| AVS 54th International Symposium | |
| Advanced Surface Engineering | Monday Sessions |
| Session SE-MoM |
| Session: | Hard and Nanocomposite Coatings: Synthesis, Structure, and Properties |
| Presenter: | J. Patscheider, EMPA, Switzerland |
| Authors: | A. Pelisson, EMPA, Switzerland M. Parlinska-Wojtan, EMPA, Switzerland P. Schwaller, EMPA, Switzerland H.J. Hug, EMPA, Switzerland J. Patscheider, EMPA, Switzerland |
| Correspondent: | Click to Email |
Transparent nanostructured coatings of Al-Si-N were deposited by reactive DC magnetron co-sputtering of Al and Si targets in an Ar/N2 atmosphere at substrate temperatures between 200 and 500°C. The elemental composition was varied from pure AlN to Al-Si-N with 30 at.% of Si. The coatings were characterized by XPS, TEM, XRD, nanoindentation and UV-Visible spectroscopy. X-ray diffraction results suggest that the coatings consist of nanocrystalline h-AlN with substitutionally incorporated silicon for Si concentrations below 13 at%. At Si concentrations exceeding 13 at% the coatings are X-ray amorphous. In contrast to known silicon-containing ternary nitrides and to available thermodynamical data for the Al-Si-N system, this material shows no clear phase segregation during deposition into AlN and SiNx; instead an Al1-xSiNx solid solution is formed that coexists with SiNx for silicon concentrations above 6 at% Si. XRD and TEM analysis show that the crystalline material consists of elongated grains; the crystallite size decreases from 60 nm to about 10 nm upon addition of silicon. The average optical transparency of 1 micron thick coatings in the visible range of light approaches 100%. The hardness exceeds 30 GPa, with a weak maximum at 8-12 at.% of Si which corresponds to the lowest internal stress in the coatings (= 0.5 GPa). At this composition the elastic strain to failure H/E, or resilience, is increased by 50% by the addition of silicon to AlN.