Abstract
The effect of chamber pressure on the temperature and the velocity of the plasma sprayed particles was measured quantitatively through the chamber window. As the chamber pressure increases, the plasma flame shortens. At the same time, the particle slows down and the particle temperature increases. The multivariate analysis among the spray parameters and the measured values reveal that the particle temperature and the particle velocity can be controlled individually as a function of the chamber pressure and the spray distance. The zirconia coatings were fabricated by controlling the particle temperature and velocity at the impinging upon the substrate individually. Increase of the particle temperature increased the deposition efficiency, the density and the hardness of the coating. On the other hand, increase of the particle velocity up to a certain value also increased them, but the excessive velocity decreased them. Because the shortened dwelling time prevented the powder core from melting, even if the surface was sufficiently heated.
