Possibility of Applying Chromium Coat on Aluminium without Interlayer and its Corrosion Behaviour

In this research, the possibility of the applying chromium coat on a pure aluminium substrate without interlayer was investigated. It is mentioned in literature that due to the formation of oxide layer on the surface of the aluminium, interlayer is needed to apply chromium coat on it to improve the surface microhardness. Therefore, chromium coat applied by electroplating method and optimum process parameters were achieved at current density 60 A/dm2 within 45 minutes. Bright and uniform chromium coat was obtained under this condition. The surface morphology of that was studied by field emission scanning microscopy (FE-SEM) and atomic force microscopy (AFM). Finally, corrosion behavior of the optimum coat was investigated by polarization test and electrochemical impedance spectroscopy (EIS). Results show that significant improvement at corrosion resistance of the coated sample in comparison to pure aluminium where calculated corrosion rate is equal to 0.32 mpy. Also, it is seen that pitting corrosion had been occurred at the surface of the coated sample.

Keywords:

Chromium Electroplating , Pure Aluminium , Oxide Layer , Interlayer , Surface Morphology , Corrosion