Session BB1.2

9:00 AM BB1.2
DIAGNOSTICS OF IN-FLIGHT PARTICLES UNDER THERMAL SPRAYING CONDITIONS. Patrick Gougeon, Christian Moreau, Industrial Materials Institute, National Research Council Canada, Boucherville, Quebec, CANADA.

The National Research Council of Canada has developed an optical integrated system aiming at improving the control of thermal spray processes. To achieve this goal, this system measures the thermal radiation of the in-flight sprayed particles passing in front of an optical sensor head located near the spray jet. After transmission by optical fibers, the particle thermal radiation collected by the sensor head is measured by near infra-red photodetectors. The photodetector output signals are analyzed by a PC software for particle recognition and measurement of particle parameters. The parameters measurable by using the integrated optical system are the particle velocity, surface temperature, size and flux. In typical spraying conditions, the particle acquisition rate is higher than 50 part./sec. Depending on the optical system configuration, it is possible to measure particle velocities in the range of 30 - 1000 m/s. In this presentation, some examples will be given on the particle parameters measured during plasma, flame and HVOF spraying. The range of particle velocity and temperature reached in these processes are significantly different which leads to a corresponding adaptation of the diagnostic system. In particular, when achieving particle diagnostics under plasma spraying conditions, it can be necessary to use selective bandpass filters in front of the photodetectors. Using these filters permits to limit the influence of the intense radiation emitted by the plasma gas and the sprayed material vapors on the particle temperature measurement.