Osamu Hayakawa

Effect of particle shape on the particle size distribution measured with commercial equipment

Abstract The present paper describes the results of a round robin that has been performed to investigate the influence of particle shape on particle-size distributions measured with commercial particle-size analyzers. The commercial equipment based on the five kinds of measuring principle such as electrical sensing zone, laser diffraction and scattering, X-ray sedimentation, photosedimentation, and light-obscuration methods have been employed for analyzing blocky, flaky and rod-like ceramic particles. It is demonstrated that the particle shape has a strong influence on the particle-size distribution measured by the laser diffraction and scattering and by photosedimentation. The size range of rod-like particles is particularly wide when these methods are applied. It is also shown that the particle-size distributions of anisotropic samples measured by photosedimentation has a tendency to be remarkably scattered in the coarse-size range.

Experimental analysis of sample preparation conditions for particle size measurement

Abstract The influence of deagglomeration on an agglomerated sample, the dispersion media for a non-oxide sample, and the measuring conditions for a mixed sample on the particle size distribution are investigated in the present paper. It is found that deagglomeration is effective for dispersing an agglomerated powder well, regardless of the type and output power of the ultrasonic disrupters used. Ethanol is a useful dispersion medium for achieving stable measurements of non-oxide samples. In the measurement of a mixed sample, the measured distributions by X-ray sedimentation do not coincide with the distribution calculated from the weight ratio for each original sample. However, they coincide with the modified distribution from the X-ray absorption ratio for each original sample, because the cumulative mass % in this measuring principle is determined on the basis of the relationship between the X-ray transmittance ratio and the suspension concentration, depending on the sample materials.

Estimation of the optimum refractive index by the laser diffraction and scattering method: On the raw material of fine ceramics

Abstract In the field of ceramics, the particle size distribution of submicron powders has been measured by using many different types of equipment, which are based on different measuring principles. However, at present, the laser diffraction and scattering method is the most popular method in particle size analysis. Although this method is good for operation, the refractive index of the particles is required in order to calculate the size distribution. Proper results will not be obtained if the refractive index is not considered in the calculation. For the measurement of an unknown sample, this is the weakest point of the laser diffraction and scattering method. In this study, an estimation method of the optimum refractive index was established by simple data arrangement and the accuracy of the results was improved.