POROSITY STUDY ON MICROSTRUCTURES OF NICKEL-CHROMIUM ALLOY PLATING ON COPPER SUBSTRATE

Porosity in coatings is a vital parameter for many engineering applications. Having a porous coating is good with respect to few aspects and bad with respect to others. One of the main applications of porous metal coating is in the field of membrane filters for oil water separation to deal with industrial waste water and off-shore oil spill. It is also used for electrolytic cleaning (purification) of water. Studying the nature of formation and development of pores is being carried out by many researchers to determine the parameters affecting the porosity of coatings. Optimizing the parameters to obtain a favourable coating with least defect is the idea behind these research topics. Nickel and chromium coatings are widely used for many industrial applications because of specific properties. Nickel-chromium alloy coatings offer better hardness, wear and corrosion resistance compared to individual nickel or chromium coatings. The alloy coatings are observed to be porous in nature compared to individual nickel and chromium coatings. Controlling the porosity of the deposition by varying the process parameters is a very interesting topic of research as it greatly influences the properties. In the present work, the coating microstructures of nickel-chromium alloys developed by electrodeposition techniques are analysed and evaluated using Field Emission Scanning Electron Microscopy (FESEM) for varying current densities and plating time resulting a good uniform coating with varying porosity