Evaluation of Corrosion Resistance and Characterization of Ni-Cr Coated Structure Using Plasma Spray Coating for Marine Hulls

Abstract

Corrosion is a natural process which gradually destructs the materials with their environment by chemical or electrochemical means. Mechanized boat hull structures used in fishing were made up of mild steel plate where it corrodes easily within 2 to 6 months due to the marine environment. To prevent this corrosion, coating can be performed on the outer surface of the hull structure. For many decades, the hull structure is made up of mild steel with the thickness ranging from 6 to 20 mm depending upon the usage in marine and structural applications due to its high specific mechanical and thermal properties, However, it corrodes due to the nautical environment and so the paint was coated on the surface, where these paints react with sea water within 6 to 12 months and start corroding the boat hull structure. So, coating with a highly corrosive-resistant material in marine environment can be used on the surface of the hull structures to protect from corrosion. Moreover, the partially immersed mechanized boat hull structure and the engine room corrode due to seawater and heat liberated. In the present work, an attempt was made with micro particle coating on the surface of the hull structure to prevent the corroding marine hull structure, thereby enhancing the properties and life of the structures and reduce the maintenance cost leading to economic growth of the fishermen. Ni-Cr powder was synthesized using heavy ball milling method and the required size was obtained. The coating was carried out on the surface of the hull structure using plasma spray techniques and the prepared specimens were sized using EDM-CNC based on ASTM standards. Various tests like surface roughness, hardness properties (Rockwell, Brinell, Vickers and Micro Vickers), corrosion tests (salt spray and general weight loss method) and characterization using SEM, EDAX, XRD, and FTIR were performed with uncoated, paint coated, and Ni-Cr coated surface. The obtained results were compared and it reveals that the utilization of Ni-Cr coating enhances the properties of marine structures from the existing metal in use and divulges that this coating reduces the corrosion rate, improves structure life, reduces maintenance cost, reduces the lapses in fishing trips, and increases the economic growth of the fishing community.