Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for fracture toughness of monolithic ceramic thin plates at room temperature

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 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.

Céramiques techniques (céramiques avancées, céramiques techniques avancées) — Méthode d’essai pour déterminer la ténacité des plaques minces en céramique monolithique à température ambiante

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Status
Published
Publication Date
16-Jul-2018
Technical Committee
Drafting Committee
Current Stage
6060 - International Standard published
Start Date
17-Jul-2018
Completion Date
17-Jul-2018
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ISO 21113:2018 - Fine ceramics (advanced ceramics, advanced technical ceramics) -- Test method for fracture toughness of monolithic ceramic thin plates at room temperature
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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 21113:2018(E)
ISO 2018
---------------------- Page: 1 ----------------------
ISO 21113:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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below or ISO’s member body in the country of the requester.
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Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved
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ISO 21113:2018(E)
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

© ISO 2018 – All rights reserved iii
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ISO 21113:2018(E)
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

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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

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.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 206, Fine ceramics.

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 © ISO 2018 – All rights reserved
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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/
© ISO 2018 – All rights reserved 1
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ISO 21113:2018(E)
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
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ISO 21113:2018(E)
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
© ISO 2018 – All rights reserved 3
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ISO 21113:2018(E)
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 main dimensions of

the test pieces. The parallelism tolerance on the opposite longitudinal side L × B face shall be 0,015 mm

as defined in ISO 1101. The longitudinal side faces shall intersect with the large faces perpendicularly.

The maximum variation in perpendicularity shall not exceed 0,01 mm. The variation of thickness, B –

max

B , shall be less than 10 % of the average thickness, B , which is determined from the thicknesses at

min ave
three or more points.
Total length Width Thickness
Specimen L W B
mm mm mm
I ≥36 4,0 ± 0,2 0,2 to 1,0
II ≥45 4,0 ± 0,2 0,2 to 1,0
Figure 2 — Dimensions of specimen

The longitudinal side L × B faces of as-cut thin plate usually intersect with the large face at a slightly

oblique angle or have burrs and/or chippings as described in Figure 3. Both cross section and the

longitudinal side L × B faces shall be observed with an optical microscope at a magnification of about

20 × or greater. The longitudinal side faces shall be polished until they form a right angle to the large

surfaces.
Figure 3 — Guidelines for the unacceptable cross sections of specimen

It is recommended that the cut specimen width is slightly larger than 4,0 mm taking into account

the reserving space for polishing. It is also recommended that the length, L, of the test piece is kept

constant, for example 40 mm ± 0,2 mm, unless special requests exist. Otherwise, different brass beams

with stops need to be made for the ease of centring of the notch and precrack in the fixture every time

the length of the test piece is changed.
4 © ISO 2018 – All rights reserved
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ISO 21113:2018(E)
6.2 Test piece preparation

Machining aspects unique to the precracked method and V-notched method shall be used as specified

in Annexes A and B, respectively.
6.3 Number of test piece

At least eight test pieces shall be prepared for a flexural-strength test, of which five are required for

valid results.
7 Test methods
7.1 Three or four-point bending fracture test

7.1.1 Insert the test piece into the slit of the test jig slowly, with the precracked or V-notched face on

the outer-support rollers as shown in Figure 1. Ensure that the precrack is on the centre of supporting

roller pins to within ± 0,1 mm. Set the loading roller pin(s) on the specimen and hold the pin(s) until

the loading member is placed on it, otherwise the loading roller pin(s) will drop off. When the loading

member is positioned, turn the loading member so that the tooth fits in the longitudinal groove of the

support member. If the tooth of the loading member is out of the longitudinal groove, the loading member

and loading roller will tilt slightly, and compressive force will be applied obliquely to the test specimen.

7.1.2 Apply a compressive load to the loading member at a cross-head speed of 0,5 mm/min until the

specimen fractures, and measure the maximum load, P , to an accuracy of 1 %.
7.2 Measurement of thickness and width of test piece

The measurement of the thickness and width of the specimen shall be carried out using a micrometer

or other device accurate to the nearest 0,01 mm.
7.3 Measurement of precrack length

For the single-edge precracked plate method, measure the precrack length of the test piece after

fracture as specified in Annex C.
8 Evaluation of validity of measured value
A valid test shall meet the requirements specified in Annexes B and C.
© ISO 2018 – All rights reserved 5
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ISO 21113:2018(E)
9 Calculation

Calculate the fracture toughness value, K or K , from the measured values for each specimen

Ipp Ic,SEVNP

according to Formulae (1) to (4). Obtain the average value of fracture toughness of five or more

specimens conforming to the specification given in Clause 8 and round off to one decimal place.

Pd× 3
 
12/
f 1
KorK = αα×Y (1)
IppIc,SEVNP
 
32/
BW×  
where, in the case of three-point bend specimen I,
23 4
Y()α =+1,,964−2,837αα13 711 −23,250αα+24,129 (2)
In the case of four-point bend specimen I and II,
12/
 
Pd×()−d
3 α
f 12
KorK = ×Y α (3)
 ()
IppIc,SEVNP
32/ 32/
BW×  (1−)α 
 
(,3490−−,,68αα+1351)(αα)
Y()αα= , −1,326 − (4)
1 9877
()1+α
where
1/2
K is the fracture toughness, single-edge precracked plate method, in MPa·m ;
Ipp
1/2
K is the fracture toughness, single-edge V-notch plate method, in MPa·m ;
Ic,SEVNP
P is the fracture load, in MN;
B is the specimen thickness, in m;
W is the specimen width, in m;
d is the support span, in m;
d is the loading span (d > d ), in m;
2 1 2

α is the average relative precrack length or the average relative V-notch depth;

Y is the stress intensity shape factor.

The mean fracture toughness, K or K , and the standard deviation, s, are given by

Ipp Ic,SEVNP
Formulae (5) and (6), respectively.
6 © ISO 2018 – All rights reserved
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ISO 21113:2018(E)
n n
K K
∑ Ipp,i ∑ Ic,SEVNP,i
1 1
K = or K = (5)
Ipp Ic,SEVNP
n n
12/ 12/
n n
   
2 2
   
()KK− ()KK−
Ipp Ic,SEVNP
∑ Ipp,i ∑ Ic,SEVNP,i
   
1 1
s= or s= (6)
   
n−1 n−1
   
   
   
where

K is the fracture toughness of the ith specimen, single-edge precracked plate method;

Ipp,i

K is the fracture toughness of the ith specimen, single-edge V-notch plate method;

Ic,SEVNP,i
n is the total number of specimens.
10 Test report
The test report shall include the following information:
a) type of material, code, batch number, date of manufacture;

b) type of test method (either single-edge precrack plate method or single-edge V-notch plate method);

c) number of specimens conforming to the specifications given in Clause 8;

d) measured fracture toughness values, K or K , the average and the standard deviation, in

Ipp Ic,SEVNP
megapascal metres to the power half;
e) specimen dimensions: thickness, B, width, W, in millimetres;

f) precracking conditions (e.g. depth and width of notch and pop-in load) or a description of the

method employed to prepare the V-notches;
g) environment conditions, relative humidity and temperature;
h) maximum load before fracture, P , in newtons;

i) precrack lengths, l, in millimetres, or depth of the V-notches, a, notch-root width, S, in millimetres,

and V-notch angle, β.
© ISO 2018 – All rights reserved 7
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ISO 21113:2018(E)
Annex A
(norm
...

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