EN 623-5:2009

SLOVENSKI STANDARD
01-november-2009
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SIST ENV 623-5:2007
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Advanced technical ceramics - Monolithic ceramics - General and textural properties -
Part 5: Determination of phase volume fraction by evaluation of micrographs
Hochleistungskeramik - Monolithische Keramik - Allgemeine und strukurelle
Eigenschaften - Teil 5: Bestimmung des Volumenanteils von Phasen durch Auswertung
von Mikrogefügeaufnahmen
Céramiques techniques avancées - Céramiques monolithiques - Propriétés générales et
textures - Partie 5: Détermination de la fraction volumique de phase par évaluation des
microphotographies
Ta slovenski standard je istoveten z: EN 623-5:2009
ICS:
81.060.30 Sodobna keramika Advanced ceramics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 623-5
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2009
ICS 81.060.30 Supersedes ENV 623-5:2002
English Version
Advanced technical ceramics - Monolithic ceramics - General
and textural properties - Part 5: Determination of phase volume
fraction by evaluation of micrographs
Céramiques techniques avancées - Céramiques Hochleistungskeramik - Monolithische Keramik -
monolithiques - Propriétés générales et textures - Partie 5: Allgemeine und strukurelle Eigenschaften - Teil 5:
Détermination de la fraction volumique de phase par Bestimmung des Volumenanteils von Phasen durch
évaluation des microphotographies Auswertung von Mikrogefügeaufnahmen
This European Standard was approved by CEN on 19 June 2009.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 623-5:2009: E
worldwide for CEN national Members.

Contents
page
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 5
4 Apparatus . 5
4.1 Sectioning equipment . 5
4.2 Mounting equipment. 5
4.3 Grinding and polishing equipment . 5
4.4 Microscope . 5
4.5 Transparent grid . 5
5 Test piece preparation . 6
5.1 Sampling . 6
5.2 Cutting . 6
5.3 Mounting . 6
5.4 Grinding and polishing . 6
5.5 Etching . 6
6 Photomicrography . 7
6.1 General aspects . 7
6.2 Inspection . 7
6.3 Number of micrographs . 7
6.4 Optical microscopy. 7
6.5 Scanning electron microscopy (SEM) . 7
7 Measurement of micrographs . 8
8 Calculation of results . 8
9 Interferences and uncertainties . 9
10 Test report . 9
Annex A (informative)  Grinding and polishing procedures . 11
Annex B (informative)  Etching procedures . 13
Annex C (informative)  Use of automatic image analysis (AIA) . 14
C.1 Background . 14
C.2 Analysis techniques . 14
C.3 Micrograph requirements . 14
C.4 Calibration . 14
Annex D (informative)  Setting Köhler illumination in an optical microscope . 15
D.1 Purpose . 15
D.2 Definition . 15
D.3 Setting up for Köhler illumination . 15
Annex E (informative)  Round robin verification of this procedure . 16
Annex F (informative)  Results sheet . 17
Bibliography . 18

Foreword
This document (EN 623-5:2009) has been prepared by Technical Committee CEN/TC 184 “Advanced technical
ceramics”, the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an identical text or
by endorsement, at the latest by January 2010, and conflicting national standards shall be withdrawn at the latest
by January 2010.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights.
CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes ENV 623-5:2002.
EN 623 consists of five parts, under the general title "Advanced technical ceramics - Monolithic ceramics - General and
textural properties":
 Part 1: Determination of the presence of defects by dye penetration
 Part 2: Determination of density and porosity
 Part 3: Determination of grain size and size distribution (characterized by the Linear Intercept Method)
 Part 4: Determination of surface roughness
 Part 5: Determination of phase volume fraction by evaluation of micrographs
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden,
Switzerland and the United Kingdom.
1 Scope
This part of EN 623 specifies a manual method of making measurements for the determination of volume fraction of
major phases in advanced technical ceramics using micrographs of polished and etched sections, overlaying a square
grid of lines, and counting the number of intersections lying over each phase.
NOTE 1 This method assumes that the true phase volume fractions are equivalent to area fractions on a randomly cut cross-
section according to stereological principles.
NOTE 2 Guidelines for polishing and etching of advanced technical ceramics can be found in Annexes A and B.
The method applies to ceramics with one or more distinct secondary phases, such as found in Al O /ZrO , Si/SiC,or
2 3 2
Al O /SiC .
2 3 w
If the test material contains discrete pores, these can be treated as a secondary phase for the purpose of this method
provided that there is no evidence of grain pluck-out during polishing being confused with genuine pores.
NOTE 3 If the material contains more than about 20 % porosity there is a strong risk that the microstructure will be damaged
during the polishing process, and measurement of volume fraction of pores may become misleading.
