Abstract: The morphology, crystalline state, composition elements and their depth, profile and valence state were studied by scannfing electron microscopy (SEMi), x-ray diffractometry (XRD) and electron spectrometry (XPS and AES). The result showed that the low phosphorous electroless nickel coating has a smooth lamellar structure, composed of Ni and Ni₂P of low crystalline state, but they were transformed into Ni and Ni₃P of complete crystalline state after heat treatment at 350℃ for 1h.The phosphorous and nickel in low phosphorous eleetroless nickel coating were in zero valance state, with binding energy being 129.1 eV and 852.3 eV respectively. The compositions(A.C.%) of the Ni-P coating were Ni 85.4%, P 10.1%, O 4.5% as obtained after the constant composition region of the AES depth profile curves of the Ni-P coating.

Key words: electroless nickel plating, Ni-P alloy, XPS, AES, XRD