Osamu Takano

Soft Magnetic Films by Electroless Ni‐Co‐P Plating

An electroless Ni-Co-P plating solution was developed for preparing soft magnetic thin films. In this plating process, the optimum bath composition and operating condition were obtained by investigating the effect of operating conditions on deposition rate, film composition, and magnetic properties. Soft magnetic films with low coercive force (lower than 80 A m -1 ) and high squareness (higher than 0.8) were prepared from these electroless Ni-Co-P plating processes. The alloy film deposited from the optimum bath condition consists of fine-particulated crystallites.

Electroless Ni-S-P Alloy Plating. Electrode Properties.

The structure and polarization properties of deposits containing a high level of sulfur, obtained from electroless Ni-S-P alloy plating baths by the addition of sodium thiosulfate were investigated.The following results were obtained:1) When the phosphorus content of the deposits was changed, the hydrogen overvoltage scarcely varied. As the phosphorus content in the deposits increased, their corrosion resistance was improved.2) Examination of X-ray diffraction patterns revealed that particle size increased with increasing sulfur content and decreasing phosphorus content in the deposits.3) Examination of polarization curves showed that hydrogen overvoltage decreased with increasing sulfur content in the deposits.4) The corrosion resistance of the deposits improved as the sulfur content in the deposits increased to 0.5%∼0.8%, and thereafter decreased.

The Electrical Contact Properties of Electroless Nickel Alloy Deposits

The electrical contact properties of electroless deposits of Ni-Cu-P alloy containing metallic copper of low electrical resistance, and of Ni-Sn-P alloy containing metallic tin, which had aroused interest in the electrical resistance of its oxides, were investigated. The wear resistance of the deposits was also investigated using reed awitches.

Corrosion Protective Properties of Electroless Co-Ni-P Alloy Plating

The corrosion protective properties of electroless Co-Ni-P alloy plating were examined in 5% NaCl solution. The corrosion resistance of Co-P film was better than that of Ni-P film. The corrosion potential of the films was less noble in the order Ni-P, Co-P, Co-Ni-P, and contact corrosion current density in circuits constructed of deposited film and an Fe plate decreased in the same order.Thus the amount of dissolution of Fe substrate in the corrosive solution decreased and the corrosion protective properties of the depositions on the Fe substrates improved in the same order.