<i style="">Salvia officinalis</i> L. honey as corrosion inhibitor for CuNiFe alloy in sodium chloride solution

96-102Salvia officinalis L. honey has been tested as inhibitor for the corrosion of CuNiFe alloy in 0.5 M NaCl solution by electrochemical measurements. The honey solutions are prepared in different concentrations, such as 400, 600, 800, 1000 and 1200 ppm. Polarization curves show that the honey acts as mixed corrosion inhibitor, and the inhibition efficiency increases with an increase in honey concentration. The maximum corrosion inhibition efficiency of approximately 70 % is achieved with the highest inhibitor concentration (1200 ppm of honey). Changes in impedance parameters are indicative of adsorption of honey compounds on the metal surface. The adsorption of natural honey on the CuNiFe alloy follows the Langmuir adsorption isotherm

Corrosion inhibition of Al-Mg alloy by gentisic acid

89-94Gentisic acid was studied for possible use as an Al-2.5Mg alloy corrosion inhibitor in a 0.5 mol dm-3 NaCl solution. Investigations were performed on a rotating disc electrode in a quiescent solution at different electrode rotation rates and electrolyte temperatures. The results indicate that, the addition of gentisic acid inhibits corrosion of Al-2.5Mg alloy, and the inhibition efficiency increases with increasing inhibitor concentration but decreases with increasing electrode rotation rate and electrolyte temperature. The investigated compound acts as a cathodic-type inhibitor and the inhibition is ascribed to the adsorption of the inhibitor onto the electrode surface. The adsorptive behaviour of gentisic acid follows the Freundlich adsorption isotherm

Effect of Nb alloying additions on the characteristics of anodic oxide films on zirconium and their stability in NaOH solution

The characteristics of oxide films on Zr and Zr- Nb alloys (with Nb content of 2.5, 5, and 10 at.%) galvanostatically formed (at a current density of 100 μA cm−2) in 0.5 M H2SO4 solution were investigated by means of electrochemical impedance spectroscopy. Electrochemical impedance spectroscopy spectra were interpreted in terms of an "equivalent circuit" with the circuit elements representing the electrochemical properties of a single layer oxide. The resistance of the oxide films was found to increase with increased Nb content in the alloy while the capacitance showed an opposite trend. The stability of the anodic oxide films grown in the sulfuric acid solution on Zr and Zr-Nb alloys was investigated by simultaneously measuring the electrode capacitance and resistance at a working frequency of 1 kHz as a function of exposure time to naturally aerated 3 M NaOH solution. Analyses of the electrode capacitance and resistance values indicated a decrease in chemical dissolution rate of the oxide films with the increase of Nb content in the alloy

Influence of Zn and Mg Alloying on the Corrosion Resistance Properties of Al Coating Applied by Arc Thermal Spray Process in Simulated Weather Solution

In this study, Al–Zn and Al–Mg coatings were deposited on steel substrates by an arc thermal spray process. X-ray diffraction and scanning electr on microscopy were used to characterize the deposited coatings and corrosion products. Open circuit potential (OCP), electrochemical impedance spectroscopy, and potentiodynamic studies were used to assess the corrosion characteristics of these coatings after exposure according to the Society of Automotive Engineers (SAE) J2334 solution of varying durations. This solution simulates an industrial environment and contains chloride and carbonate ions that induce corrosion of the deposited coatings. However, the Al–Mg alloy coating maintained an OCP of approximately - 0.911 V versus Ag/AgCl in the SAE J2334 solution even after 792 h of exposure. This indicates that it protects the steel sacrificially, whereas the Al–Zn coating provides only barrier-type protection through the deposition of corrosion products. The Al–Mg coating acts as a self-healing coating and provides protection by forming Mg 6 Al 2 (OH) 16 CO 3 (Al–Mg layered double hydroxides). Mg 6 Al 2 (OH) 16 CO 3 has interlocking characteristics with a morphology of plate-like nanostructures and an ion-exchange ability that can improve the corrosion resistance properties of the coating. The presence of Zn in the corrosion products of the Al–Zn coating allows dissolution, but, at the same time, Zn 5 (OH) 6 (CO 3 ) 2 and Zn 6 Al 2 (OH) 16 CO 3 are formed and act to reduce the corrosion rate