SIST EN ISO 6872:2015

SLOVENSKI STANDARD
oSIST prEN ISO 6872:2013
01-november-2013
=RER]GUDYVWYR.HUDPLþQLPDWHULDOL,62',6
Dentistry - Ceramic materials (ISO/DIS 6872:2013)
Zahnheilkunde - Keramische Werkstoffe (ISO/DIS 6872:2013)
Médecine bucco-dentaire - Matériaux céramiques (ISO/DIS 6872:2013)
Ta slovenski standard je istoveten z: prEN ISO 6872
ICS:
11.060.10 =RERWHKQLþQLPDWHULDOL Dental materials
oSIST prEN ISO 6872:2013 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 6872:2013

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oSIST prEN ISO 6872:2013
DRAFT INTERNATIONAL STANDARD
ISO/DIS 6872
ISO/TC 106/SC 2 Secretariat: ANSI
Voting begins on: Voting terminates on:
2013-08-29 2014-01-29
Dentistry — Ceramic materials
Art dentaire — Produits céramiques
[Revision of third edition (ISO 6872:2008)]
ICS: 11.060.10
ISO/CEN PARALLEL PROCESSING
This draft has been developed within the International Organization for
Standardization (ISO), and processed under the ISO lead mode of collaboration
as defined in the Vienna Agreement.
This draft is hereby submitted to the ISO member bodies and to the CEN member
bodies for a parallel five month enquiry.
Should this draft be accepted, a final draft, established on the basis of comments
received, will be submitted to a parallel two-month approval vote in ISO and
THIS DOCUMENT IS A DRAFT CIRCULATED
formal vote in CEN.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
To expedite distribution, this document is circulated as received from the
IN ADDITION TO THEIR EVALUATION AS
committee secretariat. ISO Central Secretariat work of editing and text
BEING ACCEPTABLE FOR INDUSTRIAL,
composition will be undertaken at publication stage.
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 6872:2013(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2013

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oSIST prEN ISO 6872:2013
ISO/DIS 6872:2013(E)

Copyright notice
This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as
permitted under the applicable laws of the user’s country, neither this ISO draft nor any extract
from it may be reproduced, stored in a retrieval system or transmitted in any form or by any means,
electronic, photocopying, recording or otherwise, without prior written permission being secured.
Requests for permission to reproduce should be addressed to either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
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Reproduction may be subject to royalty payments or a licensing agreement.
Violators may be prosecuted.
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oSIST prEN ISO 6872:2013

Contents
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Types, Classes and their Identification . 4
5 Requirements . 4
6 Sampling . 5
7 Test Methods .……………………………………………………………………………………………………. . 5
8 Information and Instructions . 14
9 Packaging, Marking and Labelling . 15
Annex A (informative) Fracture Toughness . 19
Annex B (informative) Weibull Statistics . 25


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oSIST prEN ISO 6872:2013
ISO/CD 6872
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of ISO 6872 may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 6872 was prepared by Technical Committee ISO/TC 106, Dentistry, Subcommittee
SC 2, Prosthodontics.

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oSIST prEN ISO 6872:2013

Introduction
Specific qualitative and quantitative requirements for freedom from biological hazard are not included in this
International Standard, but it is recommended that, in assessing possible biological or toxicological hazards,
reference be made to ISO 10993-1 and ISO 7405.
This edition cancels and replaces ISO 6872:2008. The following changes were made to the previous edition of ISO
6872:
• The strength table has been expanded to take into account the different test methods and specimen sizes.
• New 2008 ISO standard 23146 for fracture toughness by SEVNB has been added as an alternative in the Annex.
It has a rigorous procedure developed by ISO TC 206, Fine Ceramics.
• A restriction on the use of the SEVNB method for fracture toughness determination for 3Y-TZP has been added.
In most cases, the notch cannot be made sharp enough with a razor blade.
• Maximum chamfer size on bend bars has been reduced a little bit for the case of the thin specimens.
• A recommendation is added that the chamfers to bend bars be ground lengthwise.
• Recommendations to grind lengthwise were added to the bend bar preparation step in paragraph 7.3.1.2.2
• The Y equations for SEVNB fracture toughness in 3–point have been refined and expanded to cover more
configurations.
• Modification to Table 1 changing “aesthetic” to “monolithic”.

