High temperature oxidation resistance of CrAlSiN coatings synthesized by a cathodic arc deposition process

The high-temperature oxidation behavior of the CrN and Cr-Al-Si-N coatings was studied. These coatings were deposited on silicon substrates by using a cathodic-arc deposition system with lateral rotating arc cathodes. Chromium and Al88Si12 cathodes were used for the deposition of Cr-Al-Si-N coatings. The deposited Cr0.38Al0.56Si0.06N exhibited higher hardness of 41 +/- 2 GPa and higher H-3/E*(2) ratio of 0.468 GPa than CrN due to the introduction of Al and Si to form a nanocrystalline structure. For the high-temperature oxidation test, the coated samples were annealed at 800 degrees C in air for 2 h. The Cr0.38Al0.56Si0.06N possessed much lower oxidation rate as measured by the oxide layer of the coatings. The addition of Al and Si in the coating may inhibit the formation of Cr2N phase and grain coarsening as found in the deposited CrN coating. In addition, the coexisting Al2O3 and SiO2 near the surface retarded the diffusion of oxygen into the Cr0.38Al0.56Si0.06N. The deposited Cr0.38Al0.56Si0.06N showed an oxidation behavior superior to the CrN. The high-temperature oxidation resistance of the CrN coatings can be improved by the formation of nanocomposite Cr-Al-Si-N. (C) 2007 Elsevier B.V. All rights reserved.