Electroless nickel-phosphorus plating on SiCp/Al composite from acid bath with nickel activation

An electroless Ni-P plating process on the surface of aluminum matrix composite reinforced with 70 vol.% SiC particles (SiCp/Al) has been investigated in order to improve its surface characteristics. The new method of nickel activation is used to render the surface of such composite autocatalytically active towards the metal deposition in electroless plating solution. SEM, EDAX and XPS clarify the morphology, component and chemical state of the activated and coated SiCp/Al composite. The surfaces activated with the nickel are covered by a layer of Ni-P film, and the adsorbed species are reduced into neutral nuclei in the electroless bath. On these energetically active sites, nickel ions in the plating solution develop into neutral nickel atoms and form uniformly distributed nucleation centers of nickel islands. In this case, the number of grains still continuously increases until the deposits become continuous. The effect of the deposition conditions and the concentrations of nickel ions, hypophosphite ions and acetic acid on the rate of deposition are measured. The influence of some reagents concentrations on the phosphorus content is investigated. This research has been successful in allowing the development of approaches for the electroless metallization of such composite material by the nickel activation. (C) 2007 Elsevier B.V. All rights reserved.