MICROSTRUCTURE-PROPERTY RELATIONSHIPS OF AIR PLASMA-SPRAYED TiO2 COATINGS
C.E.A. Le Ripault, B.P. 16, 37260 Monts, France
CEA/DAM Le Ripault, BP 16 - 37260 Monts - France
Plasma Technology Research Centre (CRTP), Department of Chemical Engineering University de Sherbrooke, Sherbrooke (Quebec) CANADA J1K 2R1
Maher I. Boulos
Department of Chemical Engineering University of Sherbrooke, 2500 Blvd. de lUniversite Sherbrooke J1К 2R1, PQ - Canada
ENSIL, ESTER Technopole, 87068 Limoges - France
Laboratoire Sciences des Procedes Ceramiques et de Traitements de Surface UMR CNRS 6638 University of Limoges 123 avenue Albert Thomas, 87060 LIMOGES - France
The electrical resistivity of titanium dioxide coatings produced by air plasma spraying has been investigated. It is well known that the quality and properties of plasma-sprayed coatings are strongly dependent on the in-flight particle characteristics. The spray parameters such as arc current intensity, total gas flow rate and powder size distribution were changed to understand the influence of these parameters on the particle characteristics before impact and consequently on the microstructure and electrical properties.
The particle states at impact were found to vary strongly with the particle size distribution as revealed by the in-flight characterizations. Small particles were shown to melt more completely in the plasma whereas coarse particles result in a poor microstructure because of the lowering in the particle melting extent. However, the particle parameters influence also the stoichiometry of the TiO2 coatings making difficult the direct correlation between the microstructure and electrical properties of titanium dioxide coatings.