AN INVESTIGATION INTO THE CORROSION BEHAVIOUR OF ZINC AND CHROMIUM METALLIC COATING ON MILD STEEL SUBSTRATE

An investigation into the corrosion behaviour of zinc and chromium metallic coating on mild steel substrate is conducted. This is to show that using suitable coating is good in preventing corrosion on mild steel. This project is also done to compare which metallic coating is better for the mild steel substrate. The samples are grind and polished before they are coated. The samples are coated with different period of inunersion in plating bath to differ their coating thickness. Various tests are conducted to compare the coating in different parameters. Salt spray test, linear polarization measurement, hardness test, weight loss, surface roughness, and inspection of microstructures of the coating together with substrate are done according to ASTM standards. For this dissertation report, it is proven that adding coating will enhance the mild steel hardness and appearance. It will also greatly reduce the rate of corrosion of the mild steel substrate. With the increase thickness of coating, the mild steel corrosion rate will be improved. The project also proved that Chromium coating is superior to Zinc coating in terms of corrosion rate, hardness, and surface roughness. It can also be concluded that corrosion will cause loss of function and appearance towards the mild steel substrate such as decreased hardness and also increased surface roughness