M/076 - Advanced ceramics

Popravek k standardu SIST-TP CEN/TR 13233:2007
This Technical Report defines the symbols to be used to represent physical, mechanical and thermal characteristics, as determined by methods described in relevant CEN publications, for advanced technical ceramics, including ceramic matrix composites. It is a guide for writing the symbols of quantities of these materials to avoid confusion in reporting measurements and characteristics of products. Where possible, the definitions are in accordance with the relevant parts of ISO 31 and ISO 80000. In addition the symbols used in undertaking measurements of these characteristics are also defined.

TC - Table 3 - Small editorial corrections in the English and French versions

This part of EN 12923 specifies guidelines to be employed when undertaking corrosion tests on advanced technical ceramics. The mechanisms of chemical attack on advanced ceramics are widely varied and depend on the chemical and phase composition and the phase morphology of the material, as well as the corrosive conditions imposed. For any particular engineering application it is usually necessary to model expected conditions of use in order to obtain quantitative data on the ability to withstand the proposed end-use conditions.
This European Standard is not restricted to specific material types, nor does it prescribe particular test conditions or a test duration. The actual testing requirements might be very specific, for example, in order to investigate the suitability of a range of materials for a given application in which certain specified conditions occur. This European Standard provides recommended methods for undertaking the assessment of the effect of corrosion and provides guidance on practical issues related to undertaking the tests.

This Technical Report defines the symbols to be used to represent physical, mechanical and thermal characteristics, as determined by methods described in relevant CEN publications, for advanced technical ceramics, including ceramic matrix composites. It is a guide for writing the symbols of quantities of these materials to avoid confusion in reporting measurements and characteristics of products.
Where possible, the definitions are in accordance with the relevant parts of ISO 31 and ISO 80000. In addition the symbols used in undertaking measurements of these characteristics are also defined.

This part of EN 843 specifies a method for statistical analysis of ceramic strength data in terms of a two-parameter Weibull distribution using a maximum likelihood estimation technique. It assumes that the data set has been obtained from a series of tests under nominally identical conditions.
NOTE 1   In principle, Weibull analysis is considered to be strictly valid for the case of linear elastic fracture behaviour to the point of failure, i.e. for a perfectly brittle material, and under conditions in which strength limiting flaws do not interact and in which there is only a single strength-limiting flaw population.
If subcritical crack growth or creep deformation preceding fracture occurs, Weibull analysis can still be applied if the results fit a Weibull distribution, but numerical parameters may change depending on the magnitude of these effects. Since it is impossible to be certain of the degree to which subcritical crack growth or creep deformation has occurred, this European Standard permits the analysis of the general situation where crack growth or creep may have occurred, provided that it is recognized that the parameters derived from the analysis may not be the same as those derived from data with no subcritical crack growth or creep.
NOTE 2   This European Standard employs the same calculation procedures as method A of ISO 20501:2003, but does not provide a method for dealing with censored data (method B of ISO 20501).

This Technical Report defines the symbols to be used to represent physical, mechanical and thermal characteristics, as determined by methods described in relevant CEN publications, for advanced technical ceramics, including ceramic matrix composites. It is a guide for writing the symbols of quantities of these materials to avoid confusion in reporting measurements and characteristics of products.
Where possible, the definitions are in accordance with the relevant parts of ISO 31 and ISO 80000. In addition the symbols used in undertaking measurements of these characteristics are also defined.

This European Prestandard specifies a method for the routine qualitative and quantitative determination of the crystalline phases (monoclinic, tetragonal and cubic) present in zirconia powders using X-ray powder diffraction.

Specifies methods for the determination of calcium, magnesium, iron and aluminium, using flame atomic absorption spectroscopy (FAAS), or inductively coupled plasma atomic emission spectroscopy (ICP-AES).

