Abstract:In the present investigation, ternary Ni-W-P deposits were prepared on the mild steel (1015) substrate using electroless plating by varying sodium tungstate. Surface morphology, microstructure, and the microhardness of electroless Ni-W-P deposits were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and a MH-6 Vickers diamond indenter, respectively. The results demonstrated that the bath concentration plays a significant role in obtaining ternary Ni-W-P deposits containing various composition of phosphorus and tungsten, which decides the surface morphology and the structure. Although nodular formation is a common feature of electroless Ni-W-P deposits, composition of W decreased the P content of these deposits and hence changes the content of the nanocrystalline phase. The co-deposition of tungsten in the deposits increased the microhardness due to the solid solution strengthening of nickel induced by tungsten in the deposits and resisted regional plastic deformation. Moreover, studies on phase transformation behavior carried out by differential scanning calorimetry (DSC) showed that Ni-W-P deposits with high W content exhibited higher crystallization temperatures. Further fouling experiments indicated that the Ni-W-P deposit surfaces with different W content inhibited the adhesion of fouling compared with the mild steel surface. However, we found there is not a necessary relationship between the fouling adhesion rate and surface roughness of the ternary Ni-W-P deposits, but is intimately related to the W content.