Nanocrystalline gamma alumina coatings by inverted cylindrical magnetron sputtering

• Published in: Surface & coatings technology Vol. 201; no. 1; pp. 168 - 173
• Main Authors: Khanna, Atul, Bhat, Deepak G.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 12.09.2006; Elsevier
• Subjects: AC sputtering; Alumina coatings; Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Inverted cylindrical magnetrons; Materials science; Metals. Metallurgy; Nonmetallic coatings; Other topics in materials science; Physics; Production techniques; Surface treatment; Inverted cylindrical magnetrons; Alumina coatings; AC sputtering; Magnetrons; Physical vapor deposition; Surface treatments; Non metal coating; Alumina; Nanocrystal; Sputtering
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2005.11.109

Alumina coatings were deposited on glass, silicon and stainless steel substrates by magnetron sputtering of two cylindrical aluminum targets in argon–oxygen plasma using a mid frequency AC power supply operated at 41 kHz and 5 kW. No substrate heating was used during the deposition process. Reactive sputtering was carried out in the poisoned mode of the targets at low deposition rates of about 0.09 nm s − 1 . The coatings were characterized by X-ray diffraction studies and found to be nano-crystalline, γ-phase of aluminum oxide. The coatings thickness was measured using the optical interference effects in the UV–visible spectrum of thin films deposited on glass substrates. Thin film thickness after 4 h of reactive sputtering was found to be 1.3 μm. We further studied the oxidation resistance of the alumina coatings produced on stainless steel substrates at a temperature of 400 °C. Coatings were found to be completely stable at this temperature and prevented the oxidation of underlying stainless steel substrate.