Al2O3 thin films deposition by reactive evaporation of Al in anodic arc with high levels of metal ionization

• Published in: Surface & coatings technology Vol. 359; pp. 117 - 124
• Main Authors: Gavrilov, N.V., Kamenetskikh, A.S., Trernikov, P.V., Emlin, D.R., Chukin, A.V., Surkov, Yu.S.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.02.2019; Elsevier BV
• Subjects: Al2O3 coating; Aluminum oxide; Anodes; Arc deposition; Coatings; Crucibles; Crystallites; Evaporation; Gas mixtures; Hollow cathodes; Ion assistance; Ion current density; Ion currents; Ionization; Magnetic fields; Metal vapors; Plasma arc heating; Reactive thermal evaporation; Solenoids; Thin films; α-Al2O3; Al2O3 coating; Reactive thermal evaporation; Ion assistance; α-Al2O3
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2018.12.065

The results of studying the parameters of the plasma generated in an arc with a self-heating hollow cathode and a vaporizable anode placed in a magnetic field of two oppositely connected solenoids are presented. Compression of the discharge column in an inhomogeneous magnetic field provides an increase in power density on the surface of the crucible anode to ~1 kW/cm2 and an increase in the degree of ionization of the metal vapor to 50–80%. Using the method of reactive evaporation of aluminum in the Ar/О2 gas mixture we obtained Al2O3 coatings at the rate of 4–8 μm/h under an ion current density of 6–11 mA/cm2, a bias voltage of 50–200 V, and a temperature of 620 °С. It is shown that, with an increase in the ion current density and ion energy, the fraction of the α-phase in the Al2O3 coating increases to 100%. The single-phase α-Al2O3 coatings are characterized by the predominant orientation of crystallites (300). •Nanocrystalline Al2O3 coatings deposited at 620 °C by reactive anodic thermal evaporation of Al•High deposition rate (8 μm/h) and Al ionization degree (0.8) achieved by discharge compression in magnetic field•α-Al2O3 content grows up to 100% with increasing of intensity of ion assistance.•Crystallization mechanism of α-Al2O3 depends on composition of accelerating ions on coating surface.•Domination of Al ion leads to γ-phase grow and following γ-α recrystallization under ion bombardment.