This part of EN 12923 specifies guidelines to be employed when undertaking corrosion tests on advanced technical ceramics. The mechanisms of chemical attack on advanced ceramics are widely varied and depend on the chemical and phase composition and the phase morphology of the material, as well as the corrosive conditions imposed. For any particular engineering application it is usually necessary to model expected conditions of use in order to obtain quantitative data on the ability to withstand the proposed end-use conditions.
This European Standard is not restricted to specific material types, nor does it prescribe particular test conditions or a test duration. The actual testing requirements might be very specific, for example, in order to investigate the suitability of a range of materials for a given application in which certain specified conditions occur. This European Standard provides recommended methods for undertaking the assessment of the effect of corrosion and provides guidance on practical issues related to undertaking the tests.

This part of EN 843 specifies a method for statistical analysis of ceramic strength data in terms of a two-parameter Weibull distribution using a maximum likelihood estimation technique. It assumes that the data set has been obtained from a series of tests under nominally identical conditions.
NOTE 1   In principle, Weibull analysis is considered to be strictly valid for the case of linear elastic fracture behaviour to the point of failure, i.e. for a perfectly brittle material, and under conditions in which strength limiting flaws do not interact and in which there is only a single strength-limiting flaw population.
If subcritical crack growth or creep deformation preceding fracture occurs, Weibull analysis can still be applied if the results fit a Weibull distribution, but numerical parameters may change depending on the magnitude of these effects. Since it is impossible to be certain of the degree to which subcritical crack growth or creep deformation has occurred, this European Standard permits the analysis of the general situation where crack growth or creep may have occurred, provided that it is recognized that the parameters derived from the analysis may not be the same as those derived from data with no subcritical crack growth or creep.
NOTE 2   This European Standard employs the same calculation procedures as method A of ISO 20501:2003, but does not provide a method for dealing with censored data (method B of ISO 20501).

TThis document specifies the conditions for determination of the flexural strength of ceramic matrix composite materials with continuous fibre reinforcement under three-point or four-point bending for temperatures up to 2 000 °C under vacuum or a gas atmosphere which is inert to the material under test.
NOTE 1   The use of these environments is aimed at avoiding changes of the material affecting its flexural strength caused by chemical reaction with its environment during the test.
This European document applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 < x L 3), loaded along one principal axis of reinforcement.
NOTE 2   The method outlined in this document should not be used to obtain values of flexural strength for design purposes.

TC agrees to change the ENV into new deliverable CEN/TS (CC/011212)

This European Standard specifies the conditions for the determination of the in-plane shear properties at ambient temperature of ceramic matrix composite materials with continuous fibre reinforcement.
This European Standard applies to ceramic matrix composites with a continuous fibre reinforcement, bi-directional (2D) and tri-directional (xD, with 2 < x < 3).

This document specifies the conditions for determination of the inter-laminar shear strength of ceramic matrix composite materials with continuous fibre reinforcement for temperatures up to 2 000 °C under a vacuum, or a gas atmosphere, which is inert to the material under test, by loading of notched specimens in compression.
NOTE 1   The use of a vacuum or a gas atmosphere is aimed at avoiding changes of the material to be tested due to chemical reaction with its environment during the test.
This document applies to all ceramic matrix composites with continuous fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 < x < 3), loaded along one principal axis of reinforcement.
NOTE 2   Care should be exercised in interpreting the results of the test method to obtain absolute values of the inter-laminar shear strength of ceramic matrix composites for design purposes.
.

TThis document specifies the conditions for determination of the flexural strength of ceramic matrix composite materials with continuous fibre reinforcement under three-point or four-point bending for temperatures up to 2 000 °C under vacuum or a gas atmosphere which is inert to the material under test.
NOTE 1   The use of these environments is aimed at avoiding changes of the material affecting its flexural strength caused by chemical reaction with its environment during the test.
This European document applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 < x £ 3), loaded along one principal axis of reinforcement.
NOTE 2   The method outlined in this document should not be used to obtain values of flexural strength for design purposes.

This European Standard specifies the conditions for the determination of the in-plane shear properties at ambient temperature of ceramic matrix composite materials with continuous fibre reinforcement.
This European Standard applies to ceramic matrix composites with a continuous fibre reinforcement, bi-directional (2D) and tri-directional (xD, with 2 < x < 3).

