無電解ニッケルめっきにおよぼす磁場の影響

抄録

It was hypothesized that in the absence of the action of the Lorentz force (rotary motion of an electrolyte) would be very small, and the influence of magnetic fields on redox reactions would show clearly. A low temperature plating bath including 26.7g·dm^-3 of nickel hypophosphite, 12g·dm^-3 of boric acid, 2.6g·dm^-3 of ammonium sulfate and 4.9g·dm^-3 of sodium acetate was adjusted to pH 6.0 with acetic acid or ammonia water. The amount of nickel deposition was inhibited and at a magnetic flux density of 0.2T its effect increased the deposition time to 12% after 1 hour and 26% after 12 hours. The inhibition effect after 12 hours was strongly apparent at a magnetic flux density of 0.1T, with the amount deposited was decreasing by about 20%. At magnetic flux densities over 0.1T, there was virtually no change in the effect. In terms of the crystal orientation of nickel deposits, the (220) face was more affected by the magnetic field than the other faces. Crystal orientation was relatively less as magnetic flux density became large, but deposition time and crystal orientation were not affected by magnetic field. Long-term change in spontaneous electrode potential was not influenced by a magnetic field in the plating bath, and no change was observed in deposition potential due to magnetic field in polarization curves in the plating baths. In nickel hypophosphite solutions, deposition potential was shifted by about 0.035V in the negative direction. Irrespective of whether a magnetic field was present or not, deposits exhibited adhesion and a lustrous appearance. In the absence of magnetic field, the deposits included 4.8% phosphor, and with a magnetic field present, phosphor content decreased to 3.6%, an inhibition ratio of 25%. It was concluded that magnetic fields exert an influence on the oxidizing reaction of hypophosphorous acid.