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oSIST prEN ISO 6872:2013
ISO/CD 6872

Dentistry — Ceramic Materials
1 Scope
This International Standard specifies the requirements and the corresponding test methods for dental ceramic materials
for fixed all-ceramic and metal-ceramic restorations and prostheses.
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 3696: Water for analytical laboratory use – Specification and test methods.
ISO 1942: Dentistry – Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1942 and the following apply:
3.1  Material

3.1.1
addition ceramic
dental ceramic material which is fired at a reduced temperature and is normally applied to restore contact points on a
dental restoration or prosthesis

3.1.2
dental ceramic
inorganic, non-metallic material which is specifically formulated for use, when processed according to manufacturers
instructions, to form the whole or part of a dental restoration or prosthesis

3.1.3
dental porcelain
predominantly glassy dental ceramic material used mainly for aesthetics in a dental restoration or prosthesis

3.1.4
dentine ceramic
dental ceramic material used to form the overall shape and basic colour of a dental restoration or prosthesis,
simulating the natural tooth dentine

3.1.5
enamel ceramic
dental ceramic material used to overlay either partially or wholly the dentine ceramic and also to form the more
translucent incisal third of a dental restoration or prosthesis, simulating the natural tooth enamel


1

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3.1.6
flame-sprayed dental ceramic
dental ceramic core or substructure layer formed via the technique of flame spraying
3.1.7
glass-ceramic (dental)
dental ceramic material formed by the action of heat treatment on a glass, in order to cause initiation and growth of a
wholly or predominantly crystalline microstructure

3.1.8
glass-infiltrated dental ceramic
dental ceramic core or substructure layer which is porous and is subsequently densified by the infiltration of
specialised glass at elevated temperature

3.1.9
glaze ceramic
dental ceramic material which is overlayed and fired at a reduced temperature compared to dentine or enamel
ceramic, to produce a thin coherent sealed surface, the level of gloss being determined by the firing conditions

3.1.10
liner
dental ceramic material used on all-ceramic substructure forming a layer that provides a background colour upon
which dentine or opaceous dentine may be applied to achieve overall aesthetics

3.1.11
modelling fluid
liquid with which a dental ceramic powder is mixed, in order to shape or model it into its required form prior to firing

3.1.12
opaceous dentine ceramic
Dental ceramic material having a higher opacity than a dentine ceramic material, but which may still be used to
contribute to the overall shape and basic colour of a dental restoration or prosthesis, simulating the natural tooth
dentine

3.1.13
opaque dental ceramic
dental ceramic material, which when applied to a metallic substructure, according to manufacturer’s instructions, acts
to bond to the metal surface, forming a layer that provides a background colour and interface upon which other dental
ceramic materials may be applied to achieve overall aesthetics

3.1.14
shoulder ceramic
dental ceramic material used to form shape and colour at the marginal area of the dental restoration or prosthesis,
simulating natural tooth dentine in this area


3.1.15
stain ceramic
dental ceramic powder or paste which is normally intensely coloured and which is formulated to be used either
internally or externally, during the build up of a dental restoration or prosthesis, to simulate details within or on the
surface respectively as are found in natural teeth

3.1.16
substructure (core) dental ceramic
Predominantly polycrystalline dental ceramic material that forms a supporting substructure upon which one or more
layers of dental ceramic or dental polymer material are applied, either partially or totally, to form a dental restoration or
prosthesis

3.1.17
monolithic ceramic
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oSIST prEN ISO 6872:2013

a monolithic dental ceramic is substantially made of a single, uniform material. A thin layer of glaze (staining
technique) may be applied.

3.2 Processing

3.2.1
air firing dental ceramic
firing of dental ceramics under ambient atmospheric pressure

3.2.2
dental CAD/CAM
computer aided design/computer aided manufacture (CAD/CAM) procedures to manufacture a dental restoration or
prosthesis normally including the following stages: 1. . a digital scanning procedure of the model, wax-up or intra-
orally to produce a 3D data set. 2.software manipulation of the 3D data set to design the prosthesis and 3. a
computer directed machine tool that performs the manufacturing process

3.2.3
condensation of dental ceramic
powder process whereby a slurry of dental ceramic powder is vibrated to compact the powder, prior to sintering

3.2.4
injectable, castable, or pressable dental ceramic
dental ceramic material, normally in the form of a pellet or ingot (often pre-sintered), designed for use in a specialised
furnace, which enables the ingot to be injected/cast/pressed into a mould, prepared via the lost wax technique

