音叉振動式粘度計を用いた粉体の見かけ粘度測定

Flowability is one of the important powder characteristics for control and/or estimation of behavior of powder flow in a process. In this study, we applied a relatively inexpensive viscosity measuring device for liquids, which is the tuning-fork vibration viscometer, to dry powders and tried to express the flowability of powder as an apparent viscosity. In order to apply the tuning-fork vibration viscometer to a dry powder, it is necessary to use a vertical vibration device and measure viscosities under various vertical vibration strengths. However, obtained results can be rearranged to the apparent viscosity under no-vibration by an interpolation or extrapolation. By the apparent viscosity and shear velocity calculated from the output of the viscometer enable to draw the pseudo-flow curve and pseudo-viscosity curve. Obtained apparent viscosities of tested powders can be expressed by an power function and indexes of viscosity can be defined.