PHASE FORMATION CONTROL IN PLASMA SPRAYED ALUMINA-CHROMIA COATINGS

Alumina is an inexpensive material often used as feedstock for plasma spraying. Hard corundum (alpha-Al2O3) is desirable in coatings, but other phases, unstable at elevated temperatures, also form as a result of the complexity of the spraying processes. When chromia (Cr2O3) is added to Al2O3, a comp...

Full description

Saved in:
Bibliographic Details
Published in:Ceramics (Praha) 2011-01, Vol.55 (3), p.294-300
Main Authors: Dubsky, J, Chraska, P, Kolman, B, Stahr, C C, Berger, L-M
Format: Article
Language:English
Subjects:
Alumina
Aluminum oxide
Chromia
Chromium oxides
Coatings
Corundum
Deposition
Feedstock
Phase stabilization
Plasma spraying
Spraying
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Alumina is an inexpensive material often used as feedstock for plasma spraying. Hard corundum (alpha-Al2O3) is desirable in coatings, but other phases, unstable at elevated temperatures, also form as a result of the complexity of the spraying processes. When chromia (Cr2O3) is added to Al2O3, a complex corundum type alpha-(Al,Cr)2O3 phase forms in the deposits. Two types of Al2O3/Cr2O3 powder feedstock with 2, 8, 33 and 50% Cr2O3 were sprayed: fused materials and mixtures of Al2O3 and Cr2O3 powders. Coatings were made either by using the water-stabilised plasma (WSP) system or commercial atmospheric plasma spraying (APS) and compared using XRD, SEM and microanalysis. Coatings made from fused feedstock by both spraying methods contain the corundum phase with its fraction increasing with increasing Cr2O3 content. In case of mixed feedstock, the stabilisation effect was observed for WSP spraying only. An explanation of this finding is offered on the basis of differences in the spraying technologies, in particular the spraying temperature.
ISSN:0862-5468
1804-5847