Colorimetric properties of ZrN and TiN coatings prepared by DC reactive sputtering

The purpose of this work was to determine the dependence of the colorimetric properties of TiN and ZrN films on the sputtering conditions, especially on N2 and Ar partial pressures. The color of films was evaluated quantitatively by means of the chromaticity coordinates x and y, and the luminous reflectance Y. The colorimetric study has provided the following conclusions: (1) The color of ZrN coatings is more sensitive than that of TiN coatings to nitrogen partial pressure. (2) The bright gold color of ZrN coatings can be obtained by sputtering, even at the relatively higher pressure of 0.3 Pa (at high argon flow rate). On the other hand, a bright gold color for TiN coatings is only observed at the lower pressure of 0.15 Pa (low argon flow rate). (3) ZrN coatings can be made to exhibit the golden color, which is as bright as 24-carat gold, but slighter whitish, and TiN can be made to show the golden color, which has the same hue as the gold, but of slightly lower brightness. (4) Oxygen content in TiN coatings increases with increasing argon partial pressure. This tendency corresponds to the dependence of luminous reflectance and resistivity of this material on the argon partial pressure.