---
title: "ASTM C958"
url: "https://mat-cs.com/astm-c958/"
description: "This test method covers the determination of the particle size distribution of alumina or quartz powders in the range from 0.5 μm to 50 μm and having a median particle diameter from 2.5 μm to 10 μm using a sedimentation method."
---

ASTM Standard

# ASTM C958

Standard Test Method for Particle Size Distribution of Alumina or Quartz by X-Ray Monitoring of Gravity Sedimentation

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## Abstract

This test method details the standard procedures for the determination of the particle size distribution of alumina or quartz powders using X-ray monitoring of gravity sedimentation. This test procedure shall make use of an X-ray sedimentation apparatus, and ultrasonic probe or bath. An aqueous homogeneous dispersion of the specimen is permitted to settle in a cell. The decrease in particle concentration over a programmed settling distance is monitored by an X-ray beam passing through the sedimenting dispersion to a detector. The specimen concentration at any given sedimentation distance is inversely proportional to the X-ray flux and the equivalent diameter (spherical) is calculated from Stokes’ law.

## Scope

1.1 This test method covers the determination of the particle size distribution of alumina or quartz powders in the range from 0.5 μm to 50 μm and having a median particle diameter from 2.5 μm to 10 μm using a sedimentation method. This test method is one of several found valuable for the measurement of particle size. Instruments used for this test method employ a constant intensity X-ray beam that is passed through a sedimenting dispersion of particles.

1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.