EN IEC 60413:2026
(Main)Test procedures for determining physical properties of brush materials
General Information
- Abstract
IEC 60413:2026 concerns graphite-based grades that are used for sliding electrical contacts, such as carbon brushes or pantograph strips. By extension, it is possible to apply the test procedures of this document to all electrical sliding contacts for electrical transmission appliances and to other appliances of graphite-based materials (heat exchangers, bearings, etc.). This document specifies uniformized procedures for determining their following properties: - density and porosity; - resistivity; - flexural strength; - hardness; - ash content. In addition, it provides recommendations on test procedures for other properties: - Mechanical properties: Charpy impact test, compressive strength, tensile strength (Annex B). - Thermal properties: coefficient of thermal expansion, specific heat capacity, thermal conductivity (Annex C). The properties determined by these tests are inherent to the graphite-based materials and it is therefore important to distinguish them from performance characteristics in operation on electrical equipment (carbon brush in an electrical rotating machine, contact strips on a pantograph, etc.). Since these materials are generally brittle, porous materials, it is reasonable that their properties vary much more than the same properties in metals. Some test methods are suitable for use in production quality control (routine tests), others only for more thorough investigations, using precise laboratory techniques (see Annex A). WARNING — The use of this document can involve hazardous substances, operations and equipment. It does not purport to address all of the safety or environmental problems associated with its use. It is the responsibility of the user of this document to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. This second edition cancels and replaces the first edition published in 1972. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) Title modified. b) Addition of definitions in Clause 3. c) Clause 5 on test specimen: Nomenclature and addition of the different types of test specimen, specification on their dimensions, tolerances and preparation. d) Improvement of test procedures of the properties already disclosed in the previous edition (Clause 6 to Clause 11). e) Separation of apparent density and apparent porosity (respectively Clause 6 and Clause 10). f) Resistivity (Clause 7): Addition of the eddy current method. g) Rebound hardness (Clause 9): Addition of a new model of scleroscope and addition of Leeb method, as a possible alternative to the traditional scleroscope method. h) Common elements of the test report in a dedicated Clause 12. i) Addition of Annex A (normative): introduction of tests categories (serial/type tests), list of properties to be tested for each test category of test according to their purpose. j) Addition of Annex B: test procedures for other mechanical properties than flexural strength and hardness: tensile, compressive and impact strength. k) Addition of Annex C: test procedures for thermal properties (coefficient of linear expansion, specific heat capacity and thermal conductivity). l) Addition of Annex D: supplement to density and porosity. m) Addition of Annex E: recommendations on methods for elements analysis. n) Addition of Annex F: supplem
- Status
- Published
- Publication Date
- 23-Apr-2026
- Technical Committee
- CLC/TC 2 - Rotating machinery
- Drafting Committee
- IEC/TC 2 - IEC_TC_2
- Current Stage
- 6060 - Document made available - Publishing
- Start Date
- 24-Apr-2026
- Due Date
- 31-Jul-2024
- Completion Date
- 24-Apr-2026
Overview
EN IEC 60413:2026 establishes standardized test procedures for determining the physical properties of brush materials, with a specific focus on graphite-based grades used in sliding electrical contacts. These include carbon brushes and pantograph strips commonly found in electrical machines and transmission appliances. The standard is published by the European Committee for Electrotechnical Standardization (CLC) and aligns with the International Electrotechnical Commission (IEC) requirements.
The document defines uniform methods for assessing key physical properties such as density, porosity, resistivity, flexural strength, hardness, and ash content. It also provides guidance for additional mechanical and thermal properties testing. Importantly, EN IEC 60413:2026 serves as a foundational tool for both quality assurance and research, regardless of the specific graphite-based component in use.
Key Topics
Material Scope: Focuses on graphite and carbon-based materials used in electrical sliding contacts (e.g., carbon brushes, pantograph strips). Test procedures are also applicable to similar components like bushings, heat exchangers, and bearings.
Standardized Testing Methods:
- Physical Properties: Density, porosity, resistivity (including eddy current testing), flexural strength, hardness (indentation, Scleroscope, and Leeb methods), and ash content.
- Mechanical Properties (Annex B): Charpy impact, compressive, and tensile strength.
- Thermal Properties (Annex C): Coefficient of thermal expansion, specific heat capacity, and thermal conductivity.
Distinction of Property Types: The standard emphasizes measuring the inherent material properties separately from operational performance in end-use electrical equipment.
Test Categorization: Differentiates between routine quality control procedures and advanced laboratory tests, supporting both manufacturing and research needs.
Recent updates in this edition:
- Expanded definitions and clear specimen preparation guidelines.
- Enhanced test procedures for all major property categories.
- Inclusion of new measurement techniques, alternative hardness testing methods, and detailed reporting requirements.
Applications
EN IEC 60413:2026 has broad relevance in electrical engineering and manufacturing sectors. Practical applications include:
- Production Quality Control: Routine testing of graphite-based sliding contacts during and after manufacturing to ensure consistent quality and conformity with international standards.
- Product Development and Research: Supports the optimization of new brush materials, especially where mechanical or thermal performance is critical.
- Maintenance and Reliability Assessment: Enables service centers and end-users to evaluate aging, wear, and suitability of brush materials in continuous operation environments such as motors, generators, and railway pantographs.
- Cross-industry Utility: Testing methods are suitable for other carbon-based components found in heat exchangers, bearings, and specialized electrical transmission systems.
