Passivity of ?-brass (Cu?Zn/67?33) and its breakdown in neutral and alkaline solutions containing halide ions

Abstract

The passivation behaviour of e-brass (Cu : Zn = 67: 33) in alkaline solutions was studied using cyclic voltammetry and potentiostatic current transient measurements. The recorded cyclic voltammograms exhibited the main features usually observed for pure copper and zinc, and one additional anodic peak on the reverse potential scan. The height, sharpness and location of the different peaks depended greatly on the alkali concentration and the scan rate. The results show that the formation of Cu20 and Cu(OH)2 films proceed under ohmic resistance control following a dissolution-precipitation mechanism. The effect of F-, C1-and Br-ions on the passivity was also studied. The pitting potential was found to decrease with logarithm of halide ion concentration. The current transients in the absence and presence of halide ions were analysed. In the absence of pitting the current, after a few seconds, was found to increase linearly with the reciprocal of the square root of time while in the presence of pitting it was found to fit the Engell-Stolica equation.

A model for prolonged dezincification ofα-brasses in 3% sodium chloride buffer solutions at different pH values

“…Although the corrosion rates for the two alloys in the presence of chloride ions were close, they were significantly different in the absence of chloride ions (alloy I b alloy III). The presence of chloride ions shifted E corr to more negative values at all pH as reported before [21,22]. Such shifts were accompanied by an increase in the corrosion rate (relative to the absence of chloride ions) for alloy III and a decrease for alloy I.…”

Theoretical and experimental investigations on corrosion control of 65Cu–35Zn brass in nitric acid by two thiophenol derivatives

“…Brass is broadly used as tubing material for condensers and heat exchangers in various cooling water systems [2][3][4][5]. This family of copper alloys is susceptible to a corrosion process known as dezincification and it susceptibly increases as zinc content increases [6]. Among the corrosive media, the nitric acid is recognized as a strong oxidizing agent that is able to corrode copper and its alloys quite easily.…”

Controlled porosity and pore size of nano-porous gold by thermally assisted chemical dealloying – a SAXS study

“…This top-down etching process was demonstrated to fabricate porous metal materials with bi-continuous poreligament structures. [19][20][21][22] Chemical dealloying is a controlled corrosion process, naturally happening for metals exposed to environments and has been reported for a number of metal alloys, 23,24 such as copper, [24][25][26][27] gold, [28][29][30] silver, 31 magnesium or platinum. 32,33 These materials have been extensively used to form nano-textured or nano-porous metal-based materials.…”