Utjecaj korozijskih inhibitora na krivulje ohlađivanja sredstva za kaljenje na bazi sojinog ulja

The relative inhibitory effect of a series of common yellow-metal (brass) corrosion inhibitors was studied potentiodynamically in a saline solution. The results of this study showed that all of the corrosion inhibitors examined could potentially exhibit substantial cooling time and rate reduction. The magnitude of this effect was corrosion inhibitor specific. Corrosion and cooling curve supporting data are provided.Relativni inhibitorski efekt niza korozijskih inhibitora obojenih metala (bronca) istraživani su potencijo-dinamički u solnim kupkama. Rezultati istraživanja pokazali su da svi ispitani korozijski inhibitori mogu utjecati na vrijeme ohlađivanja i smanjenje brzine ohlađivanja. Veličina tih efekata ovisila je o pojedinom korozijskom inhibitoru. Prikazani su podaci za koroziju kao i utjecaji na krivulje ohlađivanja

Effect of partial substitution of nickel by tin, aluminum, manganese and palladium on the properties of LaNi5-type metal hydride alloys

This work reports studies on the electrochemical behavior of AB5-type hydrogen storage alloys, formed by LaNi(5-x)Zx, where Z is a metallic element partially replacing Ni, which included Sn, Al, Mn, and Pd. In the case of Mn, some AB6-type structures were also considered. Substitution of a small fraction of Ni by Al, Sn, and Mn (x <FONT FACE=Symbol>@</FONT> 0.3) leads to an increase of the hydrogen storage capability (HSC), while for Pd there is a decrease of this property. Generally all alloys presenting larger initial HSC exhibit lower stability. A decrease of the hydrogen equilibrium pressure as a function of Mn content is observed for the AB5 alloys and this is related to an increase of the crystalline unit cell volume. Electrochemical impedance measurements show a significant increase of the hydration/dehydration reaction kinetics due to a raise on the active area as a function of the charge/discharge cycle number. It is also seen that the alloys presenting larger HSC are those showing smaller activation energies for the hydrogen oxidation reaction

Effect of partial substitution of nickel by tin, aluminum, manganese and palladium on the properties of LaNi5-type metal hydride alloys

This work reports studies on the electrochemical behavior of AB5-type hydrogen storage alloys, formed by LaNi(5-x)Zx, where Z is a metallic element partially replacing Ni, which included Sn, Al, Mn, and Pd. In the case of Mn, some AB6-type structures were also considered. Substitution of a small fraction of Ni by Al, Sn, and Mn (x <FONT FACE=Symbol>@</FONT> 0.3) leads to an increase of the hydrogen storage capability (HSC), while for Pd there is a decrease of this property. Generally all alloys presenting larger initial HSC exhibit lower stability. A decrease of the hydrogen equilibrium pressure as a function of Mn content is observed for the AB5 alloys and this is related to an increase of the crystalline unit cell volume. Electrochemical impedance measurements show a significant increase of the hydration/dehydration reaction kinetics due to a raise on the active area as a function of the charge/discharge cycle number. It is also seen that the alloys presenting larger HSC are those showing smaller activation energies for the hydrogen oxidation reaction

Influence of chloride ion concentration and temperature on the electrochemical properties of passive films formed on a superduplex stainless steel

Polarization measurements were conducted to monitor the corrosion behavior of superduplex stainless steel ASTM A995M-Gr.SA/EN 10283-Mat#1.4469(GX2CrNiMo26-7-4) when exposed to a) an electrolyte containing 22,700 parts per million (ppm) of chloride ions at seven different temperatures and b) an electrolyte at 25 GC and different chloride ion concentrations (5800, 22,700, 58,000 and 80,000 ppm of Cl(-)). The polarization curves indicate that the passive films formed are only slightly affected by NaCl concentration, but the pitting potential decreases drastically increasing the temperature, in particular >60 degrees C. The image analysis of the microstructure after potentiodynamic polarization showed that the pitting number and size vary in function of the temperature of the tested medium. Nyquist diagrams were determined by electrochemical impedance spectroscopy to characterize the resistance of the passive layer. According to Nyquist plots, the arc polarization resistance decreases increasing the temperature due to a catalytic degradation of the oxide passive films. (C) 2009 Elsevier Inc. All rights reserved.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP