Development of a new laser diffraction particle size distribution analyzer is discussed. One new feature is the laser source and the other is the light detection system. The laser employed is a short wave length violet laser, which improves the measuring ability down to ultra-fine particle region. The detection system adopting wide bore lens increases the measuring accuracy in fine particle range. The combination of the violet laser and the detection system makes the measuring range of the laser diffraction particle size analyzer wider.

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Hardness measurement of particulate matters has been carried out using the compression and stress relaxation test. In order to discuss the influence of particle size and particle shape, seven types of glass powder were used in the experiment. In this method, there was a region in which the applied pressure was linearly related to the displacement at the initial stage of compression. We applied Rumpf equation and Hertz equation to the proportional region and determined the constant k′ in Hertz equation. The constant k′ is independent of the particle size, showing that the hardness of particles can be reasonably evaluated by this method.

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Randomly packed bed of mono-sized spheres is generated by a computer simulation under the condition that a clearance between particle surfaces is larger than 0.4nm. The void fraction, the coordination number and the adhesion strength of packed bed are calculated from the simulation results and the correlations of these properties are investigated. As a result, the particle size significantly affects the coordination number as well as the void fraction. Since most of the powder bed properties depend on the interacting distance between particle surfaces, the coordination number has be varied depending on the powder bed properties.

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