ISO 3923-2:1981

Overview

ISO 3923-2:1981 defines the Scott volumeter method for determining the apparent density of metallic powders. This standard is essential for powders that do not flow freely through a 5 mm orifice, making traditional funnel methods inadequate. Unlike the oscillating funnel method (ISO 3923-3), which offers higher precision, the Scott volumeter method is preferred when vibration could alter powder properties during testing.

This International Standard specifies the principle, symbols, apparatus, sampling, procedure, expression of results, and reporting requirements. It is crucial for consistent and reliable measurement of apparent density in metallurgical and powder metallurgy applications.

Key Topics

• Scope and Applicability
  Applicable to metallic powders that are not free flowing through a 5 mm orifice. The Scott volumeter method avoids vibration-induced powder property changes.

• Apparatus Components

  • Scott volumeter comprising:
    • A two-section funnel with a brass sieve (1.8 mm aperture)
    • A baffle box with glass baffles to reduce powder velocity and ensure even filling
    • A vibration-free stand and base to hold the apparatus
  • Cylindrical cup with a fixed volume (25 ± 0.05 cm³) and polished interior
  • Precision balance with ± 0.05 g accuracy

• Principle and Measurement
  The measured mass of powder filling a cup with a known volume in a loose and uncompressed state represents the apparent density (g/cm³). Powder is cascaded through the apparatus to fill the cup, ensuring accuracy and reproducibility.

• Sampling and Preparation
  Testing is performed on at least 100 cm³ samples, usually in the as-received condition. Drying is permitted under vacuum or inert gas if the powder is oxidation-sensitive, but not if volatiles are present.

• Procedure Summary

  1. Pour powder into the Scott volumeter funnel until the cup is filled and powder overflows.
  2. Aid passage through sieve with light brushing if necessary.
  3. Level powder carefully without compressing or vibrating.
  4. Tap cup lightly to settle powder without spilling.
  5. Weigh powder to nearest 0.05 g.
  6. Perform three replicate measurements and report the average apparent density along with highest and lowest values if variance exceeds 1%.

• Test Reporting
  Include identification details of the sample, reference to ISO 3923-2, drying or sample preparation details, test results, any deviations or optional procedures performed, and remarks on any unusual occurrences impacting results.

Applications

• Powder Metallurgy
  Ensures accurate density data for powders used in sintering, pressing, and additive manufacturing processes.

• Quality Control
  Enables manufacturers to verify powder consistency and compliance with material specifications.

• Research and Development
  Supports material scientists in characterizing metallic powders and developing new alloys or powder formulations.

• Materials Handling
  Helps optimize storage, transport, and processing of non-free-flowing metallic powders by providing reliable physical property data.

Related Standards

• ISO 3923-1: Metallic powders - Apparent density - Funnel method
  For powders that flow freely through a 5 mm orifice, using a simple funnel measurement.

• ISO 3923-3: Metallic powders - Apparent density - Oscillating funnel method
  Offers better precision for powders sensitive to vibration, but not suitable when vibration must be avoided.

• Additional Powder Metallurgy Standards
  Standards on sampling, particle size analysis, and flowability support comprehensive powder characterization.

By adhering to ISO 3923-2:1981, industries and laboratories guarantee accurate, reproducible apparent density measurements of metallic powders that resist free flow. This supports robust quality assurance, process optimization, and innovation in powder metallurgy and related fields.