Phase Formation in the Ti-Al-Mo-N System during the Growth of Adaptive Wear-Resistant Coatings by Arc PVD

Ti-Al-Mo-N coatings have been grown by arc PVD at different bias voltages, V-b, applied to the substrate and partial pressures of nitrogen reaction gas, p(N-2), in the working chamber. The coatings have a nanocrystalline structure, with an average grain size on the order of 30-40 nm and a layered architecture made up of alternating layers based on a (Ti,Al)N nitride and Mo-containing phases of thickness comparable to the grain size. It has been shown that the phase composition of the coatings depends on V-b and p(N-2): raising the energy of deposited ions by increasing V-b from -120 to -140 V, as well as raising p(N-2) from 0.3 to 0.5 Pa, leads to a more complete molybdenum nitride formation during coating growth, which causes a transition from (Ti,Al) N-Mo-Mo2N compositions to (Ti,Al) N-Mo2N. Measurements of the binding energy of Mo 3d photoelectrons in metallic Mo and the Mo2N nitride by X-ray photoelectron spectroscopy have shown that the transition from the former phase to the latter is accompanied by a negligible energy shift.