prEN ISO 14705
(Main)Fine ceramics (advanced ceramics, advanced technical ceramics) - Test method for hardness of monolithic ceramics at room temperature (ISO/DIS 14705:2025)
Fine ceramics (advanced ceramics, advanced technical ceramics) - Test method for hardness of monolithic ceramics at room temperature (ISO/DIS 14705:2025)
ISO 14705:2016 specifies a test method for determining the Vickers and Knoop hardness of monolithic fine ceramics at room temperature.
Hochleistungskeramik - Prüfverfahren für die Härte von monolithischer Keramik bei Raumtemperatur (ISO/DIS 14705:2025)
Céramiques techniques - Méthode d'essai de dureté des céramiques monolithiques à température ambiante (ISO/DIS 14705:2025)
Le présent document spécifie une méthode d'essai pour déterminer la dureté Vickers et Knoop des céramiques techniques monolithiques à température ambiante.
Fina keramika (sodobna keramika, sodobna tehnična keramika) - Preskus trdote za monolitno keramiko pri sobni temperaturi (ISO/DIS 14705:2025)
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
01-november-2025
Fina keramika (sodobna keramika, sodobna tehnična keramika) - Preskus trdote za
monolitno keramiko pri sobni temperaturi (ISO/DIS 14705:2025)
Fine ceramics (advanced ceramics, advanced technical ceramics) - Test method for
hardness of monolithic ceramics at room temperature (ISO/DIS 14705:2025)
Hochleistungskeramik - Prüfverfahren für die Härte von monolithischer Keramik bei
Raumtemperatur (ISO/DIS 14705:2025)
Céramiques techniques - Méthode d'essai de dureté des céramiques monolithiques à
température ambiante (ISO/DIS 14705:2025)
Ta slovenski standard je istoveten z: prEN ISO 14705
ICS:
81.060.30 Sodobna keramika Advanced ceramics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
DRAFT
International
Standard
ISO/DIS 14705
ISO/TC 206
Fine ceramics (advanced ceramics,
Secretariat: JISC
advanced technical ceramics) —
Voting begins on:
Test method for hardness of
2025-09-08
monolithic ceramics at room
Voting terminates on:
temperature
2025-12-01
Céramiques techniques — Méthode d'essai de dureté des
céramiques monolithiques à température ambiante
ICS: 81.060.30
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
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Reference number
ISO/DIS 14705:2025(en)
DRAFT
ISO/DIS 14705:2025(en)
International
Standard
ISO/DIS 14705
ISO/TC 206
Fine ceramics (advanced ceramics,
Secretariat: JISC
advanced technical ceramics) —
Voting begins on:
Test method for hardness of
monolithic ceramics at room
Voting terminates on:
temperature
Céramiques techniques — Méthode d'essai de dureté des
céramiques monolithiques à température ambiante
ICS: 81.060.30
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2025
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
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STANDARDS MAY ON OCCASION HAVE TO
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Published in Switzerland Reference number
ISO/DIS 14705:2025(en)
ii
ISO/DIS 14705:2025(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Vickers hardness . 2
4.1 Principle .2
4.2 Symbols, abbreviated terms and designations .2
4.3 Significance and use .4
4.4 Apparatus .5
4.5 Test pieces .5
4.6 Procedure .5
4.7 Accuracy and uncertainties .8
4.8 Test report .8
5 Knoop hardness .12
5.1 Principle . 12
5.2 Symbols and designations . 12
5.3 Significance and use .14
5.4 Apparatus .14
5.5 Test pieces . . 15
5.6 Procedure . 15
5.7 Accuracy and uncertainty .16
5.8 Test report .17
Bibliography .21
iii
ISO/DIS 14705:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
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This document was prepared by Technical Committee ISO/TC 206, Fine ceramics.
This fourth edition cancels and replaces the third edition (ISO 14705:2016), which has been technically
revised.
The main changes are as follows:
— clarification of the required resolution of the diagonal measuring system (clauses 4.4.3 and 5.4.3)
— modification of the required measurement accuracy (clauses 4.6.12 and 5.6.12)
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
DRAFT International Standard ISO/DIS 14705:2025(en)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for hardness of monolithic ceramics
at room temperature
1 Scope
This document specifies a test method for determining the Vickers and Knoop hardness of monolithic fine
ceramics at room temperature.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 4545-1, Metallic materials — Knoop hardness test — Part 1: Test method
ISO 4545-2, Metallic materials — Knoop hardness test — Part 2: Verification and calibration of testing machines
ISO 4545-4, Metallic materials — Knoop hardness test — Part 4: Table of hardness values
ISO 6507-1, Metallic materials — Vickers hardness test — Part 1: Test method
ISO 6507-2, Metallic materials — Vickers hardness test — Part 2: Verification and calibration of testing machines
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
Vickers hardness
value obtained by dividing the applied force by the surface area of the indentation computed from the mean
of the measured diagonals of the indentations, assuming that the indentation is an imprint of the undeformed
indenter
Note 1 to entry: Vickers hardness may be expressed in two different units:
a) with unit GPa, obtained by dividing the applied force in N by the surface area of the indentation in mm ;
b) Vickers hardness number, obtained by dividing the applied force in kgf by the surface area of the indentation in mm .
