ACCURATE SUBMICRON PARTICLE-SIZE MEASUREMENT OF ALUMINA AND QUARTZ POWDERS USING A CUVETTE PHOTOCENTRIFUGE

An approach to improve the accuracy of submicron particle size distrib ution measurement using a cuvette photocentrifuge (Horiba CAPA-700) ha s been applied to a commercial alumina powder and a standard quartz po wder. This approach incorporates a correction for the light scattering from small particles, an improved raw data smoothing routine and a co rrection for the radial dilution effect. The results for the commercia l alumina powder show very good correspondence with the supplier's X-r ay sedimentometer data when corrected for light scattering and radial dilution; and allow a more complete data collection in the 0.3-0.03 mu m range. For the standard quartz powder (BCR 66) a less satisfactory r esult is found, with the light-scattering corrected data giving a much finer particle size distribution than expected for the standard powde r. Two possible reasons for this discrepancy, the nonsphericity of the quartz powder and an imaginary part of the refractive index of quartz due to impurities, are discussed along with the limitations of the ap proach for accurate submicron particle size measurement of polydispers ed irregularly shaped particles.