ISO 21113:2018

INTERNATIONAL ISO
STANDARD 21113
First edition
2018-07
Fine ceramics (advanced ceramics,
advanced technical ceramics) — Test
method for fracture toughness of
monolithic ceramic thin plates at
room temperature
Céramiques techniques (céramiques avancées, céramiques techniques
avancées) — Méthode d’essai pour déterminer la ténacité des plaques
minces en céramique monolithique à température ambiante
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 . 2
5 Apparatus . 2
5.1 Bend testing machine. . 2
5.2 Bend test fixture. . 2
6 Test piece dimension and preparation. 4
6.1 Shape and dimensions of test piece . 4
6.2 Test piece preparation . 5
6.3 Number of test piece . 5
7 Test methods . 5
7.1 Three or four-point bending fracture test . 5
7.2 Measurement of thickness and width of test piece . 5
7.3 Measurement of precrack length . 5
8 Evaluation of validity of measured value . 5
9 Calculation . 6
10 Test report . 7
Annex A (normative) Test piece preparation for the precracked plate method .8
Annex B (normative) Test piece preparation for the V-notch plate method .13
Annex C (normative) Measurement of precrack length and evaluation of validity of
measured value for the precracked plate method .19
Bibliography .21
Foreword
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iv © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 21113:2018(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for fracture toughness of
monolithic ceramic thin plates at room temperature
1 Scope
This document describes a test method for the determination of the fracture toughness of monolithic
ceramic thin plates at room temperature by the single-edge precracked plate method or the single-edge
V-notch plate method.
This document is intended for use with monolithic ceramics and whisker- or particulate-reinforced
ceramics which are regarded as macroscopically homogeneous. It does not include continuous-fibre-
reinforced ceramics composites. This document is applicable to ceramic thin plates with a thickness of
0,2 mm to <1,0 mm.
The single-edge V-notch plate method can be applied to monolithic ceramics with a grain size larger
than about 1 μm. The use of this method is inappropriate for yttria tetragonal zirconia polycrystal
material (Y-TZP), which consists of homogeneous fine submicron grains. The method might also be
unsuitable for some other very tough or soft ceramics in which a sharp crack does not form at the root
of the V-notch.
This document is for material development, material comparison, quality assurance, characterization,
reliability and design data generation.
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 1101, Geometrical Product Specifications (GPS) — Geometrical tolerancing — Tolerances of form,
orientation, location and run-out
ISO 4287, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Terms, definitions
and surface texture parameters
ISO 7500-1, Metallic materials — Verification of static uniaxial testing machines — Part 1: Tension/
compression testing machines — Verification and calibration of the force-measuring system
ISO 15732, Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for fracture
toughness of monolithic ceramics at room temperature by single edge precracked beam (SEPB) method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 15732 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/
4 Principle
This method is to obtain the fracture toughness value from the precrack length or the V-notch depth,
specimen dimensions and distance between the bending supports by measuring the fracture load of
specimen according to the three- or four-point bending fracture test of a single-edge precracked plate
specimen or a V-notched plate specimen. For the single-edge precracked plate method, a straight-
through pop-in precrack is induced in the specimen via three-point bending a saw-notched test
specimen bonded to a brass beam. For the V-notch plate method, a sharp-tipped notch is machined
using the technique of a reciprocating razor blade and diamond paste.
The use of the single-edge V-notch plate method for materials with grain size less than 1 μm is not
recommended, since the assumption that the notch approximates to a sharp crack is not established.
Users should strive to minimize the notch-root radius in the test pieces. This document places a
provisional criterion that the notch-root radius should be similar to or less than twice the average grain
size of the material.
5 Apparatus
5.1 Bend testing machine.
A suitable testing machine capable of applying a uniform cross-head speed shall be used. The testing
machine shall be in accordance with ISO 7500-1, with an accuracy of 1 % of the indicated force at
fracture.
5.2 Bend test fixture.
The general features of the bend test fixture are illustrated in Figure 1. The bend test fixture shall be
symmetrical about the centre line shown. The fixture shall have a thin slit in which the test specimen
can stand vertically on the supporting roller pins. The width of the slit shall be about 0,03 mm larger
than the specimen thickness. The loading roller pin for the three-point bend test is placed in the
positioning groove of the supporting member as shown in Figure 1 (a). The width of the positioning
groove should be about 0,05 mm larger than the diameter of the roller pin. The left and right loading
roller pins for the four-point bend test are placed in each positioning groove of the supporting member
as shown in Figure 1 (b) and are held against the stops and pillars. For both three-point and four-point
bend tests, the supporting roller pins are held against the stops and pillars. The loading member has a
tooth, which is put in the longitudinal groove of the supporting member to prevent the loading roller pin
from tilting so that it can push the specimen vertically. Other types of fixtures are acceptable; however,
compression force shall be applied vertically on the top surface of the specimen. Materials composing
the parts of the roller pins to be used shall be made of a material free from plastic deformation and risk
of fracture. The diameter of loading roller pin and supporting roller pins shall be between 4,0 mm and
5,0 mm. The surface roughness of the rollers, Ra, as defined in ISO 4287 shall be not more than 0,4 μm.
2 © ISO 2018 – All rights reserved

a) Three-point bend test fixture
b) Four-point bend test fixture
Key
1 loading ball 7 precrack or V notch
2 loading member with round head 8 supporting roller pins
3 loading member 9 stops and pillars
4 tooth of the loading member 10 supporting member
5 loading roller pins 11 longitudinal groove for the tooth of the loading member
6 specimen 12 slit for the specimen
Support span Loading span
Diameter of roller
pins
Bending mode Specimen d d
1 2
mm mm mm
3-point bend I 4,0 to 5,0 30 ± 0,3 —
4-point bend I 4,0 to 5,0 30 ± 0,3 10 ± 0,2
4-point bend II 4,0 to 5,0 40 ± 0,4 20 ± 0,2
Figure 1 — Bend test fixtures
6 Test piece dimension and preparation
6.1 Shape and dimensions of test piece
Prepare plate test pieces of rectangular cross-section. Figure 2 shows the shape and mai
...