High-rate low-temperature PVD of thick 10 μm α-alumina coatings

Abstract

α-Al2O3 coatings have been deposited by evaporation of Al in an anodic arc with a growth rate of ∼ 5 μm•h-1 at 640?C under the conditions of low ionization of the Al vapors and an increased concentration of atomic oxygen, which has been achieved by the use of a hollow anode.Intensive (current density up to 15 mA•cm-2) low-energy (50 eV) ion bombardment has provided deposition of adhesive single-phase nanocrystalline (50-150 nm) α-Al2O3 coatings with a thickness of up to 10 μm with low intrinsic stresses (1.5 GPa) and low microstrains of the crystal lattice (less than 0.1%). The composition of the discharge plasma has been determined using the optical spectroscopy method. The effect of the O2 flow and the hollow anode current on the growth rate of the alumina coatings has been investigated and it has been shown that the increasing degree of O2 dissociation promotes an increase in the growth rate of coatings. © 2019 IOP Publishing Ltd. All rights reserved.