The effect of ethylene glycol and diethylene glycol additives on the quality of nickel coating on stainless steel substrate by electrodeposition method

Abstract

The additives have a great effect on the quality of the nickel coating including brightness and thickness in the process of electrodeposition. In this research, Watts nickel bath conditions are studied in the presence of ethylene glycol and or diethylene glycol as an additive on the quality of nickel coating on stainless steel substrate. The method of one variable at a time is used to optimize the conditions. The brightness of the nickel coating is investigated using smartphone imaging and image processing in MATLAB software and also the thickness of the coating are measured by a thickness gauge. A nickel coating with brightness 94% and thickness of 18 micrometers is obtained in optimized conditions including 120 g/L of diethylene glycol and or 50 g/L of ethylene glycol, pH 4.5, time 20 min., temperature 45 oC and current density 6 A/dm2. The technique of scanning electron microscope energy diffraction spectroscopy (SEMEDS) is used to study the surface morphology and analysis of coating elements. The obtained results showed the uniform distribution of nickel coating with 100% purity. The results of X-ray diffraction (XRD) also showed that the nickel coating has an fcc crystal structure. The results of the polarization curves indicated an 83% reduction in the corrosion rate of the nickel coating in the NaCl medium.

Keywords

• watts bath
• nickel coating
• ethylene glycol
• diethylene glycol
• electrodeposition