Title

Al-O-N Based Duplex Coating System For Improved Oxidation Resistance Of Superalloys And Nicraly Coatings

Keywords

Coatings; Oxidation; Photostimulate luminescence; Residual stress; Thermally grown oxide

Abstract

Performance of an Al-O-N based duplex coating system (DCS) was examined in order to improve the high-temperature oxidation resistance of superalloys and the low-pressure plasma sprayed NiCrAlY coatings. The DCS (∼5 μm thick) was deposited using pulsed DC reactive magnetron sputtering as an external coating on Rene'N5 superalloy with and without NiCrAlY coating. DCS coatings were characterized using photo-stimulated luminescence spectroscopy, optical microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy before and after high-temperature oxidation. As-deposited DCS contained varying amounts of α-, γ-Al2O3 and amorphous phases depending on the chemistry and surface characteristics of the substrate. Heat treatment at 1121 °C (2050 °F) for 2 h in air facilitated complete phase transformation to equilibrium α-Al2O3 in the DCS. Improvement in oxidation resistance was observed for DCS specimens during 250-h oxidation at 1121 °C (2050 °F). In particular, DCS was found to be very effective as an external coating on the rough (as-sprayed) NiCrAlY surface. The superior oxidation resistance of the specimens with DCS may be attributed to the formation of slow-growing and adherent alumina scale and the prevention of Ni/Cr-rich oxide formation. © 2003 Elsevier B.V. All rights reserved.

Publication Date

5-24-2004

Publication Title

Surface and Coatings Technology

Volume

183

Issue

2-3

Number of Pages

224-232

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/j.surfcoat.2003.09.044

Socpus ID

2442461052 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/2442461052

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