An environmentally friendly chromium-free Ni-W-P alloy plating was prepared as an alternative to hard chrome plating by electroless plating. The alloy plating film, which was electroless plated in an alloy plating bath containing 0.22 M Na₂WO₄, contained 16 mass% W. The alloy plating film calcined at 600 °C had a NiO layer (0.5 μm), a Ni-W-P layer (10.8 μm), and a Ni layer (1.0 μm) from the surface. The Vickers hardness of the plating film calcined was over 1000 Hv. Ni-W solid solution crystals and Ni₃P crystals were formed in this hard plating film. The corrosion potential of the alloy plating film was found to be 0.32 V greater than that of the nickel plate, which indicates a potential for improvement in corrosion resistance.

The influence of three types of surfactants, the nonionic surfactant polyoxyethylene(23)dodecyl ether (Brij-35), anionic surfactant sodium dodecyl sulfate (SDS) and cationic surfactant dodecyl trimethyl ammonium chloride (DTAC), on the dyeing of silk fabric with natural dyes extracted from brown onion skin, was investigated. The surface tension, zeta potential and absorbance of aqueous solutions containing different concentrations of the three dodecyl-tail surfactants, with and without the dyes, were measured. The surface tension of the solutions containing SDS and DTAC decreased with the addition of natural dyes, suggesting that attractive interactions between the ionic surfactants and dyes further disrupted the cohesion forces between water molecules. The colors of the fabrics dyed with and without the three types of surfactants were compared and found to be paler with the addition of SDS and DTAC. The absorbance of the dye solutions containing DTAC and the color of the dyed fabrics were compared by varying the DTAC concentration. The absorbance reached a minimum at a DTAC concentration of 15.0 mmol/L, which was same as the critical micelle concentration (CMC). On the other hand, the color of the dyed fabrics became paler with increasing concentration of DTAC. The results are discussed based on the distributed state of the dye molecules in the solution and the interactions among the dye, surfactants, and fibers. This research contributes to understanding the complicated interactions among dyes, fibers and surfactants.