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.