Preparation and characterization of electroless Ni–Co–P ternary alloy on fly ash cenospheres

The process of ternary Ni–Co–P alloy films deposited on fly ash cenospheres (FACs) through a modified electroless plating way is documented. A pretreatment of FACs by γ-aminopropyltriethoxy silane (APTES) was introduced prior to electroless plating, which improved the continuity and uniformity of the alloy films remarkably. During the plating process, three factors were taken into consideration to investigate the composition and the plating rate of the deposits: mole ratios of NiSO4/CoSO4, the sodium hypophosphite concentration and pH of the plating bath. The obtained Ni–Co–P alloy deposits were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The results suggest that the as-plated deposits were Ni–Co–P alloy microparticles, which transformed from amorphous state to crystal phases with the increase of calcining temperature. In addition, the electroless Ni–Co–P deposits exhibit soft magnetic properties at room temperature. The magnetic performances of the deposits would be ameliorated with the increase of the cobalt content of the coating and calcining temperature.

Research highlights
► Modified electroless method to plate Ni–Co–P alloy film on fly ash cenospheres.
► APTES (γ-aminopropyltriethoxy silane) as coupling agent.
► Silver nitrate as activator precursors.