STUDY OF ELECTROLESS NI-P DEPOSITION ON ALUMINUM

The investigations performed have shown that the deposition of Ni-P on aluminium starts by nucleation of nickel primarily at grain boundaries and at defects present on the aluminium surface. The shape of the deposited nuclei is hemispherical. These nuclei serve as a catalytic surface for Ni-P deposition. The process of electroless Ni-P deposition continues on deposited nickel nuclei. The Ni-P nuclei are observed to have the same hemispherical shape as the nickel nuclei. The growth and coalescence of such nuclei result in a continuous layer of Ni-P on the aluminium surface. X-ray analysis of the as-plated deposits have shown the presence of a clearly pronounced extended peak corresponding to nickel. In the small angle range a broadened diffraction line with two small extended peaks is present but these are difficult to identify. After heat treatment the deposits have a very well-defined crystal structure and it was confirmed that two crystalline phases-nickel and Ni3P-were present. © 1979.