ISO 14704:2016
(Main)Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for flexural strength of monolithic ceramics at room temperature
Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for flexural strength of monolithic ceramics at room temperature
ISO 14704:2016 specifies a test method for determining the flexural strength of monolithic fine ceramics, and whisker- or particulate-reinforced ceramic composites, at room temperature and applies to materials with grain size less than 200 µm. This test method may be used for materials development, quality control, characterization and design data-generation purposes. NOTE Since fracture is due to tensile stress, flexural strength data can be used to calculate a uniaxial tensile strength considering the effect of the tested volume and Weibull-statistics. So, flexural strength is often used in substitute for uniaxial tensile strength.
Céramiques techniques — Méthode d'essai de résistance en flexion des céramiques monolithiques à température ambiante
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INTERNATIONAL ISO
STANDARD 14704
Third edition
2016-04-15
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Test method for flexural strength
of monolithic ceramics at room
temperature
Céramiques techniques — Méthode d’essai de résistance en flexion des
céramiques monolithiques à température ambiante
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
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ii © ISO 2016 – All rights reserved
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Apparatus . 3
5.1 Testing machine . 3
5.2 Test fixture . 3
5.2.1 General. 3
5.2.2 Bearings . 4
5.2.3 Four-point fixture: semi-articulating . 4
5.2.4 Four-point fixture: fully articulating . 4
5.2.5 Three-point fixture: semi-articulating . 4
5.2.6 Three-point fixture: fully articulating . 5
5.2.7 Positioning of bearings . 5
5.2.8 Fixture material . 6
5.3 Micrometer . 6
6 Test pieces . 6
6.1 Test piece size . 6
6.1.1 Machined test pieces . 6
6.1.2 As-fired or heat-treated test pieces . 6
6.2 Test piece preparation . 7
6.2.1 General. 7
6.2.2 As-fired . 7
6.2.3 Customary machining procedure . 7
6.2.4 Component-matched procedure . 7
6.2.5 Basic machining procedure . 7
6.2.6 Parallelism, orthogonality and chamfer sizes . 8
6.2.7 Handling of test pieces . 9
6.2.8 Number of test pieces . 9
7 Procedure. 9
8 Calculation .11
9 Test report .12
10 Strength scaling factors .13
Annex A (informative) General information.14
Annex B (normative) Test fixtures .15
Annex C (informative) Typical fracture patterns in ceramic test pieces .21
Annex D (informative) Chamfer correction factors .23
Annex E (informative) Weibull scaling factors .26
Bibliography .28
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 ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 206, Fine ceramics.
This third edition cancels and replaces the second edition (ISO 14704:2008), which has been technically
revised.
iv © ISO 2016 – All rights reserved
INTERNATIONAL STANDARD ISO 14704:2016(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for flexural strength of
monolithic ceramics at room temperature
1 Scope
This International Standard specifies a test method for determining the flexural strength of monolithic
fine ceramics, and whisker- or particulate-reinforced ceramic composites, at room temperature and
applies to materials with grain size less than 200 µm. This test method may be used for materials
development, quality control, characterization and design data-generation purposes.
NOTE Since fracture is due to tensile stress, flexural strength data can be used to calculate a uniaxial tensile
strength considering the effect of the tested volume and Weibull-statistics. So, flexural strength is often used in
substitute for uniaxial tensile strength.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 3611, Geometrical product specifications (GPS) — Dimensional measuring equipment: Micrometers for
external measurements — Design and metrological characteristics
ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Calibration and verification of the force-measuring system
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
flexural strength
maximum nominal stress at fracture of a specified elastic beam loaded in bending
3.2
four-point flexure
configuration of flexural strength testing where a test piece is loaded equally by two bearings
symmetrically located between two support bearings
Note 1 to entry: See Figure 1, a) and b).
Note 2 to entry: The bearings may be cylindrical rollers or cylindrical bearings.
L = 40 mm ± 0,1 mm
a) Four-point-1/4 point flexure
L = 30 mm ± 0,1 mm
b) Four-point-1/3 point flexure
L = 30 mm ± 0,1 mm or 40 mm ± 0,1 mm
c) Three-point flexure
Key
1 loading bearings
2 support bearing
3 test piece
Figure 1 — Flexural test configurations
3.3
four-point-1/4 point flexure
specific configuration of four-point flexural strength testing where the inner bearings are situated one-
quarter of the support span away from the two outer bearings
Note 1 to entry: See Figure 1 a).
2 © ISO 2016 – All rights reserved
3.4
four-point-1/3 point flexure
specific configuration of four-point flexural strength testing where the inner bearings are situated one-
third of the support span away from the two outer bearings
Note 1 to entry: See Figure 1 b).
3.5
semi-articulating fixture
test fixture designed to apply uniform and even loading to test pieces that have flat and parallel surfaces
3.6
fully articulating fixture
test fixture designed to apply uniform and even loading to test pieces that may have uneven, non-
parallel or twisted surfaces
3.7
three-point flexure
configuration of flexural strength testing where a test piece is loaded at a location midway between
two support bearings
Note 1 to entry: See Figure 1 c).
Note 2 to entry: Four-point flexure (3.2) is usually preferred, since a large amount of material is exposed to the
maximum stress (see Annex A for more information).
4 Principle
A beam test piece with a rectangular cross-section is loaded in flexure until fracture. The load at
fracture, the test fixture and test piece dimensions are used to compute the flexural strength which
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