphology and composition of the inhibited surfaces were recorded. The highest inhibitory effectiveness was exhibited by CeCl3, followed by mixtures of CeCl3and LaCl3. During immersion for 12 h the corrosion protection remained high. Nitrate rare earth salts showed less protection, both as individual or as mixed inhibitors. Deposits containing both cerium and lanthanum were formed primarily on Cu-based intermetallics. [ABSTRACT FROM AUTHOR]

The corrosion of steel tubes in sea water was controlled by cathodic protection. The impressed current technique was used. The rate of reaction was evaluated as a function of the temperature, pH and solution velocity. In this technique, the polarization method was used to determine the protection potential and current. The rate of zinc consumption, the protection potential, and the protection current are highly dependent on the variables of the study. The boundary element technique was suitable for modelling corrosion problems. The average percentage of error among the experimental and theoretical data was 1.27%. [ABSTRACT FROM AUTHOR]

In the field of hard cutting, researches on white layer have become more extensive and in-depth in recent years, because white layer has an important influence on the performances and life of components. Nevertheless, properties of white layer, especially its corrosion properties, have not been well understood or clearly defined. In this study, specimens with different subsurface microstructures (no obvious change, dark layer, and white layer) were produced in the process of tool wear to analyze their electrochemical properties using electrochemical methods. It was found that electrochemical properties were distinct between specimens with and without white layer. A specimen with white layer had obviously lower electrochemical impedance and more anodic steady-state open-circuit potential than that without white layer in 3.5 wt.% NaCl solution. That is to say, specimens with white layer were prone to corrosion in this solution. The results also manifest that electrochemical method can be a reliable, convenient, and nearly nondestructive method to detect white layer. [ABSTRACT FROM AUTHOR]

Abstract: The effectiveness of sulfonated Kraft lignin (LS) as corrosion inhibition material of steel bar grade 60 (ASTM A615) in water distribution systems was studied using potentiodynamic polarization and electrochemical impedance methods. LS were evaluated primarily for iron-based materials in water distribution systems. The experiments were performed on different solutions which simulated internal conditions of water distribution pipelines without or with different corrosion inhibitors. Potentiodynamic polarization and electrochemical impedance were used to evaluate the iron-based material''s corrosion resistance under these conditions, and linear polarization resistance (LPR) tests were used to compare the efficiency of the corrosion inhibitor. The potentiodynamic polarization studies showed a reduction in the pitting potential to more noble potential for protected corrosion cell. Consistently, the electrochemical impedance spectroscopy tests showed an increase in the corrosion resistance for iron-based material treated by sulfonated lignin. Based on the potentiodynamic polarization studies and electrochemical impedance spectroscopy tests, the LS optimal dosage was found to be 0.3–0.4mg/L. The conducted polarization resistance tests showed a decrease in corrosion rates of LS treated iron. This study showed that LS provided increased protection for iron-based materials in water distribution pipelines by inhibiting corrosion. [Copyright &y& Elsevier]

In this study, a new solution based on hydrochloric acid (HCl) and sodium thiosulfate (Na2S2O3 has been developed for detecting and measuring degree of sensitization (DOS) using the double-loop electrochemical potentiodynamic reactivation (DL-EPR) method. Two types of stainless steels including Type 304 (UNS $30400) and 28Cr-33Ni-39Fe were sensitized at 650 °C for 10, 60, and 300 min. The results revealed that the new solution can detect sensitization in stainless steels suitably with higher resolution than previously reported solutions. The optimum acid concentrations were 0.1 M and 0.4 M HCl for Type 304 stainless steel and 28Cr-33Ni-39Fe, respectively. For Type 304 stainless steel, the depassivator concentration was 0.002 M Na2S2O3, while it was 0.001 M for 28Cr-33Ni-39Fe. [ABSTRACT FROM AUTHOR]

Abstract: In order to investigate the influence of the confinement on the corrosion behaviour of metallic materials, an innovative thin layer electrochemical cell was developed. The cell includes a device which allows a continuous gas supply within the electrolyte film covering the metallic specimen under study. A procedure based on high frequency impedance measurements is also proposed to control and precisely adjust the setting of the electrolyte film geometry. The experimental set-up was validated by performing measurements of the stationary limiting cathodic current on a steel disk immersed in a K2SO4 aerated solution for various electrolyte layer thicknesses. The results obtained demonstrate the reliability of the experimental method. [Copyright &y& Elsevier]

Chemical decontamination is accepted as one of the effective methods for decreasing radioactivity from radioactive materials existing in the systems of the nuclear power plants. In chemical decontamination processes, metal oxides dissolve in chelating agents such as oxalic acid and EDTA (Ethylenediaminetetraacetic acid) in the dissolution step for the chemical decontamination process. It is important to investigate corrosion behaviors with respect to decontaminating agents in the development of decontamination process. In this study, the potentiodynamic method was considered among electrochemical methods in order to investigate corrosion behaviors of stainless steels (SS 316, SS 304) and a nickel alloy (Inconel 600). The corrosion behaviors observed in the potentiodynamic results agreed with those of corrosion behaviors observed in the weight loss method, showing that the electrochemical study is a very useful method for estimating corrosion behavior. [ABSTRACT FROM AUTHOR]

• Effect of DNA inhibitor on chloride-induced steel corrosion under SO 4 2− was studied. • The corrosion inhibition mechanisms were dissected by linear polarization and EIS. • XPS was performed to examine surface membrane on steel electrode. In this paper, a mixture of primers with a length of 20–80 bases were dissolved in a nucleic acid buffer as a deoxyribonucleic acid (DNA) corrosion inhibitor. The effect of coexisting anion SO 4 2− on the corrosion inhibition of DNA on the chloride-induced corrosion of reinforced steel in simulated concrete pore solution was studied by linear polarization and electrochemical impedance spectroscopy (EIS). The structure of the surface membrane of steel electrode after different treatments was analyzed using X-ray photoelectron spectroscopy (XPS). The results showed that the presence of SO 4 2− in the Cl− abundant environment adversely reduced the corrosion inhibitor efficiency of the DNA corrosion inhibitor. Interestingly, with the increase of NaCl concentration, the effect of SO 4 2− on the corrosion resistance of DNA corrosion inhibitor and commercial corrosion inhibitor was smaller and less. More importantly, the efficiency of the adopted DNA corrosion inhibitor was higher than that of the typical commercial corrosion inhibitor (sodium phosphate) under the same condition. Findings from this study may provide new insights into the use of environmentally-friendly corrosion inhibitor in reinforced concrete structures and their performance in the presence of sulfate ions. [ABSTRACT FROM AUTHOR]