EXPERIMENTAL INVESTIGATION OF CORROSION OF COATED CAST IRON ROTORS IN THE AUTOMOTIVE INDUSTRY

Electric and hybrid vehicles uses regenerative braking, where application of the brake triggers the electric motor to work as a generator to produce electricity, which in turn charges the battery. This results in much less use of the friction brake, changing the corrosion and wear behavior of the rotor surface. There is a need for research on this topic, since fully electric or hybrid vehicles are replacing combustion engines due to concerns about global warming and climate change. Here the corrosion behavior of coated cast iron vehicle rotors in 3.5wt% NaCl is studied. The corrosion study has been performed using electrochemical methods such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). All the coated samples were provided by Pure Forge Rotors. Based on the results from SEM and EDX, the coating is atomic forge proprietary coating, and the base material is gray cast iron. Our primary objective is to study the corrosion behavior of coated, non-coated and friction-tested samples. CV experiments indicate a shift in the corrosion potential and corrosion current density due to changes in the nature of the exposed surface. Cross-sectional SEM showed the thickness of the coating to be 16-23 µm. After friction testing, the friction layer created by rubbing the brake pad over the rotor plays a role in corrosion resistance, but this depends on the type of brake pad material (i.e. semi-metallic, non-asbestos organic and low metallic). Results showed that friction film that forms after testing against non-asbestos organic pads provides the highest corrosion resistance amongst the three brake pad materials