3.2.5
sintering of a dental ceramic
process whereby heat and potentially other process parameters ( e.g. pressure and atmosphere) are applied to a
ceramic powder or powder compact, in order to densify the ceramic into its required form. Note: “firing” and “sintering”
are used interchangeably in this document (“firing” connoting the application of heat to drive sintering)

3.2.6
vacuum firing dental ceramic
firing of dental ceramics at reduced pressure (i.e. under vacuum) to yield the required density and associated
aesthetics, especially degree of translucency. Dental ceramic for vacuum firing have a specific particle size distribution
to reduce the entrapment of porosity

3.3 Properties

3.3.1
class of dental ceramic
classification of a dental ceramic material according to its intended function

3.3.2
fracture toughness
conventional fracture mechanics parameter indicating the resistance of a material to crack extension (propagation)

3.3.3
glass transition temperature
the approximate mid-point of the temperature range over which a glass transforms between elastic and viscoelastic
behaviour, characterized by the onset of a rapid change in its coefficient of thermal expansion

3.3.4
glaze
surface appearance obtained when the gloss is clinically and aesthetically acceptable

4   Types, classes and their identification

For the purposes of this International Standard, dental ceramics are designated into two types:
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 Type I: ceramic products that are provided as powders, pastes or aerosols;
 Type II: all other forms of ceramic products.
Ceramics are divided into six classes according to their intended clinical use according to descriptions in Table 1.
If colour is added to a ceramic powder for identification purposes, the colour coding given in Table 2 is
recommended.
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Table 1 – Classification of ceramics for fixed prostheses by intended clinical use, with required mechanical
and chemical properties.

Class Recommended Clinical Indications Mechanical and Chemical Properties

 Flexural strength Chemical Solubility
-2
MPa μg·cm

minimum (of mean) maximum

1 a. Aesthetic ceramic for coverage of a 55 biaxial 100
metal or a ceramic substructure.

  50 3-point
b. Monolithic-ceramic: single-unit anterior
  40 4-point

prostheses, veneers, inlays, or onlays.
2 a. Monolithic -ceramic: adhesively 115 biaxial a. 100

cemented, single-unit, anterior or
     100 3-point
posterior prostheses.

     90 4-point

b. 2000
b. Adhesively cemented, substructure

ceramic for single-unit anterior or

posterior prostheses.

3 Monolithic-ceramic: non-adhesively  340 biaxial 100
cemented, single-unit, anterior or
   300 3-point

posterior prostheses.
   265 4-point

4 a. Substructure ceramic for non- 340 biaxial 2000
adhesively cemented, single-unit,
   300 3-point

anterior or posterior prostheses.
   265 4-point
b. Substructure ceramic for three-unit

prostheses not involving molar
restoration.

5 Substructure ceramic for three-unit 570 biaxial 2000
prostheses involving molar restoration.
   500 3-point

   440 4-point

6 Substructure ceramic for prostheses 910 biaxial 100

involving 4 or more units.
  800 3-point

  710 4-point

Note: The higher recommended clinical indications may include lower indications, if indicated by the
manufacturer.
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Table 2 - Recommended colour coding for the identification of Type I dental ceramic powders.

Material Colour coding

Dentine Pink


Enamel Blue

Fluorescent Yellow

Highly chromatic dentine Orange

Opalescent enamel Blue-green


Modifying enamel Purple

(e.g., translucent, clear)

5   Requirements
5.1 Uniformity
The inorganic pigment(s) used to produce the colour of a fired dental ceramic and any organic colorants (for colour
coding) shall be uniformly dispersed throughout the dental ceramic material and, in powdered ceramic products, no
segregation of the pigment(s) shall take place when the powder is mixed as in 7.1.3. Check by visual inspection.
5.2 Freedom from extraneous materials

5.2.1 Dental ceramic materials shall be free from extraneous materials, when assessed by visual inspection.
-1
5.2.2 Dental ceramic materials shall not have an activity concentration of more than 1,0 Bqg of uranium 238.
Test in accordance with 7.2.2.in 7.2.
5.2.3 Any colorants used to colour code the ceramic powder as per Table 2 are recommended to be food quality

organic materials.
5.3 Mixing and condensation properties, type I ceramics
When mixed as in 7.1.3 with water or the modelling fluid recommended by the manufacturer, a dental ceramic
powder shall not form lumps or granules when assessed by visual inspection.
The paste so formed shall be suitable for making the indicated restorations and prostheses by condensation of
successive layers. When the paste is condensed as in 7.1.4, it shall not crack or crumble when assessed by visual
inspection during drying.
5.4 Physical and chemical properties

