Various typical polymer materials, such as nylon and polyethylene, have received much attention due to their attractive outstanding properties, including good corrosion resistance and low friction coefficient. In this research, polyamide 6, polyamide 66, polyamide 46, polyoxymethylene, high-density-polyethylene and low-density-polyethylene were used as substrates, and they were coated with a diamond-like carbon (DLC) film by a magnetron RF sputtering technique. Their tribological properties were evaluated by a ball-on-disk type friction test technique. The results show that the wear properties of the polyamide 46, polyoxymethylene and high-density-polyethylene coated with DLC film had not been improved. However, the friction coefficients decreased by 1/10 for polyamide 6, 1/6 for polyamide 66 and 1/2 for low-density-polyethylene in the friction tests after they were coated with the DLC film. This is thought to be because the adhesion between the specimen and the polyamide 66 ball were small, due to the stable chemical properties of DLC film.
A novel magnetic abrasive with light weight was developed by using electroless Ni-B-diamond composite coatings on a lightweight resin particle (specific gravity : 1.1). The newly-developed magnetic abrasive is expected to take care of the insufficiency known to exist in the present technique. Conventionaly used heavy magnetic abrasives like iron produce a strong power in the process of magnetic field-assisted finishing and are therefore not suitable to be used for polishing workpieces with soft material or fine parts that need polishing. The newly-developed magnetic abrasive was practically applied in the process of magnetic field assisted finishing, so that an aluminum plate was machined from the initial roughness (Ra) 0.33μm to 0.16μm.
Composite electrodeposition of TiO2 particles in amorphous Ni-Mo alloy matrices was carried out using aqueous citrate solutions (pH5.0) where anatase- or brookite-TiO2 particles were suspended. A white and uniform composite coating was obtained from a solution containing 200g dm−3 of TiO2. The composition of the Ni-Mo alloy matrices remained unaltered with the inclusion of TiO2. Although the uptake of TiO2 did not exceed 0.1wt.%, the resulting Ni-Mo/TiO2 layer exhibited the ability to decompose gaseous NO in the air or Methylene Blue in water. It was suggested that the anti-corrosive ability of the Ni-Mo layer is improved by the inclusion of TiO2 in the layer.