ISO 18754:2020

Overview

ISO 18754:2020 specifies standardized laboratory methods for measuring density and apparent porosity of fine ceramics (advanced/technical ceramics), including ceramic matrix composites. The standard defines two measurement routes: Method A (liquid displacement / Archimedes' method) to determine bulk density, apparent solid density and apparent porosity, and Method B (geometric measurement) to determine bulk density from mass and linear dimensions.

Keywords: ISO 18754:2020, fine ceramics, density, apparent porosity, Archimedes' method, ceramic matrix composites.

Key Topics and Requirements

• Measured properties
  • Bulk density, apparent solid density, apparent porosity, geometric bulk density.
• Methods
  • Method A (liquid displacement / Archimedes')
    • Two impregnation options: boiling (Method A1 - e.g., boil for ≥3 h) or vacuum impregnation (Method A2 - evacuate to ≤2.5 kPa for 15 min, then introduce liquid and soak 30 min).
    • Limits: not appropriate for apparent porosity > 10 % (accuracy degrades); may be unreliable for open porosity < 0.5 %; not suitable for materials with average pore size > 600 µm.
    • Typical apparatus: drying oven (110 ± 5 °C), high-accuracy balance (0.1 mg for <10 g; 0.001 % for >10 g), thermometer, immersion liquid (distilled/de-ionized water or suitable organic liquid), suspending wire (≤0.25 mm), basket, beakers, vacuum/boiling equipment.
    • Drying to constant mass defined as two successive weights (after ≥2 h in oven) differing by ≤0.03 %.
  • Method B (geometric bulk density)
    • Bulk density from mass and measured linear dimensions; used when liquid immersion is unsuitable or when only bulk density is required.
• Specimen requirements
  • Minimum specimen volume: 0.1 cm3 per specimen. If smaller, provisions for multiple specimens (individual ≥0.04 cm3) or alternate methods are given.
  • Additional geometry requirements for ceramic matrix composites (e.g., minimum number of unit cells/plies) per the standard.

Applications and Users

• Intended for materials testing and quality control of advanced ceramics and ceramic matrix composites.
• Primary users:
  • Materials testing laboratories (including ISO/IEC 17025-accredited labs)
  • Ceramics manufacturers and R&D teams
  • Product engineers and quality assurance for components where density and porosity affect performance
• Practical uses: specification compliance, process control, material development, failure analysis and comparative characterization of advanced ceramic materials.

Related Standards

• ISO 386 (thermometers), ISO 758 (density of liquids), ISO 13385-1 (dimensional measuring equipment), ISO/IEC 17025 (laboratory competence), ISO 20507 (composite terminology).

This concise guide helps select the correct ISO 18754:2020 method and understand key constraints when measuring density and apparent porosity of fine ceramics.