The physical and chemical properties of ceramic test specimens tested in accordance with the relevant methods,
detailed for Type I and Type II ceramics in clause 7, shall comply with the requirements specified in Table 1. The
-6 -1
coefficient of thermal expansion of the ceramics shall not deviate by more than 0,5 x 10 K from the value stated
by the manufacturer (see 8.2.2). The glass transition temperature of the ceramics shall not deviate by more than
20 ºC from the value stated by the manufacturer (see 8.2.2).
5.5 Biocompatibility

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oSIST prEN ISO 6872:2013

See the introduction for guidance on biocompatibility.
5.6 Shrinkage factor
The absolute accuracy of the shrinkage factor by which the dimensions of the partially sintered material is to be
divided as provided under 9.2.2 c) shall be  0.002
6   Sampling

6.1 Type I ceramics

Use retail packages from the same batch containing enough material to carry out the specified tests, plus an
allowance for repeated tests, if necessary. Where there is more than one shade in a class of dental ceramic,
perform test with a colour / shade most commonly used. All of a material tested, shall be of the same lot.
Sufficient quantities of essential modelling fluids shall be obtained, if their use is recommended by the
manufacturers. The quantities shall be those recommended by the manufacturer concerned.
6.2 Type II ceramics

All of a material procured for testing in accordance with this International Standard shall be of the same lot.
7  Test methods
7.1  Preparation of test specimens
For detailed instructions, see the individual test methods.
For type I specimens (unless otherwise stated or inconsistent with the text) the apparatus detailed in
7.1.2 along with the conditions for mixing, condensation and firing (7.1.3 to 7.1.5) apply to all test methods.

7.1.1 Components of test specimens, type I ceramics

The liquid used in the preparation of test specimens shall be water that complies with the requirements for grade 3
water (ISO 3696) or, when applicable, the modeling fluid recommended by the manufacturer of the dental ceramic
powder. The required amount of powder shall be taken from the appropriate pool of powder obtained in
accordance with 6.1

7.1.2  Apparatus for mixing

All apparatus for mixing shall be clean and dry.

7.1.2.1  Glass slab or mixing palette.

7.1.2.2  Spatula, made from a material that is not readily abraded by the dental ceramic powder (glass is
recommended). Instruments used for the mixing procedure shall be made of materials that do not contaminate the
ceramic material.
7.1.2.3  Open multipart mould from which the condensed specimen may be removed without distortion.

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7.1.2.4  Vibration system (table or mechanical brush) capable of vibrating at a frequency of 50 Hz to 60 Hz or in
accordance with the manufacturer’s instructions.

7.1.3  Method of mixing
Combine the water or modelling liquid and the ceramic powder in the proportions recommended by the
manufacturer. Avoid vigorous mixing which will tend to incorporate air bubbles with the paste and, both during and
after mixing, examine for compliance with 5.1 and 5.2.1.

7.1.4  Procedure for specimen fabrication
Overfill the mould with dental ceramic paste, and vibrate. When excess liquid appears at the free surface of the
specimen, place a paper tissue (or similar absorbent material) on the surface of the specimen, and remove the
excess liquid continually by replacing the tissue as soon as it becomes saturated with liquid. Continue vibration
and absorption until no further liquid can be removed, and then level the free surface of the condensed specimen
by means of a suitable instrument (a bevelled glass microscope slide is ideal for this purpose). After removing the
specimen from the mould, place it on a firing tray, dry it and check for compliance with 5.3.
NOTE: Other forming methods, such as dry pressing, are acceptable for specimen fabrication.
7.1.5 Firing

Position the specimens in the furnace so that they will be uniformly fired, and on a substrate to which they will not
adhere and from which there will be no pick-up of material. Obtain guidance from the manufacturer for the firing of
test specimens. These specimens should be fired according to manufacturer instructions so that their final density
and thermal history is representative of that found for indicated restorations or prostheses, specific for the given
test specimen, which is different from the IFU.
7.2   Radioactivity of dental ceramic

7.2.1  Preparation of samples

7.2.1.1   Type I ceramics

A 50 g sample as-manufactured is suitable, collected as described in 6.1.

7.2.1.2  Type II ceramics
Mill powder using tungsten-carbide milling media or other appropriate media (to avoid contamination by radioactive
species). Sieve and obtain 50 g of powder with a particle size less than 75 m.