ISO 15732:2003 describes a test method for the determination of fracture toughness of monolithic ceramic materials at room temperature by the Single-Edge-Precracked-Beam (SEPB) method.
This International Standard is intended for use with monolithic ceramics and whisker- or particulate-reinforced ceramics which are regarded as macroscopically homogeneous. It does not include continuous-fiber-reinforced ceramic composites.
ISO 15732:2003 is for material development, material comparison, quality assurance, characterization, reliability and design data generation.
Fracture toughness values determined with other test methods cannot be interchanged with KIpb as defined in this International Standard, and may not be interchangeable with each other.

This document specifies the conditions for determination of the inter-laminar shear strength of ceramic matrix composite materials with continuous fibre reinforcement for temperatures up to 2 000 °C under a vacuum, or a gas atmosphere, which is inert to the material under test, by loading of notched specimens in compression.
NOTE 1   The use of a vacuum or a gas atmosphere is aimed at avoiding changes of the material to be tested due to chemical reaction with its environment during the test.
This document applies to all ceramic matrix composites with continuous fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 < x < 3), loaded along one principal axis of reinforcement.
NOTE 2   Care should be exercised in interpreting the results of the test method to obtain absolute values of the inter-laminar shear strength of ceramic matrix composites for design purposes.
.

1.1   This part of prCEN/TS 14425 provides information on the comparative value, and guidance on the selection, of test methods for determining the apparent fracture toughness of monolithic advanced technical ceramics. For the purposes of this standard, the term monolithic includes particle, platelet and whisker reinforced advanced technical ceramics which can be regarded as macroscopically homogeneous. It does not include long-fibre reinforced ceramics.
1.2   Reference is made in this part of prCEN/TS 14425 to specific test methods described in other parts of this Technical Specification.

2004-03 TCsec Resubmitted the document for publication via e-Trans

This document describes a method for the determination of the thermal conductivity of ceramic matrix composites with continuous fibre reinforcement. This method applies to all ceramic matrix composites with a fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 < x  3) as defined in ENV 13233, submitted to a heat flux along one principal axis of anisotropy.
The experimental conditions are such that the material behaves in an homogeneous manner for each of its axis of anisotropy and that the heat transfer occurs only by thermal conduction. The method is applicable to materials which are physically and chemically stable during the measurement.
Contrary to other methods of direct measurement which permit only to determine a value of the thermal conductivity averaged over an interval of temperature, the method described in this document, based on an adequate exploitation of the temperature record, allows to determine with a good accuracy the thermal conductivity at a defined temperature. This is more interesting since the variation of the thermal conductivity with the temperature is non-linear, which is generally the case for CMC's.
NOTE   It is also possible to calculate the conductivity of CMC's by an indirect method using the following equation:
 = a   pb  Cp
where
   is the thermal conductivity;
a   is the thermal diffusivity;
pb   is the bulk density;
Cp   is the specific heat capacity.

This standard specifies the conditions for determination of the flexural strength of ceramic matrix composite materials with continuous fibre reinforcement under three-point or four-point bending for temperatures up to 1700°C in air at atmospheric pressure. This Prestandard applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2

1.1   This part of prCEN/TS 14425 provides information on the comparative value, and guidance on the selection, of test methods for determining the apparent fracture toughness of monolithic advanced technical ceramics. For the purposes of this standard, the term monolithic includes particle, platelet and whisker reinforced advanced technical ceramics which can be regarded as macroscopically homogeneous. It does not include long-fibre reinforced ceramics.
1.2   Reference is made in this part of prCEN/TS 14425 to specific test methods described in other parts of this Technical Specification.

This standard specifies the conditions for determination of the flexural strength of ceramic matrix composite materials with continuous fibre reinforcement under three-point or four-point bending for temperatures up to 1700°C in air at atmospheric pressure. This Prestandard applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2

This European Prestandard specifies a method for the routine qualitative and quantitative determination of the crystalline phases (monoclinic, tetragonal and cubic) present in zirconia powders using X-ray powder diffraction.

