Overview
EN ISO 19629:2022 (identical to ISO 19629:2018) specifies the flash method for determination of unidimensional thermal diffusivity of ceramic matrix composites with continuous fibre reinforcement. Published by CEN, the standard defines experimental conditions that ensure a unidimensional heat-transfer regime so the composite behaves effectively homogeneous along one symmetry axis. The method applies to materials stable during measurement over a wide temperature range (100 K to 2 800 K) and for thermal diffusivity values from 10−4 m²·s−1 to 10−7 m²·s−1.
Key topics and technical requirements
- Principle: A short, spatially uniform energy pulse (flash tube or pulse laser) is applied to the front face; the transient temperature rise on the back face is recorded and compared with a unidimensional analytical thermal model to obtain thermal diffusivity.
- Test specimens: Plane-parallel samples with thickness (h) defined in direction of heat transfer; testing is performed along one symmetry axis.
- Apparatus:
- Heat pulse source: flash lamp or pulse laser with uniform energy distribution.
- Test chamber: furnace, cryostat or draught-proof enclosure; furnace design requirements limit spatial gradients and drift.
- Detectors: thermocouples or optical pyrometers for absolute temperature; transient detectors (photodetectors or thermocouples) must detect changes ≥ 0.05 K and be linear for ΔT ≤ 5 K.
- Data acquisition and calibration: procedures to ensure timing accuracy and detector response are required.
- Environmental control: Tests can be run under vacuum (to reduce convection and oxidation) or gas; horizontal specimen orientation reduces convective effects.
- Measurement modelling: Use of the standard’s unidimensional analytical model (Annex A); other models must be documented in the test report.
- Reporting: Results, uncertainties, calibration, specimen preparation and any deviations from the standard model must be included.
Applications and users
EN ISO 19629 is essential for:
- Materials engineers characterizing thermophysical properties of advanced ceramics and ceramic composites.
- R&D teams developing high-performance ceramic-matrix composites for aerospace, power generation, thermal barrier coatings, and nuclear applications.
- Quality and test laboratories performing comparative thermal property measurements across temperatures.
- Designers and simulation engineers who require validated thermal diffusivity inputs for heat-transfer models.
Practical benefits include standardized, reproducible thermal diffusivity data used in thermal design, life prediction, and material selection for high-temperature components.
Related standards
- ISO 20507 - Fine ceramics vocabulary (terms and definitions).
- ISO 3611 - Dimensional measuring equipment (relevant for specimen dimensions).
- EN 60584-1 (IEC 60584‑1) - Thermocouples - reference tables (for temperature measurement).