Electroless Ni-Co-P alloys on glass fibers with sodium hypophophite as a reducing agent and sodium citrate as a complexing agent in an alkaline bath was studied. A kind of silane coupling agent was used during its pretreatmeat. Plating rate was determined by measuring the weight of glass fibers after plating. The effect of deposition parameters, such as mole ratios of CoSO_4/(CoSO_4+NiSO-4) and pH, on the composition and the plating rate of the deposits were examined. The crystallization behavior of Ni-Co-P alloys was studied by using differential scanning colorimetry (DSC) and X-ray diffraction (XRD). It was found that all of the three exothermic peaks in DSC curves alter distinctly as the mole ratios of CoSO_4CoSO_4+NiSO_4) increase. When the concentration of sodium hypophophite is not below 16 g l~(-1) in the plating bath, the structure of the as-plated Ni-Co-P alloys plated at all conditions is amorphous. The deposit transformed into Ni_5P_2 and Ni_(12)P_5 phase after heat treatment at 300 deg C and 420 deg C, but they disappear and stable Ni_3P appeared after sintering at 480 deg C.
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