3.2
Vickers indenter
indenter in the shape of a right-angle pyramid with a square base and an angle between opposite faces of 136°
Note 1 to entry: See Table 1 and Figure 1.
ISO/DIS 14705:2025(en)
3.3
Knoop hardness
value obtained by dividing the applied force by the projected area of the indentation computed from the
measurement of the long diagonal of the indentation, assuming that the indentation is an imprint of the
undeformed indenter
Note 1 to entry: The Knoop hardness may be expressed in two different units:
a) with units of GPa, obtained by dividing the applied force in N by the projected area of the indentation in mm ;
b) Knoop hardness number, obtained by dividing the applied force in kgf by the projected area of the indentation in
mm , without units specified.
3.4
Knoop indenter
indenter in the shape of a rhombic-based pyramid with the two angles between the opposite edges at 172,5°
and 130°
Note 1 to entry: See Table 3 and Figure 6.
4 Vickers hardness
4.1 Principle
Forcing a diamond indenter in the form of a right-angle pyramid with a square base, and with a specified
angle between opposite faces at the vertex into the surface of a test piece and measuring the length of the
diagonals of the indentation left in the surface after removal of the test force, F. See Figure 1 and Figure 2.
4.2 Symbols, abbreviated terms and designations
4.2.1 See Table 1, Figure 1 and Figure 2.
4.2.2 The Vickers hardness is denoted by the symbol HV, preceded by the hardness value and followed by
a number representing the test force (see Table 2).
Examples
a) Use of SI unit (GPa):
15,0 GPa HV 9,807 N represents a Vickers hardness of 15,0 GPa, determined with a test force of 9,807 N (1 kgf)
b) Use of the Vickers hardness number (no units specified):
1 500 HV 1 represents a Vickers hardness number of 1 500, determined with a test force of 9,807 N (1 kgf).
ISO/DIS 14705:2025(en)
Table 1 — Symbols, abbreviated terms and designations for Vickers hardness testing
Symbol or
abbreviated Designation
term
α Angle between the opposite faces at the vertex of the pyramidal indenter (136° ± 0,5°)
F Test force, in newtons
d Arithmetic mean, in millimetres, of the two diagonals, d and d
1 2
HV Vickers hardness
Test force
=×Constant
Surfaceareaofindentation
a) Units of GPa
136°
2Fsin
F
=0,001 =0,001 854
d d
b) Hardness number (no units specified)
136°
2Fsin
F
=0,102 =0,189 1
d d
c Arithmetic mean of the half of the two median crack lengths, 2c and 2c
1 2
SD Standard deviation
HV −HV
()
∑ n
=
n−1
where
HV
∑ n
HV
is the arithmetic mean of the Vickers hardness = ;
n
HV is the HV obtained from nth indentation;
n
n is the number of indentations.
NOTE Constant== =0,102 , where g is the acceleration due to gravity.
g 9,807
Table 2 — Hardness symbols and the nominal values of test forces, F, for Vickers hardness testing
Test force, F
Hardness symbol
(nominal value)
HV 0,5 4,903 N
HV 1 9,807 N
HV 2 19,61 N
HV 3 29,42 N
HV 5 49,03 N
HV 10 98,07 N
HV 20 196,1 N
ISO/DIS 14705:2025(en)
Figure 1 — Vickers indenter (diamond pyramid)
Figure 2 — Vickers indentation
4.3 Significance and use
Vickers indentation diagonal lengths are approximately 2,8 times shorter than the long diagonal of Knoop
indentations, and the indentation depth is approximately 1,5 times deeper than Knoop indentations made
at the same force. Vickers indentations are influenced less by the specimen surface flatness, parallelism of
the diamond axis to the test piece surface normal, and surface finish than Knoop indentations, but these
parameters should be considered, nonetheless. Vickers indentations are much more likely to cause cracks in
fine ceramics than Knoop indentations. Conversion between hardness scales shall not be made.
Vickers indentations on metallic materials are mainly formed by the plastic deformation. However, Vickers
indentations on fine ceramics are formed by micro-cracking and micro-fracture, besides plastic deformation.
This difference shall be noted for comparing the hardness of metals and ceramics.
ISO/DIS 14705:2025(en)
4.4 Apparatus
4.4.1 Testing machine, capable of applying a predetermined test force in the range of 4,903 N (0,5 kgf)
to 98,07 N (10 kgf), preferably 9,807 N (1 kgf), in accordance with ISO 6507-2. Verification of the test force
shall be carried out in accordance with ISO 6507-2.
4.4.2 Diamond indenter, in the shape of a right-angle pyramid with a square base, as specified in
ISO 6507-1 and ISO 6507-2. Verification of the indenter shall be carried out in accordance with ISO 6507-2.
