The physical and chemical properties of electroless nickel-phosphorus alloys and low reflectance nickel-phosphorus black surfaces

Novel insights into the manufacture of nickel-phosphorus black surfaces by chemical etching of electroless-deposited Ni-P alloy has been achieved by examining the influence of pre-etch phosphorus composition and etching method on the resulting morphology, composition and reflectance of the black surface produced. An optimum phosphorus composition and etching regime to produce low reflectance blacks of 0.4% or lower in the visible region is proposed. Cross-sectional analysis of the etched surface has allowed, for the first time, an accurate determination of the scale of the enhanced morphologies produced and the thickness of the oxidised black layer itself. AFM studies have also provided information on the phase structure of the as-deposited Ni-P alloy.