CEN/TS 14425-5:2004
(Main)Advanced technical ceramics - Test methods for determination of fracture toughness of monolitic ceramics - Part 5: Single-edge vee-notch beam (SEVNB) method
Advanced technical ceramics - Test methods for determination of fracture toughness of monolitic ceramics - Part 5: Single-edge vee-notch beam (SEVNB) method
This part of CEN/TS 14425 describes a method for the determination of the fracture toughness of advanced technical ceramics. The procedure makes use of V-notched bars, which are loaded in 4-point bending until failure. It is applicable to ceramics with a grain size or major microstructural feature size larger than about 1 µm.
Hochleistungskeramik - Prüfverfahren zur Bestimmung der Bruchzähigkeit von monolithischer Keramik - Teil 5: Verfahren für Biegeproben mit V-Kerb (SEVNB-Verfahren)
Céramiques techniques avancées - Méthodes d'essai pour la détermination de la résistance à la fracture des céramiques monolithiques - Partie 5: Méthode du faisceau à entaille en V sur bord simple (SEVNB)
Sodobna tehnična keramika – Preskusne metode za ugotavljanje odpornosti monolitske keramike proti lomljenju – 5. del: Metoda upogibnega preskusa z V-zarezo (metoda SEVNB)
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Standards Content (Sample)
SLOVENSKI STANDARD
01-januar-2005
6RGREQDWHKQLþQDNHUDPLND±3UHVNXVQHPHWRGH]DXJRWDYOMDQMHRGSRUQRVWL
PRQROLWVNHNHUDPLNHSURWLORPOMHQMX±GHO 0HWRGDXSRJLEQHJDSUHVNXVD]9
]DUH]R PHWRGD6(91%
Advanced technical ceramics - Test methods for determination of fracture toughness of
monolitic ceramics - Part 5: Single-edge vee-notch beam (SEVNB) method
Hochleistungskeramik - Prüfverfahren zur Bestimmung der Bruchzähigkeit von
monolithischer Keramik - Teil 5: Verfahren für Biegeproben mit V-Kerb (SEVNB-
Verfahren)
Céramiques techniques avancées - Méthodes d'essai pour la détermination de la
résistance a la fracture des céramiques monolithiques - Partie 5: Méthode du faisceau a
entaille en V sur bord simple (SEVNB)
Ta slovenski standard je istoveten z: CEN/TS 14425-5:2004
ICS:
81.060.30 Sodobna keramika Advanced ceramics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
TECHNICAL SPECIFICATION
CEN/TS 14425-5
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
August 2004
ICS 81.060.30
English version
Advanced technical ceramics - Test methods for determination
of fracture toughness of monolitic ceramics - Part 5: Single-edge
vee-notch beam (SEVNB) method
Céramiques techniques avancées - Méthodes d'essai pour Hochleistungskeramik - Prüfverfahren zur Bestimmung der
la détermination de la résistance à la fracture des Bruchzähigkeit von monolithischer Keramik - Teil 5:
céramiques monolithiques - Partie 5: Méthode du faisceau Verfahren für Biegeproben mit V-Kerb (SEVNB-Verfahren)
à entaille en V sur bord simple (SEVNB)
This Technical Specification (CEN/TS) was approved by CEN on 4 April 2004 for provisional application.
The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the CEN/TS can be converted into a European Standard.
CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available
promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)
until the final decision about the possible conversion of the CEN/TS into an EN is reached.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 14425-5:2004: E
worldwide for CEN national Members.
Contents Page
Foreword. 3
1 Scope. 4
2 Normative references . 4
3 Terms and definitions. 4
4 Principle . 4
5 Apparatus . 5
5.1 Razor blades. 5
5.2 Diamond paste . 5
5.3 Lubricant. 5
5.4 Test piece support . 5
5.5 Flexural strength test jig . 5
5.6 Mechanical testing machine . 6
5.7 Ultrasonic cleaning bath . 6
5.8 Micrometer. 6
5.9 Microscope . 6
5.10 Notch measuring device. 6
5.11 Drying oven . 6
5.12 Diamond slitting saw . 6
6 Test piece preparation. 7
6.1 Number of test pieces. 7
6.2 Test-piece dimensions . 7
6.3 Preparing the V-notch by hand. 7
6.4 Preparing the V-notches by machine (optional) . 10
7 Test procedure . 10
7.1 Determination of notch root radius. 10
7.2 Dimensions of test-piece. 11
7.3 Flexural strength test. 11
7.4 Measurement of notch depth. 12
7.5 Calculation of fracture toughness. 13
8 Precision and bias . 14
9 Test report . 14
Annex A (informative) Notch honing by machine . 16
Annex B (informative) Interlaboratory evaluation of the SEVNB fracture toughness test
procedures. 17
Bibliography . 19
Foreword
This document (CEN/TS 14425-5:2004) has been prepared by Technical Committee CEN/TC 184
“Advanced technical ceramics”, the secretariat of which is held by BSI.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to announce this Technical Specification: Austria, Belgium, Cyprus,
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
CEN/TS 14425 Advanced technical ceramics — Test methods for determination of fracture toughness
of monolithic ceramics consists of five parts:
Part 1: Guide to test method selection
Part 2: Single-edge pre-cracked beam (SEPB) method
Part 3: Chevron notched beam (CNB) (method
Part 4: Surface crack in flexure (SCF) method
Part 5: Single-edge V-notch beam (SEVNB) method
1 Scope
This part of CEN/TS 14425 describes a method for the determination of the fracture toughness of
advanced technical ceramics. The procedure makes use of V-notched bars, which are loaded in 4-
point bending until failure. It is applicable to ceramics with a grain size or major microstructural feature
size larger than about 1 µm.
