Ni-Al₂O₃及びNi-ZrO₂分散めっきの生成条件

抄録

Electrodeposition of Ni-Al₂O₃ and Ni-ZrO₂ from a Watts nickel bath has been studied to determine the factors affecting the codeposition of the oxide particles into nickel matrix. The amount of the oxide particles codeposited into the nickel deposits was found to increase linearly with decreasing pH of the plating bath under the constant current density. Higher content of the oxide particles in the deposits was observed at lower current densities. The surface appearance and hardness of the composite coatings as well as the contents of the oxide particles were affected by the organic cations such as fluorescent dye or crystal violet. It was confirmed that nickel ions, protons, and/or organic cations are adsorbed on the oxide particles bringing about the positive surface charge, and thus they promote the entrapment of the oxide particles into the nickel deposits. Codeposition of the oxide particles into nickel matrix can be explained by the hydrodynamic transport of the particles and the field-assisted electrosorption of the oxide particles to the cathode, and finally by the electrochemical entrapment of the particles into the growing crystal.