This European Prestandard specifies methods for the determination of calcium, magnesium, iron, and aluminium, using flame atomic absorption spectroscopy (FAAS), or inductively coupled plasma atomic emission spectroscopy (ICP-AES).
The methods are applicable to the concentration ranges given in clause 3.

This part of EN 725 specifies methods for the determination of the levels of silicon, aluminium, titanium, iron, calcium, magnesium, potassium, sodium, yttrium, hafnium, cerium and strontium using flame atomic absorption spectrometry (FAAS) and inductively coupled plasma atomic emission spectrometry (ICP - AES).  These methods are applicable to the concentration ranges given in clause 3, expressed as oxides.

This Part of ENV 12923 describes a simple oxidation test for advanced technical ceramics. The test is designed to give an assessment of the mass and dimensional changes of test pieces following oxidation at high temperature in an oxidizing atmosphere, and to assess whether oxidation has a significant effect on the subsequent strength, either at room temperature or at elevated temperatures.
NOTE 1 This test method does not allow definition of other mechanical performance changes resulting from high-temperature exposure, such as changes in susceptibility to subcritical crack growth, creep behaviour, migration of secondary constituents, etc.
NOTE 2 This test method does not cover the additional effects of other corrodents in the ambient atmosphere, such as salt vapours, reducing or corrosive gases, and other contaminants. This method also does not cover tests at pressures other than ambient atmospheric pressure.
NOTE 3 An interlaboratory evaluation of the procedure given in this standard is summarised in annex A.

This part of EN 725 specifies methods for the determination of the levels of silicon, aluminium, titanium, iron, calcium, magnesium, potassium, sodium, yttrium, hafnium, cerium and strontium using flame atomic absorption spectrometry (FAAS) and inductively coupled plasma atomic emission spectrometry (ICP - AES).  These methods are applicable to the concentration ranges given in clause 3, expressed as oxides.

This Part of ENV 12923 describes a simple oxidation test for advanced technical ceramics. The test is designed to give an assessment of the mass and dimensional changes of test pieces following oxidation at high temperature in an oxidizing atmosphere, and to assess whether oxidation has a significant effect on the subsequent strength, either at room temperature or at elevated temperatures.
NOTE 1 This test method does not allow definition of other mechanical performance changes resulting from high-temperature exposure, such as changes in susceptibility to subcritical crack growth, creep behaviour, migration of secondary constituents, etc.
NOTE 2 This test method does not cover the additional effects of other corrodents in the ambient atmosphere, such as salt vapours, reducing or corrosive gases, and other contaminants. This method also does not cover tests at pressures other than ambient atmospheric pressure.
NOTE 3 An interlaboratory evaluation of the procedure given in this standard is summarised in annex A.

This European Prestandard (ENV) specifies a method for the determination of the flowability behaviour of ceramic granules by means of a calibrated funnel.

This European Standard specifies the conditions for determination of compression properties of ceramic matrix composite materials with continuous fibre reinforcement for temperatures up to 2 000 °C under vacuum or a gas atmosphere which is inert to the material under test.
NOTE   The use of these environments is aimed at avoiding changes of the material to be tested due to chemical reaction with its environment during the test.
This European Standard applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 < x * 3), loaded along one principal axis of reinforcement.
Two types of compression are distinguished:
a)   compression between platens;
b)   compression using grips.

This document specifies the conditions for determination of tensile properties of ceramic matrix composite materials with continuous fibre reinforcement for temperatures up to 1 700 °C in air at atmospheric pressure.
This document applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1D), bi directional (2D), and tri-directional (xD, with 2 < x = 3), loaded along one principal axis of reinforcement.
NOTE 1   In most cases, ceramic matrix composites to be used at high temperature in air are coated with an anti-oxidation coating.
NOTE 2   The purpose of this document is to determine the tensile properties of a material when it is placed under an oxidizing environment but not to measure material oxidation.

