The morphology change of Co coatings prepared by cathode plasma electrolytic deposition

• Uniform and dense Co coatings were prepared by cathode plasma electrolytic deposition.
• The law to prepare high quality Co coatings by cathode plasma electrolytic deposition was proposed.
• The morphology of coating is determined by depositing rate and effect of plasma arcs.
• Low CoSO4 concentration and high H2SO4 concentration are required to obtain ideal coatings.

Co coatings were prepared by conventional electrode position and cathode plasma electrolytic deposition respectively in the electrolyte with different CoSO4 and H2SO4 concentration. The morphologies of coatings were investigated by optical microscope and scanning electron microscope. It is found that the morphology change of Co coatings prepared by cathode plasma electrolytic deposition is quite different from that of conventional electrodeposition. To obtain uniform and dense Co coatings by cathode plasma electrolytic deposition, lower CoSO4 concentration and higher H2SO4 concentration are required in the electrolyte, compared with that of conventional electrodeposition. Otherwise, the deposited Co coatings will be rough or dendritical in the electrolyte with higher CoSO4 concentration and lower H2SO4 concentration.