ISO 17167:2018
(Main)Fine ceramics (advanced ceramics, advanced technical ceramics) — Mechanical properties of monolithic ceramics at room temperature — Determination of flexural strength by the ring-on-ring test
Fine ceramics (advanced ceramics, advanced technical ceramics) — Mechanical properties of monolithic ceramics at room temperature — Determination of flexural strength by the ring-on-ring test
This document specifies a method for the determination of the nominal equibiaxial flexural strength by the ring-on-ring test of advanced monolithic technical ceramic materials at room temperature. This document is applicable to materials with a grain size less than 100 µm.
Céramiques techniques — Propriétés mécaniques des céramiques monolithiques à température ambiante — Détermination de la résistance à la flexion à l'aide de doubles anneaux
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 17167
First edition
2018-11
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Mechanical properties of monolithic
ceramics at room temperature —
Determination of flexural strength by
the ring-on-ring test
Céramiques techniques — Propriétés mécaniques des céramiques
monolithiques à température ambiante — Détermination de la
résistance à la flexion à l'aide de doubles anneaux
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Significance and use . 2
6 Apparatus . 2
6.1 Test machine . 2
6.2 Test jig . 3
6.3 Calliper or alternative calibrated device for the measurement of the test piece thickness . 4
6.4 Device for measuring the temperature and humidity . 4
7 Test pieces . 4
7.1 General . 4
7.2 Dimensions and tolerances . 5
7.3 Surface finish . 6
7.3.1 General. 6
7.3.2 Surface finishing I: as-fired . 7
7.3.3 Surface finishing II: grinding/lapping/polishing . 7
7.3.4 Surface finish III: finishing by agreed procedure . 7
7.3.5 Check of dimensions . 7
7.3.6 General requirements . 8
7.3.7 Number of test pieces . 8
7.4 Precautions . 8
8 Procedure. 8
9 Calculations. 9
10 Test report .10
Annex A (informative) Typical fracture patterns of ceramic test pieces after a ring-on-ring test .11
Bibliography .13
Foreword
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iv © ISO 2018 – All rights reserved
INTERNATIONAL STANDARD ISO 17167:2018(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Mechanical properties of monolithic ceramics
at room temperature — Determination of flexural strength
by the ring-on-ring test
1 Scope
This document specifies a method for the determination of the nominal equibiaxial flexural strength by
the ring-on-ring test of advanced monolithic technical ceramic materials at room temperature.
This document is applicable to materials with a grain size less than 100 µm.
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 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
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
equibiaxial flexural strength
σ
rr
maximum nominal stress at the test piece surface supported by the material at the instant of failure
when loaded in linear elastic equibiaxial bending by the ring-on-ring test
Note 1 to entry: The ring-on-ring test for the determination of flexural strength is often referred to as biaxial
bending test or equibiaxial bending test (see Reference [1]). These names should not be used without the
reference to the ring-on-ring test conditions as there are some other test arrangements for which the term is
used or could also be used, such as the ball-on-three-balls test, the punch-on-three-balls test, the ball-on-ring
test and the punch-on-ring test.
4 Principle
A round discoidal test piece with a constant thickness is positioned between two concentric rings of
different diameters and loaded by an axial force.
The nominal equibiaxial flexural strength is calculated from the axial force which acts during the
moment of fracture, the geometry of the test piece and the test arrangement, as well as the Poisson
ratio of the test piece material.
5 Significance and use
This test is intended to be used for material development and characterization, quality control and
design data acquisition purposes. The strength level determined by the test is calculated on the
basis of linear elastic bending behaviour of a round, disk-like thin plate on the assumption that the
material being tested is elastically homogeneous and isotropic and shows a linear (Hooke) stress-strain
behaviour.
The result obtained from a strength test is determined by a large number of factors associated with
the microstructure of the material, the surface finishing procedure applied in preparation of the test
pieces, the size and shape of the test piece, the mechanical function of the testing apparatus, the rate
of load application and the relative humidity (RH) of the ambient atmosphere. As a consequence of the
brittle nature of ceramics, there is usually a considerable range of results obtained from a number of
nominally identical test pieces. These factors combined mean that caution in the interpretation of test
results is required. For many purposes, and as described in this document, the results of strength tests
can be described in terms of a mean value and a standard deviation. Further statistical evaluation of
results is required for design data acquisition and can be desirable for other purposes (see ISO 20501).
This method places closely defined restrictions on the size and shape of the test piece and on the
function of the test apparatus in order to minimize the errors that can arise as a consequence of the test
procedure.
NOTE The basis for the choice of dimensions and tolerances of test pieces and of the requirements of the test
jig can be found in ISO 6474-1, ASTM C1499 and Reference [1].
All other test factors are required to be stated in the test report (see Clause 10) in order to allow inter-
comparison of material behaviours. It is not possible rigorously to standardize particular surface
finishes since these are not absolutely controllable in mechanical terms. The inclusion of a standard
grinding procedure (see 7.3) as one of the surface finish options in this method is intended to provide a
means of obtaining a minimum amount of residual grinding damage to the test material.
WARNING — The extrapolation of equibiaxial flexural strength data to other geometries of
stressing, to single-axial stressing, to other rates of stressing or to other environments should
be viewed with caution.
The information about the origin of fracture in an equibiaxial flexural strength test can be a valuable
guide to the nature and position of strength-limiting defects. Fractography of test pieces is highly
recommended (see e.g. ASTM C1499, Reference [1], Reference [2]) and Annex A. In particular, the test
can identify fracture origins as being edge defects (caused by edge preparation), surface defects (caused
by surface preparation) or internal defects (caused by manufacturing inhomogeneities such as pores,
large grains or impurity concentrations). Not all advanced monolithic technical ceramics are amenable
...
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