Norm

ASTM C1730 - 17 en

Standard Test Method for Particle Size Distribution of Advanced Ceramics by X-Ray Monitoring of Gravity Sedimentation

45,11 54,58 Incl BTW

Over deze norm

Status Definitief
Aantal pagina's 4
Gepubliceerd op 01-07-2017
Taal Engels

1.1 This 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.

1.1.1 However, 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:

Equation C1730-17_1

where:

D   =   the diameter of the largest particle expected to be present, in cm,
ρ   =   the particle density, in g/cm3,
ρ0   =   the suspending liquid density, in g/cm3,
g   =   the acceleration due to gravity, 981 cm/sec2, and
η   =   the suspending liquid viscosity, in poise.

1.1.2 A 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.

TABLE 1 Maximum Diameter of Ceramic Powders That Can Be Analyzed with Reynolds Number of 0.3 or Less in Water at 35 °C

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

0.29

Silicon Nitride

3.44

49.09

0.32

Yttrium Oxide

5.01

41.61

0.52

Zirconium Oxide

5.89

38.95

0.63

(A) A Reynolds number calculated for 50-µm particles sedimenting in water at 35 °C, with a density of 0.9941 g/cm3 and viscosity of 0.7225 cp. Entries with Reynolds numbers that exceed the recommended upper limit of 0.30 are included to indicate that samples of these materials containing 50-µm particles should not be analyzed using water as a dispersing liquid without addition of a viscosity modifier such as glycerol or sucrose.

1.2 The procedure described in this test method may be applied successfully to other ceramic powders in this general size range, provided that appropriate dispersion procedures are developed. It is the responsibility of the user to determine the applicability of this test method to other materials. Note however that some ceramics, such as boron carbide and boron nitride, may not absorb X-rays sufficiently to be characterized by this analysis method.

1.3 The values stated in cgs units are to be regarded as the standard, which is the long-standing industry practice. 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 and health practices and determine the applicability of regulatory limitations prior to use. Specific hazard information is given in Section 8.

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.

Details

ICS-code 81.060.30
Engelse titel Standard Test Method for Particle Size Distribution of Advanced Ceramics by X-Ray Monitoring of Gravity Sedimentation

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