New Trends in Decorative Coatings 2 $ ? 6 ?
ecorative coatings applied with D . . sputter ion plating processes have become a widely accepted application for vacuum technology. Although the deposition itself is only one important step among others, indusmal decorative applications require a reproducible and productive coating system. Leybold, as a system manufacturer, is featuring machines with a high level of up-time as well as an extraordinary sales service. In addition, such equipment is able to control all manufacturing steps including the choice of substrate material, the proper machining of it, the advisable heat treatment, the correct surface machining, the appropriate electroplating and the right precleaning. All these factors have an important influence, since a successful product does not depend solely on film properties. All system features required in the performance portfolio need to be fulfilled. In some circumstances, features required for a satisfactory coating can only be determined in extensive field tests.
Decorative properties and chemical composition of hard coatings
Transition metal compounds (nitrides, carbides, etc.) find increasing use as decorative coatings combining intensive colours, high wear resistance and good corrosion resistance. While golden TiN and dark-grey TiC are limited in their colour variation, the addition of a second metal or a second metalloid widens the spectrum of decorative colours, e.g. to dark blue with (Ti, Al)N. In the search for new colours, a number of nitrides of binary IVa metal-based alloys were deposited by reactive magnetron sputtering. The correlation between colour and stoichiometry was determined by surface analytical methods. Proper selection of the process parameters (target composition, N2 flow rate, etc.) results in coatings with different colours exceeding the conventional spectrum of decorative coatings.
Reactive radio frequency sputter deposition of higher nitrides of titanium, zirconium, and hafnium
Higher nitrides of Ti, Zr, and Hf have been prepared by reactive rf sputtering of Ti, Zr, and Hf metals in a pure nitrogen atmosphere. The electrical and optical properties of these films are highly dependent on two deposition parameters, namely, the substrate temperature and the target voltage. We find that at each particular target voltage, there exists a critical temperature below which the higher nitride phase can be deposited and above which the phase cannot form. This suggests that the higher nitride phase (which is speculated to be an ordered defect structure) is metastable and is not energetically favored at high processing temperature or at high input power. At 2000 V target voltage, this critical temperature is determined to be approximately 200 °C for Hf–N, 25 °C for Zr–N, and is unknown for Ti–N system. The optical band gap of the ZrNx films decreases from 5.31 to 1.66 eV as the substrate temperature varies from −196 to 750 °C. Thermal analyses, using modulated beam mass spectrometry for monit...