This document specifies the conditions for determination of tensile properties of ceramic matrix composite materials with continuous fibre reinforcement for temperatures up to 2 000 °C under vacuum or a gas atmosphere which is inert to the material under test.
NOTE   The use of these environments is aimed at avoiding changes of the material to be tested due to chemical reaction with its environment during the test.
This document applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 < x L 3), loaded along one principal axis of reinforcement.

This European Standard EN 12291 specifies the conditions for determination of compression properties of ceramic matrix composite materials with continuous fibre reinforcement for temperatures up to 1 700 °C in air at atmospheric pressure.
This European Standard applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 < x < 3), loaded along one principal axis of reinforcement.
NOTE 1   In most cases, ceramic matrix composites to be used at high temperature in air are coated with an anti oxidation coating.
NOTE 2   The purpose of this European standard is to determine the compression properties of a material when it is placed under an oxidizing environment but not to measure material oxidation.
Two cases are distinguished:
a) compression between platens;
b) compression using grips.

This European Standard specifies the conditions for determination of compression properties of ceramic matrix composite materials with continuous fibre reinforcement for temperatures up to 2 000 °C under vacuum or a gas atmosphere which is inert to the material under test.
NOTE   The use of these environments is aimed at avoiding changes of the material to be tested due to chemical reaction with its environment during the test.
This European Standard applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 < x * 3), loaded along one principal axis of reinforcement.
Two types of compression are distinguished:
a)   compression between platens;
b)   compression using grips.

This European Standard EN 12291 specifies the conditions for determination of compression properties of ceramic matrix composite materials with continuous fibre reinforcement for temperatures up to 1 700 °C in air at atmospheric pressure.
This European Standard applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 < x < 3), loaded along one principal axis of reinforcement.
NOTE 1   In most cases, ceramic matrix composites to be used at high temperature in air are coated with an anti oxidation coating.
NOTE 2   The purpose of this European standard is to determine the compression properties of a material when it is placed under an oxidizing environment but not to measure material oxidation.
Two cases are distinguished:
a) compression between platens;
b) compression using grips.

This European Prestandard (ENV) specifies a method for the determination of the flowability behaviour of ceramic granules by means of a calibrated funnel.

This document specifies the conditions for determination of tensile properties of ceramic matrix composite materials with continuous fibre reinforcement for temperatures up to 1 700 °C in air at atmospheric pressure.
This document applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1D), bi directional (2D), and tri-directional (xD, with 2 < x = 3), loaded along one principal axis of reinforcement.
NOTE 1   In most cases, ceramic matrix composites to be used at high temperature in air are coated with an anti-oxidation coating.
NOTE 2   The purpose of this document is to determine the tensile properties of a material when it is placed under an oxidizing environment but not to measure material oxidation.

This document specifies the conditions for determination of tensile properties of ceramic matrix composite materials with continuous fibre reinforcement for temperatures up to 2 000 °C under vacuum or a gas atmosphere which is inert to the material under test.
NOTE   The use of these environments is aimed at avoiding changes of the material to be tested due to chemical reaction with its environment during the test.
This document applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1D), bidirectional (2D), and tridirectional (xD, with 2 < x £ 3), loaded along one principal axis of reinforcement.

This part of CEN/TS 14425 provides a test method for fracture toughness determination based on the chevron-notch method. For the purposes of this standard, the term monolithic includes particle and whisker reinforced advanced technical ceramics which can be regarded as macroscopically homogeneous. It does not included long-fibre reinforced ceramics.

This part of CEN/TS 14425 provides a test method for fracture toughness determination based on the chevron-notch method. For the purposes of this standard, the term monolithic includes particle and whisker reinforced advanced technical ceramics which can be regarded as macroscopically homogeneous. It does not included long-fibre reinforced ceramics.

This part of ENV 1007 specifies the conditions for the determination of the distribution of strength and rupture strain of ceramic filaments within a multifilament tow at room temperature by performing a single tensile test on a multifilament tow. This prestandard applies to tows of continuous ceramic filaments which are assumed to act freely and idependently under loading, and behave linearly elastic up to failure.

