Preparation and characterization of Ni–P/nanodiamond coatings: Effects of surfactants

In this study, the effects of different concentrations of surfactants on the properties of the Ni–P/nanodiamond (ND) coatings were investigated. Sodium dodecyl sulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB) were used as the surfactants. Morphology, microhardness and some tribological properties of the coatings were evaluated and compared. Results showed that the composite coatings modified with high concentrations of SDS had smoother surface morphologies than the ones modified with CTAB and low concentrations of SDS. Moreover, it was observed that these coatings had the highest microhardness and wear resistance as well as the lowest friction coefficient (FC) among the coatings. It was found that the effect of NDs on the microhardness of as-plated composite coatings and the ones annealed at 200 °C/3 h was not significant, but became significant when heat treated at 300 °C/1 h and 400 °C/1 h.

► Surface morphology is affected by concentration and type of surfactant.
► 3 mg/l of SDS gives the smoother surface morphology and lower friction coefficient.
► Among the three annealing conditions, “400 °C/1 h” results in highest hardness.
► The hardness of amorphous coatings is not affected by nano-diamond incorporation.