Abstract

A two-wavelength particle imaging pyrometer has been developed to measure temperature, velocity and size of individual particles within a field of view and a depth of field that spans the entire particle stream in most thermal spray devices. The pyrometer provides continuous updates to particle condition profiles, histograms and correlations. The software locates particle streaks, determines the intensity ratio and dimensions of each streak, and calculates the particle temperature, velocity and size. Many forms of advanced materials processing technologies, such as thermal spray, spray-forming and atomization processes, have considerable need of process control sensor technology. These measurements provide the basis for application of the pyrometer to many of these processes. Particle temperature measurements of plasma-sprayed ceramic powder were obtained using a spectrometer and the pyrometer. Comparisons of the measurements show that the vision-based pyrometer has excellent accuracy. The standard deviation of the measurements was 40 K or about 1.3 %. Additional pyrometer measurements were used to determine its minimum detectable temperature and velocity change, which were 12.4 K and 2.77 m/s, or 0.4 % and 1.5 %, respectively. The vision-based particle sensor can now be applied to high performance control strategies to provide stable particle temperatures and velocities over long duration plasma spray processes.

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