5.1 Manufacturers and users of alumina powders will find this test method useful to determine the particle size distribution of these materials for product specification, quality control, and research and development testing.1.1 This test method covers the determination of the particle size distribution of alumina in the range from 0.1 to 20 μm having a median particle diameter from 0.5 to 5.0 μm.1.2 The procedure described in this test method may be successfully applied to other ceramic powders in this general size range. It is the responsibility of the user to determine the applicability of this test method to other material.1.3 The values stated in SI units are to regarded as the standard. The values given in parentheses are for information only.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 It is important to recognize that the results obtained by this test method or any other method for particle size determination utilizing different physical principles may disagree. The results are strongly influenced by physical principles employed by each method of particle size analysis. The results of any particle sizing method should be used only in a relative sense and should not be regarded as absolute when comparing results obtained by other methods. Particularly for fine materials (that is, average particle size < 20 μm), significant differences are often observed for laser light scattering instruments of different manufacturers. These differences include lasers of different wavelengths, detector configuration, and the algorithms used to convert scattering to particle size distribution. Therefore, comparison of results from different instruments may be misleading.35.2 Light scattering theories (Fraunhofer Diffraction4 and Mie Scattering5) that are used for determination of particle size have been available for many years. Several manufacturers of testing equipment now have units based on these principles. Although each type of testing equipment utilizes the same basic principles for light scattering as a function of particle size, different assumptions pertinent to application of the theory and different models for converting light measurements to particle size, may lead to different results for each instrument. Furthermore, any particles which are outside the size measurement range of the instrument will be ignored, causing an increase in the reported percentages within the detectable range. A particle size distribution which ends abruptly at the detection limit of the instrument may indicate that particles outside the range are present. Therefore, use of this test method cannot guarantee directly comparable results from different types of instruments.5.3 This test method can be used to determine particle size distributions of catalysts, supports, and catalytic raw materials for specifications, manufacturing control, and research and development work.5.4 For fine materials (that is, average particle size < 20 μm), it is critical that Mie Scattering Theory be applied. This involves entering an “optical model” consisting of the “real” and “imaginary” refractive indices of the solid at the wavelength of the laser. The “imaginary” refractive index is also referred to as the “absorbance,” as it has a value of zero for transparent materials such as glass beads. For common materials and naturally occurring minerals (for example, kaolin), these values are known and published, and usually included in the manufacturer’s instrument manual (for example, as an appendix). For example, kaolinite measured at 589.3 nm has a “real” refractive index of 1.55. The absorbance (imaginary component) for minerals and metal oxides is normally taken as 0.001, 0.01 or 0.1. Many of the published values were measured at 589.3 nm (sodium light) but often values at other wavelengths are also given. Extrapolation, interpolation, or estimation to the wavelength of the laser being used can therefore be made.61.1 This test method covers the determination of the particle size distribution of catalyst, catalyst carrier, and catalytic raw material particles and is one of several found valuable for the measurement of particle size. The range of average particle sizes investigated was from 1 to 300 μm equivalent spherical diameter. The technique is capable of measuring particles above and below this range. The angle and intensity of laser light scattered by the particles are selectively measured to permit calculation of a volume distribution using light-scattering techniques.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 The technique of laser diffraction for particle size distribution analysis is extensively used in industry and academia both for on-line control and laboratory needs. Guidance is obviously useful in this regard.5.2 This guide can be used to develop methods of particle size analysis where well-established analysis procedures do not already exist. See Guide B821 for similar guidance and useful procedures for wet dispersion of metal powders and related compounds.1.1 This guide sets out the general approach to the particle size distribution measurement of powders, suspensions, or slurries using an appropriate wet or dry methodology by the laser diffraction technique. It is recommended for use in measurements of broad particle size distributions.1.2 The guide provides guidelines to the parameters that should be specified and a generalized guideline to reasonable and acceptable tolerances for points in the volume-based distribution curve such as x10 (Dv10), x50 (Dv50), x90 (Dv90), and D[4, 3] (volume moment mean). It is noted that ISO prefers the term x for particle size as opposed to other usage of d or D (implying diameter).1.3 This guide provides guidance on the verification of instrument performance in conjunction with the internal quality control (QC) audit functions of the instrument owner. Results should be reported in the format indicated by Practice E1617 and ISO 13320.1.4 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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