IN-DEPTH ANALYSIS OF ELECTROLESS NICKEL-PLATING LAYERS BY GLOW-DISCHARGE EMISSION-SPECTROMETRY

Glow discharge emission spectrometry with a Grimm-type lamp was applied to elemental analysis of electroless nickel layers deposited from hypo-phosphite plating baths. The plating layers contain ca. 8 weight per cent phosphorus. The depth profile analysis of the as-deposited sample indicates the segregation of phosphorus at the surface of the plating layer. The depth profilings of heat treated steel substrates covered by electroless nickel coatings were also studied. The heat treatment at 750-degrees-C makes a more complicated structure of the layer, consisting of nickel-iron oxide layers, a nickel-phosphorus plating layer, and an iron diffusion zone.