2 Normative references
The following referenced documents are indispensable for the application 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.
EN 843-1, Advanced technical ceramics — Monolithic ceramics — Mechanical properties at room
temperature — Part 1: Determination of flexural strength
ENV 1006, Advanced technical ceramics — Monolithic ceramics — Guidance on the selection of test
pieces for the evaluation of properties
CEN/TS 14425-1, Advanced technical ceramics — Test methods for determination of fracture toughness
of monolithic ceramics - Part 1: Guide to test method selection
EN ISO 7500-1, Metallic materials - Verification of static uniaxial testing machines - Part 1:
Tension/compression testing machines (ISO 7500-1:1999)
EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
(ISO/IEC 17025:1999)
ISO 3611, Micrometer callipers for external measurement
3 Terms and definitions
For the purposes of this document, the terms and definitions given in CEN/TS 14425-1 apply.
4 Principle
This method of conducting a fracture toughness test is based on the preparation and fracture of bar
test pieces in which a sharp-tipped notch is machined. Using the technique of a reciprocating razor
blade and diamond paste, a narrow notch can be honed into a test piece using either a manual
method or a simple machine. Under well-controlled conditions a notch tip radius in the range of 1 µm
to 20 µm can be prepared depending on the grain size of the test material. For many materials this is
a close approximation to a sharp crack, and the method has been found to give fracture toughness
values very close to those of other methods such as the single-edge pre-cracked beam (SEPB)
method (prCEN/TS 14425-2) or the surface crack in flexure (SCF) method (prCEN/TS 14425-4). The
method has advantages of simplicity of notch production compared with using a sharp-tipped
diamond saw or a diamond impregnated wire in which the tip radius is normally greater than 50 µm.
The method is often easier to undertake compared with other methods of pre-cracking, and is
applicable to a wider range of materials outside the scope of these other methods.
The method has been extensively researched (see Bibliography) and has been evaluated in
1) 2)
ESIS /VAMAS round robin testing, the results of which are summarised in Annex B. This
recommended practice is based upon the ESIS/VAMAS single edge V-notch beam (SEVNB) round
robin testing.
The method may have some limitations for materials with grain sizes of less than 1 µm, for which the
assumption that the notch approximates to a sharp crack may not be valid.
5 Apparatus
5.1 Razor blades
Standard razor blades, preferably with a support along one edge but alternatively inserted into a
suitable holder.
NOTE 1 Razor blades thinner than about 0,2 mm may not be stiff enough by themselves for this task. If the
razor blades are not stiff enough, it is recommended to glue or screw the blades between two steel plates leaving
only about 2 mm of edge showing. It is recommended to use a razor blade with a tip angle of 30°, or smaller.
NOTE 2 Although it is possible to machine the notches entirely by hand, the use of a simple device in which
the test pieces are mounted and in which a razor blade primed with diamond paste is moved in a reciprocating
motion across the mounted test-pieces has a distinct advantage as this provides controlled loading and
directional stability to the razor blade, and sharper notches can generally be produced. An example is shown in
Annex A.
5.2 Diamond paste
Metallographic diamond paste in a viscous organic carrier and of fine grain size, typically 1 µm to
3 µm.
5.3 Lubricant
Suitable lubricating oil for lubricating the razor blade.
5.4 Test piece support
A flat plate or other suitable device for mounting test pieces during notch honing.
5.5 Flexural strength test jig
A three-point or, preferably, four-point flexural strength test jig operating in accordance with the
requirements of EN 843-1. The test piece is supported on two bearing edges perpendicular to its
length. The outer support bearing edges shall be parallel rollers of diameter 5,0 mm ± 0,2 mm and
shall be capable of rolling outward on flat support surfaces. One of the rollers shall additionally be
capable of rotating about an axis parallel to the length of the test piece such that torsional loading is
minimised. The two rollers shall be positioned initially with
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