Gaseous fluidization of short fibers and SiC powders, influence of temperature and pressure
Abstract
The fluidization of short Hi Nicalon S fibers was investigated before considering CVD coatings with controlled composition and thicknesses. The fluidization of a short fiber batch alone being delicate and not reproducible, the study consisted in comparing the hydrodynamic behavior of a powder alone, to that of a short fiber/powder mixture. The fluidization behavior of the particle beds was studied by following their pressure drop as a function
of pressure and temperature. The minimum fluidization velocity (U$_{mf}$) was evaluated at room temperature (T$_{amb}$) at different reduced pressures, and at 200 mbar as a function of temperature. The results are in good agreement with the theoretical equations. At low pressures and T$_{amb}$, U$_{mf}$ increases rapidly. In contrast, U$_{mf}$ varies only slightly with temperature. While the pressure does not seem to affect the fluidization behavior of the powder alone, it displays a clear optimum at 200 mbar for the short fiber/powder mixture.
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