High Temperature Material Processes (An International Quarterly of High-Technology Plasma Processes) An International Journal

ISSN for PRINT: 1093-3611

For Online Access

Best Paper Award Selection - Editorial Board Site

2000, Volume4

Issue 3

152 pages

Issue price - $144.00

Reidar Haugsrud
Centre for Materials Science Gaustadalleen 21,N-0371 Oslo, Norway

Ingard Kvernes
Kvernes Technology AS., Munkedamsveien 96,P-box 2806 Solli, N-0204 Oslo, Norway

Erick Lugscheider
Werkstoffwissenschaften Lehr und Forschungsgebeit der RWTH Jiilicher Sir. 342-352 52070 Aachen; Surface Engineering Institute (IOT), RWTH University of Technology Aachen, Augustinerbach 4-22, 52066 Aachen, Germany

Specimens of air plasma sprayed thermal barrier coatings with a Ni-23Co-17Cr-12Al-0.5Y bond coat have been oxidised in air at 900°C for 300-3000 hours. The oxide scale formed between the ceramic and the bond coat consists of essentially pure AI₂O₃, except at the interface with the ceramic overlay, where the composition of the oxide reflects that of the bond coat. The oxidation rate decreases with time and reflects growth of AI₂O₃, through inward grain boundary diffusion of oxygen. An inter-metallic phase identified as NiAl, precipitated during high temperature exposure. The thickness of the inter-metallic zone decreased with increasing oxidation duration. This was interpreted to reflect diffusion of Al toward the oxide and into the substrate. The amount of transient oxides at the surface was found to depend on the surface topography.

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