Analysis of corrosion resistance of nano structured Co-W coatings through electrodeposition technique coated on the surface of mild steel

Abstract

Mild steel, is used for various applications in the mechanical industry due to its formability and machinability. However, one aspect of mild steel that needs improvementis corrosion resistance. In the present work, a nano structured thin layer of Co-W metal alloy is deposited on the surface of mild steel at two different bath temperatures of 35 ℃ and 70℃ through electrodeposition technique to enhance the mechanical properties of mild steel at constant current density of 10 mA/cm2.Co-W coatings were deposited over a period of 30 minutes at the pH value 6. All the coated samples were subjected to the structural and mechanical characterizations like Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Analysis (EDS), X-ray Diffraction pattern (XRD) and electrochemical analysis. The structural analysis results of Co-W coated mild steel revealed that the Co-W coatings were crack free, bright, and uniform and all the coatings exhibited 92% of Co content with 8% of W content. Through XRD result, it was concluded that all the coatings exhibited the crystalline nature and found that the crystalline size was few tens of a nanometer with cubic crystalline structure. The corrosion behavior of Co-W coated mild steel was analyzed using electrochemical workstation method and the respective corrosion resistance of coated mild steel wascalculated. The film coated at 35 ℃ exhibited the polarization resistance of 267 Ω and the film coated at 70 ℃ exhibited the polarization resistance of 325 Ω. From the electrochemical studies of Co-W, it is concluded that the Co-W thin films coated at 70 ℃ exhibited the high corrosion resistance as compared with the film coated at 35℃.