Kohtaro Kuramitsu

The effect of powder feeding conditions on initial porosity in the interference region between two feeding points: feeding outlet diameter and height

Abstract A method for homogeneous powder packing into a cell is expected to be developed in both the fine ceramics and electronics industries. However, the method has not yet been developed sufficiently. In this paper, as a first step in the discussion of homogeneous powder packing, the powder porosity in the interference region between two feeding points into a cell is experimentally observed and analyzed by X-ray radiography. In particular, the effect of powder feeding height on the powder porosity in the interference region are noticed experimentally. The following conclusions are obtained. (1) For silica sand, the effect of powder feeding outlet diameter on the powder porosity in the interference region is seen to be larger than that of the powder feeding height. (2) However, for alumina powder, no effect of the powder feeding diameter and the powder feeding height on the powder porosity can be observed.

Measurement of initial porosity distribution in a powder cell by X-ray radiograph.

Homogeneous powder packing into a powder cell is one of the fundamental and also important problems which should be urgently elucidated in powder technology. For example, to get a sufficient mechanical strength of sintered powder chips in fine ceramics or electronics industry, a good homogeneous powder packing method should be developed. However, it has not been sufficiently established up to now.In this paper, from such a point of view, the initial powder packing states in different powder cells with one to five powder feeding points were systematically radiographed by X-ray, and their initial powder porosity (or powder bulk density) distributions were quantitatively analyzed by applying the analysis method presented by the authors. As the result, the following conclusions were obtained.(1) In every type of powder packing, the minimum porosity column was generated just under the powder feeding points.(2) The interference effect between two neighbouring powder feeding points changed remarkably depending upon test powder. That is, the porosity at the central region between two feeding points changed from the minimum value of the porosity distribution to the maximum one with the change of test powder.

On the One Dimensional Transmission Properties of the Bulk Density in Mobilized Particulate Materials inside an Inclined Tube

The behavior of particulate materials in general particulate processes can not be discussed without the consideration of dynamic factors. For example, if the discharge valve of a particulate hopper is opened, it will be observed that the discontinuity boundary of the bulk density is transfered upward in it storage. This phenomenon is expected to be solved as one of the most urgent problems for the establishment of the systematic design method of a discharge valve, but has not been elucidated yet. From this standpoint, in this paper, the transmission mechanism of the bulk density in mobilized particulate materials is fundamentally and experimentally discussed. As a result, it is pointed out that the bulk density in mobilized particulate materials has the property of a kinematic wave.