High-speed thermal imaging of yttria-stabilized zirconia droplet impinging on substrate in plasma spraying

The authors have developed an in situ monitoring system that captures the impacting phenomena of plasma-sprayed particles at 1×106frames∕s. The system clearly captured deformation and cooling processes of an yttria-stabilized zirconia droplet of 50μm in diameter impinging at 170m∕s on a smooth quartz glass substrate kept at room temperature. The images show that the liquid sheet jetting out sideways from the droplet detached from the substrate and kept on spreading without disintegration until its maximum extent. While the sheet was spreading, the center region of the flattened droplet cooled down much more rapidly.