Electrochemical evaluation of corrosion resistance of chromium plated nickel and copper tin alloys. A comparative study

Abstract

Engineering materials and composites are frequently exposed to aggressive and chemically toxic environments with high probability for rapid corrosion and consequent deterioration and catastrophic degradation. Occasionally, a new legislation regulates against the use of existing materials, necessitating thus development of new methodologies or new materials in order to reduce material corrosion rates. The aim of this study is to test the corrosion resistance of the copper tin alloy, a material that could replace nickel compounds, recently reclassified as suspected carcinogens. Standard sizes of pre-cut nickel and brass panels were produced and then plated with different thicknesses of copper tin alloy and chromium for additional protection. Evaluation of plated materials for corrosion rate and resistance was carried out using linear polarisation, electrochemical impedance and accelerated destructive testing. Corrosion testing of the materials assessed qualitatively and quantitatively, showed that corrosion resistance was dependent on a combination of factors, including the thickness of chromium plating, type of material, type of testing and duration in a corrosion chamber. While linear polarisation experiment was useful in establishing corrosion rate of sample, electrochemical impedance and accelerated destructive testing experiments assessed corrosion resistance of the materials.