Secondary phase volume fractions or porosity present at levels of less than 0,05 are subject to considerable error and
potential scatter in results. A larger number of micrographs than the minimum of three is normally needed to improve
the consistency and accuracy of the results.
NOTE 4 Many ceramics contain small amounts of secondary glassy phases. In order to make a reasonable estimate of
glassy phase content, the glass material between crystalline grains should be readily observable, and thus should be at least
0,5 µm in width. The method in this European Standard is not considered appropriate for narrow glassy films around grains.
This method assumes that the selected regions of a prepared cross-section are statistically representative of the whole
sampled section.
NOTE 5 Microstructures are seldom homogeneous, and the phase contents can vary from micrograph to micrograph. It is
essential to survey a sufficiently wide area of the prepared section to ensure that those areas selected for evaluation are
representative, and do not contain eye-catching irregularities.
Some users of this European Standard can wish to apply automatic or semiautomatic image analysis to micrographs or
directly captured microstructural images. This is currently outside the scope of this European Standard, but some
guidelines are given in Annex C.
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 1006, Advanced technical ceramics - Monolithic ceramics - Guidance on the selection of test pieces for the
evaluation of properties
EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (ISO/IEC
17025:2005)
3 Terms and definitions
For the purposes of this part of EN 623, the following terms and definitions apply.
3.1
phase volume fraction
volume occupied by a distinct, identifiable phase present in a material expressed as a fraction of the whole
3.2
secondary phase
one or more distinct identifiable phases other than a primary crystalline phase in a material
NOTE A secondary phase can be in the form of discrete grains, or as a continuous phase surrounding some or all the
major phase grains. For the purposes of this European Standard, porosity may be treated as a secondary phase.
4 Apparatus
4.1 Sectioning equipment
A suitable diamond-bladed cut-off saw to prepare the initial section for investigation. The saw shall be metal bonded
with a diamond grit size of 125 µm to 150 µm and shall be cooled.
NOTE This grit size is designated D151 according to ISO 6106, see [1].
4.2 Mounting equipment
Suitable metallurgical mounting equipment and media for providing firm gripping of the test piece for polishing.
4.3 Grinding and polishing equipment
Suitable grinding and polishing equipment, employing diamond abrasive media.
NOTE A sequence of abrasives and techniques recommended for polishing are given in Annex A.
4.4 Microscope
An optical or scanning electron microscope with photomicrographic facilities.
NOTE Although the true magnification of the image is unimportant for making the measurement of volume fraction, it is
advised that a reference graticule may be used to determine magnification in an optical microscope, or a reference grid or latex
spheres may be used for calibration of magnification in a scanning electron microscope, and as a check on the homogeneity of
magnification across the field of view.
An optical microscope is additionally required for assessing polishing (see 5.4).
4.5 Transparent grid
Transparent square grid on, e.g. acetate film, and with line thickness not exceeding 0,1 mm.
NOTE 1 The grid spacing selected is not critical, but may conveniently be between 3 mm and 15 mm to minimise eyestrain.
However, it is necessary that consideration of the requirements of 6.3 is taken into account.
NOTE 2 A suitable grid may be prepared as a computer plot with sufficient accuracy of line spacing for the purposes of this
European Standard.
5 Test piece preparation
5.1 Sampling
The test pieces shall be sampled in accordance with the guidelines given in EN 1006, and subject to agreement
between parties.
NOTE Depending on the objectives of performing the measurement, it is desirable to maintain knowledge of the positions
within components or test pieces from which sections are prepared.
5.2 Cutting
The required section of test-piece shall be cut using the diamond saw (see 4.1).
NOTE For routine inspection of materials, a small area of side no more than 10 mm is normally adequate as the section to
be polished.
5.3 Mounting
Mount the test piece using an appropriate mounting medium. If the ceramic is suspected to have significant open
porosity in some regions (see Clause 1) it is advisable to vacuum impregnate the test piece with liquid mounting resin
before encapsulating as this will provide some support during grinding and polishing.
NOTE It is not essential to encapsulate the test piece. For example, it could be affixed to a metal holder. However,
encapsulation in a polymer-based medium allows easy gripping and handling, especially of small irregularly shaped test pieces
and of weak friable test pieces. The method of mounting selected should take into account the etching procedure to be used;
see Annex B.
5.4 Grinding and polishing
Grind and polish the surface of the test piece. Care should be taken to ensure that grinding produces a planar surface
with a minimum of damage. Employ successively smaller grit sizes, at each stage removing the damage from the
previous stage until there is no change in appearance when examined by an optical microscope (see 4.4) at high
magnification. At least 90 % of the test piece area shall be free from optically visible scratches, or other damage
introduced by polishing, which will interfere with the determination. In particular, discrete secondary phases may be
plucked out from the surface giving the appearance of pores. This shall be avoided.
