Jet electrodeposition of nanocrystalline nickel assisted by controllable friction

A controllable friction auxiliary method (CFAM) was developed to improve the quality of a coating surface prepared through flexible friction-aided jet electrodeposition (FFAJED) at a high current density. A rolling nozzle was also designed. This nozzle can provide controlled pressure constantly during deposition so that the proposed method can forcibly restrain the rapid growth of the coarse grains. The influence of different pressures and cathode scanning speeds on coating surface quality was discussed, and the optimum parameters of the method were determined. With the optimum parameters, the effect of different current densities on coating surface quality was studied. Results show that when the rolling pressure is 5 N and the scanning speed of the cathode is 860 mm/min, the surface quality of the coating is excellent. No obvious coarse grains, defects (e.g., pinhole or nodules), and apparent traces of friction were observed. The magnetic properties of Ni coating were improved too. The upper limit of current density in the preparation of Ni coating by CFAM reached 200 A/dm2, which is 1.54 times that of traditional jet electrodeposition (130 A/dm2) and 1.43 times that of FFAJED.