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AS 4784-2003


Sample preparation for particle size analysis — Dispersing procedures for powders in liquids

Sets out procedures for wetting a powder into a liquid, deagglomerating the wetted clumps, determining if solution composition can be adjusted to prevent reagglomeration, selecting dispersing agents to prevent reagglomeration and evaluating the stability of the dispersion against reagglomeration. This Standard is applicable to particles ranging in size from approximately 0.05 to 100 µm. This Standard is identical with and has been reproduced from ISO 14887:2000.
Published: 10/04/2003
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Table of contents
Cited references
Content history
Table of contents
About this publication
1 Scope
2 Normative reference
3 Terms and definitions
4 Symbols and abbreviated terms
5 Examination of the dry powder
5.1 Sampling
5.2 Clump size range and particle size range
5.3 Shape and surface roughness; their variation with size
6 Selection of a liquid and trial dispersion
6.1 Selection of a liquid
6.2 Preparation of a test paste of the powder
6.3 Preparation of a dilute dispersion of the powder
7 Examination of the dispersion
7.1 Evaluate for under- or over-grinding
7.2 Evaluation of stability
7.2.1 Introduction
7.2.2 Notes on optical microscopy
7.2.3 Notes on electron microscopy
7.3 Evaluation of any flocs formed
8 Identification of possible dispersing agents
8.1 Wetting of the solid particle by the liquid
8.2 General principles
8.3 Charge stabilization
8.3.1 Introduction
8.3.2 Surface ionization
8.3.3 Differential dissolution of lattice ions
8.3.4 Adsorption of multiply charged ions
8.3.5 Adsorption of surfactant ions
8.4 Steric stabilization
8.5 Procedure for selection
8.5.1 Determination of the powder's category
8.5.2 Determination of the liquid's category
8.5.3 Determination of the category of a prospective dispersing agent
8.5.4 Identification of commercial sources of dispersing agents
9 Optimization of the dispersion method
9.1 Introduction
9.2 Comparison of the effectiveness of possible dispersing agents
9.3 Optimization of the method of breaking up clumps
9.3.1 Notes on ultrasonic treatment
9.3.2 Management of heat buildup during clump breakup
9.3.3 Determination of the optimum range for clump breakup energy
9.3.4 Documentation of the optimum breakup conditions
9.4 Determination of the optimum quantities to use
10 Maintenance of dispersion stability during sample handling
10.1 Stability during dilution
10.2 Stability during change in pH
Annex A
A.1 Sedimentation behaviour
A.2 Surface-charge density
A.3 Rheology
A.4 Attenuation of sound or electrical pulses
Annex B
Cited references in this standard
Content history
DR 02330
AS 4784-2003 Rec:2016