7.2.2   Counting procedure
Use a sample volume of 50 g bulk powder and determine the activity concentration of uranium-238 by neutron
activation or gamma spectroscopy (with gamma spectroscopy techniques must be used to screen for adulteration).

7.2.3 Assessment of results
Each sample tested shall comply with the requirement in 5.2.2.

7.3  Flexural strength
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Three flexural test methods are acceptable: (a) three-point bending; (b) four-point bending; and (c) biaxial flexure
(piston-on-three-ball).
7.3.1  Three-point and four-point bending tests
7.3.1.1  Apparatus
7.3.1.1.1 Universal mechanical testing machine capable of a cross-head speed of (1 ± 0,5) mm/min and an
ability to measure applied loads of between 10 N and 2500 N (± 1%).
7.3.1.1.2  Flexural test fixtures
7.3.1.1.2.1 Fixture for three-point bending consisting of support rollers (1,5 mm to 5 mm ± 0,2 mm, in diameter)
positioned with their centers 12,0 mm to 40,0 mm (± 0,5 mm) apart.  The load shall be applied at the midpoint
between the supports by means of a third roller (1,5 mm to 5 mm ± 0.2 mm, in diameter). Rollers should be made
from hardened steel or other hard material having a hardness greater than 40 HRC (Rockwell C-scale) and have a
smooth surface with a roughness less than 0,5 μm R .  It is recommend that the actual spacing between the
a
support roller centers (L) be measured to within 0,1 mm.
7.3.1.1.2.2 Fixture for four-point bending consisting of a 1/4-point test configuration such that the test piece is
loaded by two inner bearing rollers located ¼ of the total span (L) from the outer support bearing rollers (see Figure
1).
Support rollers (1,5 mm to 5 mm ± 0,2 mm, diameter) shall be positioned with their centers are L = 16,0 mm to 40,0
mm apart. Rollers shall be made from hardened steel or other hard material having a hardness greater than 40
HRC (Rockwell C-scale) and have a smooth surface with a roughness less than 0,5 μm R . The two loading
a
rollers, of identical material and size to the support rollers, shall be located at the quarter points yielding an inner
span (L/2 or L in Fig. 1) of 8,0 mm to 20,0 mm. The loading arrangement shall ensure that equal forces are
i
applied to the loading rollers and that torsional loading is minimized. It is recommend that the actual spacing
between the roller centers (L for support and L/2 for inner) be measured to within 0,1 mm. It is recommended that
the inner span be centered over the support span to within 0,1 mm).


    L/4  L/2





L

Figure 1 – Schematic of the four-point-1/4-point fixture configuration
(Note: moment arm = L/4).

7.3.1.2   Preparation of test specimens
7.3.1.2.1 Test specimen dimensions and test parameters
Dimensions:
Specimens for three-point and four-point bending testing have a rectangular cross section and most preferably an
edge chamfer as per the diagram in Figure 2 and dimensions listed below. The edge chamfer should be ground or
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rounded lengthwise, along the long axis of the specimen, so that grinding damage and chipping is minimized. The
edge chamfer may be ground prior to final sintering if kept within below values after final sintering.
Specimen dimensions:
Width   w = (4±0,2) mm (dimension of the side at right angles to the direction of the applied load)
Thickness b = (2,1±1,1) mm (with 3,0 mm recommended; dimension of the side parallel to the direction of the
applied load)
Chamfer   c = (0,12 ± 0,03) mm (with a maximum of 0,10 mm recommended for small thickness specimens (b <
2,0 mm))

Test parameters:
Test span:
For four-point bending; L in millimetres (centre-to-centre distance between outer support roller, see Figure 1. In the
four-point ¼ configuration specified, the moment arm = L/4).
For three-point bending; l in millimetres (centre-to-centre distance between support rollers).
Breaking load: P in Newtons
Specimen lengths shall be at least 2 mm longer than the test span (L or l) and the ratio of thickness to length (b/L
or b/l) shall be ≤ 0,1.

c

o
45

b

h


w


    Figure 2 – Specification of indicated dimensions.

7.3.1.2.2  Type I ceramics
Prepare at least 10 and preferably 30 specimens of dimensions as specified in 7.3.1.2.1. Use a mould
appropriately sized to allow for dimensional changes resulting from sintering and finishing. Fire the specimens in
accordance with the manufacturer’s instructions modified as needed due to specimen dimensions. Grind each
specimen so as to produce a rectangular
...