Ion-Assisted α-Al2O3 Coating Deposition by Anodic Arc Evaporation at 500–550°С

The paper studies the α-phase formation and structure of Al2O3 coatings deposited by the anodic arc evaporation in the low temperature range of 500–550°С. The current density of the ion assistance is varied up to 20 mA/cm2 and the ion energy ranges between 25–150 eV. The coating deposition rate is constant and equals 3 μm/h. The X-ray diffraction and infrared analyses are used to investigate the phase composition of the Al2O3 coating. It is found that the α-phase formation occurs at a 75–100 V bias voltage threshold, and the α-phase is stable within the limited range of the ion energy. The growth in the ion energy leads to the size reduction of the α-phase nanocrystallites and the coating amorphization. The coating structure is characterized by the crystallographic texture (300), which probably dominates due to the α-phase formation at the orientation ratio (440)γ-Al2O3/(300)α-Al2O3.