Corrosion of Copper in a Thin-Solution Layer of Concentrated Aqueous Solution of Lithium Bromide
Atsushi NONAKA and Hidemasa NONAKA
Abstract:In order to evaluate the corrosion of copper which is used as an absorber vessel material in the absorption refrigeration cycle, electrochemical measurements of copper in the condition of a thin-solution layer, which is 1 mm in thickness, of concentrated aqueous solution of lithium bromide in argon atmosphere were made. As a result, values of corrosion rate in the condition of a thin-solution layer were 3 to 6 times larger than in the immersed condition regardless of whether there was an inhibitor or not. This difference seems to be due to the following reason. As the argon gas phase above the solution contained a little air (oxygen), the oxygen concentration was higher in the condition of a thin-solution layer than in the immersed condition. Therefore, the values of free corrosion potential in the condition of a thin-solution layer became more noble than in the immersed condition, and cathodic diffusion limit current density in the condition of a thin-solution layer increased, compared with that in the immersed condition. Key Words:Thin-solution layer, Corrosion rate, Polarization curve, Polarization resistance, Corrosion inhibitor, Lithium bromide, Absorption cycle