The formation process of nanocrystalline permalloy by electroplating and optimization the surface conditions for alloy coatings

Permalloy (80%wt. Ni, 20%wt Fe) coatings were electroplated in 25°C by applying current density of 100 mA/cm2 in a bath with the pH of 3.8. A mechanical stirrer (160 RPM) was used during 8 hours electroplating. Saccharin was used as a stress reducing agent and a grain refiner to gain nanocrystalline coatings. The pH of plating was controlled by boric acid as a buffer. The SEM images of surface of coatings indicated the different processes of forming the cauliflower structure including nucleation, three dimension growth and integration of crystals. To study the effects of different parameters on the roughness of coatings, various temperatures (25, 45, 75°C), different times (3, 8 hours), different amounts of saccharin in the bath (10, 5, 3, 1g/L) and two different types of agitation (magnetic and mechanic stirrer) were investigated. The results of roughness test showed that decreasing the plating time and the amount of saccharin in the bath decrease the surface roughness. In addition, increasing the temperature and using magnetic stirrer caused a decline in the surface roughness. Increasing the temperature would also change the alloy composition.