Organic and inorganic corrosion inhibitors for copper in HNO 3 studied by two methods

Abstract

The dissolution of copper in HNO₃ solution has been studied by the thermometric technique. Free dissolution of copper in HNO₃ is assumed to take place accordingto an autocatalytic mechanism involving the formation of HNO₂. All the amino compounds added inhibit the dissolution process because of adsorption and/or destruction of HNO₂. Addition of inorganic ions also inhibits the dissolution of copper to different extents, except for NO₂ ⁻ which accelerates corrosion. It is of interest to note that the Cl⁻ ion, which normally acts as a pitting corrosion agent, functions in the present case as a corrosion retardant. Parallelism between corrosion assessment by the thermometric technique and by the weight loss method is established.