NOTE Care should be taken in choosing the sequence of grits and lap types. It is impossible within the scope of this part of
EN 623 to make specific recommendations for all types of material. The general principle to be adopted is the minimisation of
subsurface damage, and its removal by progressively finer grits whilst retaining a flat surface. Some guidelines on polishing are
given in Annex A.
5.5 Etching
When a good quality polished surface has been achieved, the test piece shall be etched if necessary to reveal the
individual phases. Any suitable technique shall be used, subject to agreement between parties.
NOTE 1 Some general guidelines recommending etching procedures for various commonly available advanced technical
ceramics are given in Annex B.
NOTE 2 For optical evaluation, it is usually necessary to etch oxide materials in such a way that the individual phases are
distinguished by having different contrast levels. For evaluation by scanning electron microscopy (SEM), it may not be
necessary to etch if a backscattered electron detector is used which has adequate resolution of net atomic number difference
between the phases such that contrast is generated. If a secondary electron detector is used, it will usually be necessary to etch
to produce topographic contrast unless the atomic number difference between the phases is large.
6 Photomicrography
6.1 General aspects
If it suspected that the average grain size of each phase or the widths of continuous glassy phases between grains is
less than 2 µm, it will be necessary to prepare the test piece for SEM. Between 2 µm and 4 µm either SEM or optical
microscopy may be used. Otherwise, optical microscopy will normally be adequate.
It is important to achieve sufficient contrast between phases in order to identify individual grains clearly and
unambiguously.
6.2 Inspection
Inspect the sampled cross-section in the microscope. If the microstructure appears homogeneous, prepare
micrographs from randomly selected areas. If inhomogeneity of microstructure is suspected, select representative
areas of relevance for measurement.
6.3 Number of micrographs
At least three micrographs shall be prepared at a magnification sufficient to identify clearly all the phases to be counted.
In addition, at least 100 features in total of any given type shall be present to be counted in the set of micrographs.
NOTE For a nominally homogeneous material, it may be sufficient to use a small number of micrographs analysed with a
small grid spacing, but for an inhomogeneous material, results representative of the average for the sampled section can be
prepared reliably only by selecting a large number of micrographs of different areas, with less intensive counting from a larger
grid.
6.4 Optical microscopy
Set up Köhler illumination in the microscope.
NOTE Guidance on setting Köhler illumination conditions is given in Annex D.
Examine the test piece at a magnification sufficient to resolve the individual grains clearly. If the contrast obtained is
insufficient, e.g. in white or translucent materials, apply a suitable thin metallic coating by evaporation or sputtering.
Prepare micrographs of at least three different randomly selected areas of the test-piece surface, taking into account
the apparent homogeneity of the microstructure (see 6.2). As a guideline, the average size of discrete phase area to be
counted should appear typically at least 3 mm across. If the total number of individual grains of any one phase to be
counted in any one set of micrographs is less than one hundred, prepare more micrographs. Micrographs should be
typically of a size (100 x 75) mm, but may with advantage be enlarged later to aid evaluation.
6.5 Scanning electron microscopy (SEM)
Mount the test piece on the test piece holder of the microscope. If the test piece is not electrically conducting, apply a
thin evaporated or sputtered conductive coating. Insert the test-piece in the microscope, ensuring that the surface to be
characterised is normal to the electron beam to within 5°.
NOTE 1 This ensures that the image does not suffer from excessive distortion or loss of focus due to the angle of viewing.
Prepare micrographs at a suitable magnification (see 6.4) from at least three different randomly selected areas of the
test piece, using either secondary electron imaging or backscattered electron imaging.
NOTE 2 Although the contrast between phases can be enhanced using backscattered electron imaging, a noisier image than
in secondary electron imaging may result and may render the boundaries between contrasting phases indistinct. It can be
helpful to use secondary electron images for counting the phase proportions, but backscattered images to aid identification of
each phase.
If the number of grains of the phase to be counted is less than 100 in total over all the micrographs, increase the
number of areas photographed. Micrographs should typically be of a size (100 x 75) mm, but may with advantage be
enlarged later to aid evaluation.
NOTE 3 It is possible that the photographic screen in the microscope will not have constant magnification at all points. A
square grid makes a suitable reference for ascertaining the degree of distortion in the screen, since it is easy to detect
distortions of the grid. For the purposes of this test method, distortions of typically up to 5 % may be acceptable provided that
the phases being counted are distributed homogeneously across the entire area of the micrograph.
7 Measurement of micrographs
If desirable, enlarge the photomicrograph to a size suitable for easier observation of the features. Examine the
dimensions of the smallest features to be counted. Select a suitable grid spacing and prepare a square grid (see 4.5,
6.3 and comments in Clause 9) such that the g
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