This part of ENV 1007 specifies the conditions for the determination of the distribution of strength and rupture strain of ceramic filaments within a multifilament tow at room temperature by performing a single tensile test on a multifilament tow. This prestandard applies to tows of continuous ceramic filaments which are assumed to act freely and idependently under loading, and behave linearly elastic up to failure.

This European Prestandard is a vocabulary which provides a list of terms and associated definitions which are typically used for advanced technical ceramic materials, products, applications, properties and processes. The document contains, in separate lists, those abbreviations which have found general acceptance in scientific and technical literature; they are given together with the corresponding terms and definitions or descriptions.
NOTE 1  This prestandard does not include terms which, though used in the field of advanced technical ceramics, are of a more general nature and are also well known in other fields of technology.
NOTE 2  A list of some European Standards, European Prestandards and Draft European Standards of CEN Technical Committee 184 "Advanced technical ceramics" containing terms defined in this European Prestandard, is given in the Bibliography.

This European Prestandard is a vocabulary which provides a list of terms and associated definitions which are typically used for advanced technical ceramic materials, products, applications, properties and processes. The document contains, in separate lists, those abbreviations which have found general acceptance in scientific and technical literature; they are given together with the corresponding terms and definitions or descriptions.
NOTE 1  This prestandard does not include terms which, though used in the field of advanced technical ceramics, are of a more general nature and are also well known in other fields of technology.
NOTE 2  A list of some European Standards, European Prestandards and Draft European Standards of CEN Technical Committee 184 "Advanced technical ceramics" containing terms defined in this European Prestandard, is given in the Bibliography.

This European Prestandard 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 Al2O3/ZrO2, Si/SiC, or Al2O3/SiCw.
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 Prestandard is not considered appropriate for narrow glassy films around grains.

This Technical Specification contains guidelines to be adopted when evaluating the appearance of the
fracture surface of an advanced technical ceramic. The purpose in undertaking this procedure can be
various, for example, for material development or quality assessment, to identify normal or abnormal
causes of failure, or as a design aid.
NOTE Not all advanced technical ceramics are amenable to fractography. In particular, coarse-grained ceramics
can show such rough surfaces that identifying the fracture origin may be impossible. Similarly, porous materials,
especially those of a granular nature, tend not to fracture in a continuous manner, making analysis difficult.

This Technical Specification contains guidelines to be adopted when evaluating the appearance of the
fracture surface of an advanced technical ceramic. The purpose in undertaking this procedure can be
various, for example, for material development or quality assessment, to identify normal or abnormal
causes of failure, or as a design aid.
NOTE Not all advanced technical ceramics are amenable to fractography. In particular, coarse-grained ceramics
can show such rough surfaces that identifying the fracture origin may be impossible. Similarly, porous materials,
especially those of a granular nature, tend not to fracture in a continuous manner, making analysis difficult.

This part of ENV 820 describes methods for determining the elastic moduli, specifically Young's modulus, shear modulus and Poisson's ratio, of advanced monolithic technical ceramics at temperatures above room temperature. The Technical Specification prescribes three alternative methods for determining some or all of these three parameters:
A   The determination of Young's modulus by static flexure of a thin beam in three- or four-point bending.
B   The determination of Young's modulus by forced longitudinal resonance, or Young's modulus, shear modulus and Poisson's ratio by forced flexural and torsional resonance, of a thin beam.
C   The determination of Young's modulus from the fundamental natural frequency of a struck bar (impulse excitation method).
This Technical Specification extends the above-defined room-temperature methods described in ENV 843-2 to elevated temperatures. All the test methods assume the use of homogeneous test pieces of linear elastic materials. The test assumes that the test piece has isotropic elastic properties. At high porosity levels all of the methods can become inappropriate. The maximum grain size (see EN 623-3), excluding deliberately added whiskers, should be less than 10% of the minimum dimension of the test piece.