OXIDATION IMPROVEMENT OF TI-48AL-2CR-2NB INTERMETALLICS BY AIR PLASMA-SPRAYED ZRO2-NI-4.5WT.PERCENT-AL COATINGS

Authors
Citation
Ic. Hsu et Sk. Wu, OXIDATION IMPROVEMENT OF TI-48AL-2CR-2NB INTERMETALLICS BY AIR PLASMA-SPRAYED ZRO2-NI-4.5WT.PERCENT-AL COATINGS, Surface & coatings technology, 90(1-2), 1997, pp. 6-13
Citations number
18
Categorie Soggetti
Materials Science, Coatings & Films
ISSN journal
02578972
Volume
90
Issue
1-2
Year of publication
1997
Pages
6 - 13
Database
ISI
SICI code
0257-8972(1997)90:1-2<6:OIOTIB>2.0.ZU;2-G
Abstract
The air plasma spraying (APS) technique was employed to modify the oxi dation resistance of Ti-48Al-2Cr-2Nb intermetallics. The Ni-4.5wt.%Al bond-coat provided a good bonding strength between matrix and thermal barrier top-coat. Static and thermal cyclic tests showed improvement i n oxidation resistance of APS-coated Ti-48Al-2Cr-2Nb alloy although th e oxidation kinetics did not obey the parabolic law. The oxidation rat e was reduced by the formation of NiO scale on the outer layer of the bond-coat which slowed down the oxygen permeation. Tt was healed by th e formation of an Al2O3 layer in the inner layer of the bond-coat whic h can prevented outward diffusion of titanium. A Ti-AI-Ni inter-diffus ional layer was observed in between the bond-coat and the matrix. A me chanism of oxidation protection by APS coatings is therefore proposed in this study.