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The authors have developed an in situ monitoring system for particle impacts under atmospheric dc plasma spraying conditions. This system utilized a high-speed video camera coupled with a long-distance microscope, and was capable of capturing the particle-impinging phenomena at one million frames per second. To understand the coating formation mechanism, two approaches were attempted, i.e., observation of the single splat formation and the subsequent coating formation. In the former case, the deformation and cooling processes of yttria-stabilized zirconia (YSZ) droplets impinging on substrates were successfully captured. In the latter case, multiple-droplet-impacting phenomena were observed as an ensemble treatment. Representing the coating process, the tower formation (0-dimensional) and bead formation (1-dimensional) were observed under typical plasma spray conditions for thermal barrier coatings using a triggering system coupled with the motion of a robot. The obtained images clearly showed the coating formation resulting from the integration of single splats. [ABSTRACT FROM AUTHOR]

An image sensor for a video camera of 1 000 000 frames per second (fps) was developed. The specifications of the developed sensor are as follows: 1) frame rate: 1 000 000 fps; 2) pixel count: 81 120 (= 312 × 260) pixels; 3) total number of successive frames: 103 frames; 4) gray levels: 10 b; and 5) open area of each pixel (fill factor): 580 square micrometers (13%). The overwriting function is installed for synchronization of image capturing with occurrence of the target event. Sensitivity is significantly high with the large photogate. Some innovative technologies were introduced to achieve ultrahigh performance, including slanted linear CCD in situ storage, curving design procedure, and a CCD switch with fewer metal shunting wires. They are applicable to the development of other new high-performance image sensors. [ABSTRACT FROM AUTHOR]