The unique microstructures of nanoscale coatings are the reason for their superior properties in wear applications like cutting tools. By using chemical vapour deposition (CVD) a nano-lamellar AlTiN coating consisting of TiN and AlN was achieved by spontaneous self-organization during layer growth. These results suggested the investigation of the AlZrN system.

In this study, AlZrN coatings were deposited by CVD from ZrCl4 and AlCl3 precursors and reaction with NH3 at 950 °C. By changing the AlCl3:ZrCl4 ratio various layers with changing chemical composition could be deposited. The layer thicknesses were determined gravimetrically and by means of dome grinding. To verify the microstructure of the coatings transmission electron microscopy (TEM) and X-ray spectroscopy (XRD) were applied. The coatings showed the formation of nano-crystalline phases but additionally some amorphous phases. Pillar structures were found throughout the coatings, with a higher crystallinity in the pillar compared with the surrounding material (Figure 1). Regarding the transition area between the substrate and the deposited coating, differences in the elemental composition as well as the crystallinity compared to the bulk of the coatings were observed. Depending on the elemental composition, the formation of hexagonal AlN or cubic ZrN was found. Additionally a shift of the respective lattice parameters was observed by x-ray diffraction, which indicates the incorporation of other elements in the crystal lattice.

With the obtained results new information on the microstructure as well as the crystallinity of AlZrN coatings with varied Al/Zr ratios was received, which can further help to customize coating properties such as the phase formation accompanied with different crystal structures.