Overview
EN ISO 14705:2021 (identical to ISO 14705:2016) defines a standardized test method for determining Vickers and Knoop hardness of monolithic fine ceramics (advanced/technical ceramics) at room temperature. Published by CEN as a European adoption of the ISO document, it is the reference for hardness measurement practice, reporting and uncertainty evaluation for ceramic materials.
Key topics and technical requirements
- Scope: Procedures for measuring Vickers hardness (HV) and Knoop hardness on monolithic ceramics at ambient temperature.
- Test principles:
- Vickers: diamond right‑angle pyramid indenter (face angle 136° ± 0.5°); hardness derived from mean diagonal length of the square imprint.
- Knoop: rhombic‑based pyramid indenter (angles 172.5° and 130°); hardness based on projected area from the long diagonal.
- Units and notation: hardness may be reported in GPa or as hardness numbers (e.g., 1 500 HV 1); test force is appended (e.g., HV 10 for 98.07 N).
- Nominal Vickers test forces (examples from the standard):
- HV 0.5 = 4.903 N
- HV 1 = 9.807 N
- HV 10 = 98.07 N
- Apparatus & calibration: machine capability, indenter geometry and verification (references to ISO 6507 and ISO 4545 series for calibration and verification).
- Test pieces & preparation: surface finish, flatness and orientation requirements to reduce measurement artefacts.
- Procedure: loading, dwell time, measurement of indent diagonals (Vickers) or long diagonal (Knoop), number of indentations and location.
- Accuracy & uncertainty: statistical treatment, standard deviation, and reporting requirements.
- Special notes:
- Vickers indentations in ceramics often involve micro‑cracking and micro‑fracture, not just plastic deformation.
- Do not convert indiscriminately between hardness scales.
Applications and who uses it
EN ISO 14705:2021 is used by:
- Materials testing and metallurgical/ceramics laboratories for quality control and batch acceptance.
- R&D teams developing advanced ceramics (structural ceramics, electrical ceramics, wear-resistant components).
- Process engineers monitoring sintering, densification and surface treatments.
- Failure analysts evaluating fracture‑related hardness effects.
- Procurement and certification bodies requiring standardized hardness data for specifications.
Typical applications include material selection, comparative property databases, coating/substrate hardness checks, and validating production processes for monolithic ceramic components.
Related standards
- ISO 6507 series (Vickers hardness test - method and machine verification)
- ISO 4545 series (Knoop hardness test - method and verification)
- Adopted as EN ISO 14705:2021 by CEN for harmonized European use
Keywords: EN ISO 14705:2021, ISO 14705:2016, fine ceramics, advanced ceramics, Vickers hardness, Knoop hardness, monolithic ceramics, hardness test, room temperature.
