Effect of surface roughness on glossiness and surface color for pure titanium and titanium nitride-coating surfaces

In this study, the effect of surface roughness on glossiness and surface color for a pure titanium and a TiN coating surface was investigated based on the experimental discussions. CIELAB (L*a*b* color system) was applied to the evaluation method of surface color. Specimens were machined so that the arithmetical mean roughness, Ra, is less than 1.0 μm. From the results of experiments, the arithmetical mean roughness, Ra, decreased, as the glossiness, Gs (60°), increased. Especially, the glossiness value in the roughness range Ra?0.2 μm was distributed from 50 to 400. Moreover, the arithmetical mean roughness, Ra, decreased, as the lightness, L*, and a, b chroma, C* ab , decreased. The TiN coated surface with vividness had a pronounced tendency to decreasing lightness, L*, and a, b chroma, C* ab . This was attributable to the smaller difference of elevation of the spectral reflectance curve by reason that the short wavelength was diffused more than the long wavelength.