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PVD and CVD coatings usually display non-equilibrium phases due to the high quenching rates involved in these processes. Nevertheless, we found from XPS studies performed on Ti-B-N coatings of various composition that type and relative amount of Ti-N, Ti-B and B-N bonds are in good agreement with the predictions of the phase diagram. X-ray diffraction studies corroborate these findings for the Ti-containing phases, but also show that the coating material is nanocrystalline.
The phase diagram of the Ti-B-N system is characterized by an extended central part where two hard phases (TiB(2) and TiN) and a soft and lubricating phase (h-BN) coexist. Assuming that Ti-B-N coatings display also these phases and interesting possibility is offered to tailor the coating material by suitably combining the hard and soft phases. Two different types of Ti-B-N coatings were synthesised based on phase diagram considerations: ultrahard and tough coatings by selecting a composition corresponding to a phase diagram region where only two hard phases coexist in about equal amounts; less hard coatings which in addition to the hard phases also contain a soft phase.
The tribological properties of these coatings were investigated by scratch test and pin-on-disk experiments and hardness was determined by nanoindentation. .

Additional information

Authors: GISSLER W, JRC Ispra (IT);MOLLART T P, JRC Ispra (IT);GILMORE R, JRC Ispra (IT)
Bibliographic Reference: Article: Protective Coatings and Thin Films Synthesis, Characterisation and Application, Kleuver Academic Publishing (1996)
Record Number: 199610870 / Last updated on: 1996-09-16
Original language: en
Available languages: en