4.4.3 Diagonal measuring system,
Magnifications should be provided so that the diagonal can be enlarged to greater than 25 % but less than
75 % of the maximum possible optical field of view as many objective lenses are nonlinear towards the edge
of the field of view.
The resolution required of the diagonal measuring system depends on the size of the smallest indentation
to be measured and shall be in accordance with Table 3. In determining the resolution of the measuring
system, the resolution of the microscope optics, the digital resolution of the measuring scale and the step-
size of any stage movement, where applicable, should be taken into account.
Table 3 — Resolution of the measuring system
Diagonal length, d
Resolution of the measuring sys-
Maximum permissible error
tem
mm
d < 0,050 0,000 25 mm 0,000 5 mm
0,050 ≤ d 0,5 % of d 1 % of d
A numerical aperture (NA) between 0,60 and 0,95 for the objective lens for the microscope is recommended.
NOTE The apparent length of a Vickers indentation increases as the resolving power and NA of a lens increases.
The range of NA specified by this test method corresponds to 40 to 100× objective lenses. The higher power lenses
may have higher resolution, but the contrast between the indentation tips and the polished surface may be less.
Verification of the measuring device shall be carried out in accordance with ISO 6507-2.
NOTE Indirect verification can be carried out by means of standardized blocks calibrated in accordance with
ISO 6507-3, following ISO 6507-2, or other approved and traceable ceramic standard reference blocks.
4.5 Test pieces
4.5.1 The test shall be carried out on a surface which is smooth, flat and free from foreign matter. The
test piece shall be polished to permit accurate measurement of the diagonal lengths of the indentation.
Preparation shall be carried out in such a way that any alteration of the surface hardness is minimized.
Surfaces shall not be thermally or chemically etched. If applicable, residual surface stresses shall be removed
by suitable polishing or annealing procedures.
4.5.2 The thickness of the test piece shall be at least 1,5 times the diagonal of the indentation, d, at least
2 times the crack length, c, and at least 0,5 mm, whichever is greater. No indentation damage shall be visible
at the back of the test piece upon completion of the test.
4.6 Procedure
4.6.1 In general, the test shall be carried out at room temperature within the limits of 10 °C to 35 °C. Tests
carried out under controlled conditions shall be made at a temperature of 23 °C ± 5 °C.
4.6.2 The test force shall be 9,807 N (1 kgf). In cases where significant chipping or lateral crack-spalling
occurs or where the impression is too faint, the test forces within the range 4,903 N (0,5 kgf) to 196,1 N
ISO/DIS 14705:2025(en)
(20 kgf), listed in Table 2, may be used. Other instances where a heavier load may be required are where the
grain structure is very coarse and the indentation area at lower loads may contact only a few grains of the
material (e.g. a multiphase material).
4.6.3 The following items shall be confirmed before the test.
a) Check the zero of the measuring system.
b) Check the measuring system using a calibrated scale or certified indentation in a test block.
c) Check the operation of the loading system by performing a test on a certified test block.
d) Check the condition of the indenter by examining the indentation made in the test block. Replace the
indenter, if necessary, by taking into account the conditions given in 4.6.10.
e) A test block with high hardness has to be used in order to obtain impressions in the same size range as
expected during tests on ceramics.
4.6.4 The indenter shall be cleaned prior to and during the test series, as ceramic powders or fragments
from the ceramic test piece can adhere to the diamond indenter.
4.6.5 The test piece shall be placed on a rigid support. The support surface shall be clean and free from
foreign matter. It is important that the test piece lies firmly on the support, so that displacement cannot
occur during the test.
4.6.6 Carefully adjust the illumination and focusing conditions, in order to obtain the optimum view and
clarity of the indentation. Both indentation tips shall be in focus at the same time. Do not change the focus
when measuring the distance from tip to tip.
4.6.7 Bring the indenter into contact with the test surface and apply the test force in a direction
perpendicular to the surface, without shock or vibration, until the applied force attains the specified value.
The time from the initial application of the force until the full test force is reached shall not be less than 1 s
nor greater than 5 s. The duration of application of the constant maximum test force shall be 15 s.
4.6.8 Throughout the test, the apparatus shall be protected from shock or vibration.
4.6.9 The distance between the centre of any indentations and the edge of the test piece shall be at least
2,5 times the mean diagonal of the indentation, and at least 5 times the mean length of the crack, as shown
in Figure 3. The distance between the centres of two adjacent indentations shall be at least 4 times the mean
diagonal of the indentation, and at least 5 times the mean length of the crack, as shown in Figure 3. If two
adjacent indentations differ in size and crack length, the spacing shall be based on the mean diagonal of the
larger indentation and the longer crack length.
ISO/DIS 14705:2025(en)
Key
1 edge of test piece
2 indentations
c length from the centre of indentation to the end of crack
d length of indent diagonal
l distance between centres of indentations
l ≥ 4d and 5c
l distance from centre of indentation to the edge of sample
l ≥ 2,5d and 5c
Figure 3 — Closest permitted spacing between indentations and from indentation to the test piece
edge for Vickers indentations
4.6.10 The satisfactory condition of the indenter shall be verified frequent
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