Abstract
Dezincification of commercial brass was studied in sodium chloride (NaCl) solutions at various temperatures (25°C to 80°C) and salt concentrations (3.5% and 16% NaCl) using electrochemical techniques, scanning electron microscopy, energy-dispersive spectroscopy (EDS), and inductively coupled plasma (ICP). The increase in temperature shifts the free corrosion potential in the active direction to an extent that increases with an increase in the salt content. The rate of alloy dissolution increases with temperature and salt concentration, which indicates an activated process promoted by the chloride ions. The alloy undergoes simultaneous dissolution of Zn and Cu at low temperatures, low salt content, and active potentials, with no significant change in the composition of the alloys surface. However, strong dezincification was documented at 60°C and 80°C in the presence of 16% NaCl, where copper formed about 95% to 98% of the alloy surface. Mild dezincification was observed at 80°C in the 16% NaCl only at active potentials and in 3.5% NaCl at relatively noble potentials. High salt content causes considerable etching of the surface. A dezincification ratio (DZR) was proposed and evaluated as a measure of the extent of change in the composition of the alloy surface.
