Abstract
Physical, mechanical, and electrical properties of flame-sprayed barium titanate coatings were considerably affected by heat treatment.
Micro-crystallites were developed with the elevation of annealing temperature. The structure of crystallites changed to tetragonal system at 1, 400°C. The effects of the substrate on the crystallites structure was remarkable in rod sprayed coatings. The structure of the coatings with substrate annealed at 1, 400°C turned into tetragonal system, whereas in case of the structure without the substrate annealed at that temperature still remained in cubic system.
The bond strength increased with the elevation of annealing temperature up to 1, 200°C.
The surface roughness after heat treatment reached its maximum at 1, 400°C. The dielectric constant and dissipation factor proportionally increased with the elevation of annealing temperature. Furthermore, the dependence of properties on the temperature more increased at higher annealing temperature.
The breadth of the peak of Curie point increased as compared with that of ceramic barium titanate when heat treated at above 1, 200°C (in rod-spraying) or above 1, 000°C (in powder-spraying).
When the annealing temperature was higher, the insulation resistance was lower; however, the dependence of the resistance on the temperature was less.
