Abstract:
Electroless deposits of nickel in hypophosphite-pyrophosphate solutions at 70ºC have been obtained and their anodic and cathodic polarization behavior in H2SO4 at room temperature has been examined. Hydrogen evolution rates on the electroless deposited electrodes were larger than on pure nickel. The rate of active anodic dissolution of the electroless deposits were lower than for the pure nickel substrates, but approached the rate of the latter as the plate thickness was decreased by electrodis solution. It has been observed that passivation of electroless nickel plated electrodes in H2SO4 could not be achieved. On the other hand, pure nickel readily passivated in the same solution. Deviations of the anodic behavior of the electroless deposits from that of pure nickel were larger for those deposits prepared in the low nickel plating baths. The differences in the anodic and cathodic polarization behavior between electroless nickel deposits and pure nickel have been attributed to the phosphorus in the former.
Reference:
DI GIORGI, Francisco; NOBE, Ken. Electrochemical and corrosion behavior of electroless deposited nickel. In: INTERNATIONAL CONFGRESS ON METALLIC CORROSION, 7., 1978. Rio de Janeiro. Proceedings… Rio de Janeiro: Ass. Bras. Corrosão, sd. v.1, p.375-86.
Electroless deposits of nickel in hypophosphite-pyrophosphate solutions at 70ºC have been obtained and their anodic and cathodic polarization behavior in H2SO4 at room temperature has been examined. Hydrogen evolution rates on the electroless deposited electrodes were larger than on pure nickel. The rate of active anodic dissolution of the electroless deposits were lower than for the pure nickel substrates, but approached the rate of the latter as the plate thickness was decreased by electrodis solution. It has been observed that passivation of electroless nickel plated electrodes in H2SO4 could not be achieved. On the other hand, pure nickel readily passivated in the same solution. Deviations of the anodic behavior of the electroless deposits from that of pure nickel were larger for those deposits prepared in the low nickel plating baths. The differences in the anodic and cathodic polarization behavior between electroless nickel deposits and pure nickel have been attributed to the phosphorus in the former.
Reference:
DI GIORGI, Francisco; NOBE, Ken. Electrochemical and corrosion behavior of electroless deposited nickel. In: INTERNATIONAL CONFGRESS ON METALLIC CORROSION, 7., 1978. Rio de Janeiro. Proceedings… Rio de Janeiro: Ass. Bras. Corrosão, sd. v.1, p.375-86.
