ISO 19674:2025 PDF

Overview

ISO 19674:2025 specifies a test method for determining the internal (residual) stress in thin ceramic coatings by applying the Stoney formula to measured changes in the radius of curvature of isotropic strip or disc specimens with a single-face coating. The method is intended for fine (advanced) ceramics and requires well-characterized substrates, accurate measurement of coating and substrate thicknesses, and careful profile measurement before and after coating.

Key SEO phrases: ISO 19674:2025, fine ceramics, ceramic coatings, internal stress, Stoney formula, residual stress measurement, radius of curvature.

Key technical topics and requirements

• Principle: Internal stress is calculated from the coating-induced bending of a substrate using the Stoney formula. The technique assumes elastic deformation, spherical curvature and thin-film conditions.
• Specimen constraints:
  • Only isotropic substrates (scope limitation).
  • Strip specimens preferred; discs are acceptable.
  • Substrate must have uniform thickness and be stress-free prior to coating (anneal if necessary).
  • Coating thickness should be small compared with substrate thickness (document notes