ISO 10070:2019

Overview

ISO 10070:2019 specifies a laboratory method to determine the envelope-specific surface area of metallic powders from measurements of the permeability to air of a packed powder bed under steady‑state (constant pressure drop) laminar flow conditions near atmospheric pressure. The standard applies to metallic powders (including hardmetal powders) up to 1 000 µm in diameter, though it is typically used for particles between 0.2 µm and 75.0 µm. ISO 10070:2019 is device‑agnostic - it describes principles, calculations and general procedure and includes an informative annex (Annex A) with practical examples of specific test methods (Lea & Nurse, Zhang Ruifu, Gooden & Smith).

Key topics and technical requirements

• Permeametry principle: Measure volume flow rate and pressure drop of dry air across a packed powder bed and calculate permeability using Darcy’s law.
• Surface area derivation: Convert permeability and permeable porosity into an envelope‑specific surface area using the Kozeny‑Carman relation and the Carman‑Arnell modification (accounts for slip flow).
• When to use which formula: Use the Carman‑Arnell formulation when volume‑specific surface area is > 10 m‑1 (mean particle size < ~6 µm) because slip flow becomes significant; Kozeny‑Carman may be used for coarser powders by agreement.
• Test conditions: Steady‑state laminar flow, air at near atmospheric pressure; constant volume (variable pressure) methods are excluded.
• Scope limits: Not intended for non‑equiaxial particles (flakes, fibres) unless agreed; not applicable to powder mixtures, powders containing binders or lubricants; agglomeration affects results and de‑agglomeration procedures (Annex B) must be agreed between parties.
• Device flexibility: The standard does not mandate commercial equipment; Annex A gives examples of lab-built and commercial devices for guidance.
• Reporting: Requires reporting of permeability, porosity, test parameters and converted equivalent sphere diameter when relevant.

Applications and users

ISO 10070:2019 is used by:

• Powder manufacturers and suppliers for quality control and specification of metallic powders
• Powder metallurgy and additive manufacturing R&D teams evaluating particle characteristics
• QC/analytical laboratories performing surface area and porosity testing
• Instrument and test‑equipment manufacturers validating permeametry devices Practical uses include characterizing powders for sintering, compaction, flowability assessments, and converting permeability data into envelope‑surface metrics used in process control and material specifications.

Related standards

• ISO 3954 (Powders for powder metallurgical purposes - Sampling) is referenced as a normative document.
  Note: Envelope‑specific surface area from permeametry differs from total surface area measured by gas adsorption methods; the two are complementary for powder characterization.

Keywords: ISO 10070, metallic powders, envelope-specific surface area, permeability to air, powder bed, permeametry, Kozeny‑Carman, Carman‑Arnell, porosity, powder metallurgy.