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ASTM International , 07/01/2017
Publisher: ASTM
File Format: PDF
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1.1This test method covers the determination of particle size distribution of advanced ceramic powders. Experience has shown that this test method is satisfactory for the analysis of silicon carbide, silicon nitride, and zirconium oxide in the size range of 0.1 up to 50 µm.
1.1.1However, the relationship between size and sedimentation velocity used in this test method assumes that particles sediment within the laminar flow regime. It is generally accepted that particles sedimenting with a Reynolds number of 0.3 or less will do so under conditions of laminar flow with negligible error. Particle size distribution analysis for particles settling with a larger Reynolds number may be incorrect due to turbulent flow. Some materials covered by this test method may settle in water with a Reynolds number greater than 0.3 if large particles are present. The user of this test method should calculate the Reynolds number of the largest particle expected to be present in order to judge the quality of obtained results. Reynolds number (Re) can be calculated using the following equation:
1.1.2A table of the largest particles that can be analyzed with a suggested maximum Reynolds number of 0.3 or less in water at 35°C is given for a number of materials in Table 1. A column of the Reynolds number calculated for a 50-µm particle sedimenting in the same liquid system is also given for each material. Larger particles can be analyzed in dispersing media with viscosities greater than that for water. Aqueous solutions of glycerine or sucrose have such higher viscosities.
Particle Composition
Particle Density
Maximum Particle Diameter, µm
Reynolds Number for 50 µmA
Aluminum Nitride
3.26
50.36
0.29
Aluminum Oxide
3.965
46.01
0.39
Cerium Dioxide
7.132
36.13
0.80
Silicon Carbide
3.217
50.68
Silicon Nitride
3.44
49.09
0.32
Yttrium Oxide
5.01
41.61
0.52
Zirconium Oxide
5.89
38.95
0.63
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