X-Ray Photoelectron Spectroscopy of Chemically Deposited Amorphous and Crystalline Ni-B Coatings

The chemical state of elements and the composition of surface and bulk layers of Ni-B coatings with the volume concentration of boron of 3.7 and 27.1 at. % obtained by electroless catalytic reduction are studied with x-ray photoelectron spectroscopy combined with layer-by-layer profile analysis. Up to 90% of nickel and 80% of boron are shown to be reduced on the surface of the coatings. The effect of the conditions of heat treatment in a vacuum and in air on the composition of the surface layer is analyzed. The original nonuniformity of the in-depth distribution of the elements is found to be most of all affected by heating in air at a temperature of 700°C that provides the surface formation of a B^sub 2^O^sub 3^ oxide layer containing no nickel. A stabilized composition of the alloys is observed at a depth of 10 to 60 nm depending on the conditions of heat treatment.[PUBLICATION ABSTRACT]