Abstract
The composition of the bath was 40g/dm3 NiSO4·6H2O, 50g/dm3 C6H5O7Na3·2H2O and 35g/dm3 NaPH2O2·H2O. Bath volume was used 50cm3. Substrate was an oxgen-free copper plate and its active area was 1cm×5cm×2. Two methods of ultrasonic irradiation were used. One was irradiation during plating, the other was one hour irradiation before plating (ultrasonic treatment bath). The deposition rate of Ni-P film increased with the ultrasonic irradiation. The most efficient was ultrasonic irradiation during plating, followed by ultrasonic treatment bath then non-ultrasonic irradiation. The most efficient frequency was 45kHz. P content of Ni-P films was reduced with ultrasonic irradiation in the order 100>28>45kHz. P content was reduced with increasing thickness at 45kHz. But P content increased in the ultrasonic treatment bath. P content increased under 2.5μm, increased steadily from 3 to 6μm and increased slowly over 6μm in the non-ultrasonic and ultrasonic treatment baths. Hardness increased with ultrasonic irradiation, in the order 100kHz (81Hv)<28kHz (88Hv)<45kHz (96Hv). Corrosion resistance increased with the ultrasonic irradiation, and incresed with heat treatment.