Related Standards
When working with EN IEC 60413:2026, several other international and European standards may be relevant for a comprehensive test and compliance program:
- IEC 60136: Electrical Insulating Materials - Methods of Test
- IEC 60254: Lead-acid traction batteries - General requirements and methods of test
- IEC 60243: Electric Strength of Insulating Materials
- IEC 60068: Environmental Testing Procedures
- ISO 80000: Quantities and Units (useful for results interpretation and reporting)
- Other CLC and IEC standards specific to rotating electrical machines and material analysis
By following the unified test procedures detailed in EN IEC 60413:2026, laboratories, manufacturers, and quality assurance teams ensure reliable, repeatable, and internationally recognized assessment of the physical properties of graphite-based brush materials, ultimately supporting safety, efficiency, and durability in electrical transmission and rotating machinery.
Relations
- Effective Date
- 28-Apr-2026
- Effective Date
- 28-Apr-2026
- Effective Date
- 28-Apr-2026
- Effective Date
- 28-Apr-2026
- Effective Date
- 28-Apr-2026
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Frequently Asked Questions
EN IEC 60413:2026 is a standard published by CLC. Its full title is "Test procedures for determining physical properties of brush materials". This standard covers: IEC 60413:2026 concerns graphite-based grades that are used for sliding electrical contacts, such as carbon brushes or pantograph strips. By extension, it is possible to apply the test procedures of this document to all electrical sliding contacts for electrical transmission appliances and to other appliances of graphite-based materials (heat exchangers, bearings, etc.). This document specifies uniformized procedures for determining their following properties: - density and porosity; - resistivity; - flexural strength; - hardness; - ash content. In addition, it provides recommendations on test procedures for other properties: - Mechanical properties: Charpy impact test, compressive strength, tensile strength (Annex B). - Thermal properties: coefficient of thermal expansion, specific heat capacity, thermal conductivity (Annex C). The properties determined by these tests are inherent to the graphite-based materials and it is therefore important to distinguish them from performance characteristics in operation on electrical equipment (carbon brush in an electrical rotating machine, contact strips on a pantograph, etc.). Since these materials are generally brittle, porous materials, it is reasonable that their properties vary much more than the same properties in metals. Some test methods are suitable for use in production quality control (routine tests), others only for more thorough investigations, using precise laboratory techniques (see Annex A). WARNING — The use of this document can involve hazardous substances, operations and equipment. It does not purport to address all of the safety or environmental problems associated with its use. It is the responsibility of the user of this document to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. This second edition cancels and replaces the first edition published in 1972. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) Title modified. b) Addition of definitions in Clause 3. c) Clause 5 on test specimen: Nomenclature and addition of the different types of test specimen, specification on their dimensions, tolerances and preparation. d) Improvement of test procedures of the properties already disclosed in the previous edition (Clause 6 to Clause 11). e) Separation of apparent density and apparent porosity (respectively Clause 6 and Clause 10). f) Resistivity (Clause 7): Addition of the eddy current method. g) Rebound hardness (Clause 9): Addition of a new model of scleroscope and addition of Leeb method, as a possible alternative to the traditional scleroscope method. h) Common elements of the test report in a dedicated Clause 12. i) Addition of Annex A (normative): introduction of tests categories (serial/type tests), list of properties to be tested for each test category of test according to their purpose. j) Addition of Annex B: test procedures for other mechanical properties than flexural strength and hardness: tensile, compressive and impact strength. k) Addition of Annex C: test procedures for thermal properties (coefficient of linear expansion, specific heat capacity and thermal conductivity). l) Addition of Annex D: supplement to density and porosity. m) Addition of Annex E: recommendations on methods for elements analysis. n) Addition of Annex F: supplem
IEC 60413:2026 concerns graphite-based grades that are used for sliding electrical contacts, such as carbon brushes or pantograph strips. By extension, it is possible to apply the test procedures of this document to all electrical sliding contacts for electrical transmission appliances and to other appliances of graphite-based materials (heat exchangers, bearings, etc.). This document specifies uniformized procedures for determining their following properties: - density and porosity; - resistivity; - flexural strength; - hardness; - ash content. In addition, it provides recommendations on test procedures for other properties: - Mechanical properties: Charpy impact test, compressive strength, tensile strength (Annex B). - Thermal properties: coefficient of thermal expansion, specific heat capacity, thermal conductivity (Annex C). The properties determined by these tests are inherent to the graphite-based materials and it is therefore important to distinguish them from performance characteristics in operation on electrical equipment (carbon brush in an electrical rotating machine, contact strips on a pantograph, etc.). Since these materials are generally brittle, porous materials, it is reasonable that their properties vary much more than the same properties in metals. Some test methods are suitable for use in production quality control (routine tests), others only for more thorough investigations, using precise laboratory techniques (see Annex A). WARNING — The use of this document can involve hazardous substances, operations and equipment. It does not purport to address all of the safety or environmental problems associated with its use. It is the responsibility of the user of this document to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. This second edition cancels and replaces the first edition published in 1972. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) Title modified. b) Addition of definitions in Clause 3. c) Clause 5 on test specimen: Nomenclature and addition of the different types of test specimen, specification on their dimensions, tolerances and preparation. d) Improvement of test procedures of the properties already disclosed in the previous edition (Clause 6 to Clause 11). e) Separation of apparent density and apparent porosity (respectively Clause 6 and Clause 10). f) Resistivity (Clause 7): Addition of the eddy current method. g) Rebound hardness (Clause 9): Addition of a new model of scleroscope and addition of Leeb method, as a possible alternative to the traditional scleroscope method. h) Common elements of the test report in a dedicated Clause 12. i) Addition of Annex A (normative): introduction of tests categories (serial/type tests), list of properties to be tested for each test category of test according to their purpose. j) Addition of Annex B: test procedures for other mechanical properties than flexural strength and hardness: tensile, compressive and impact strength. k) Addition of Annex C: test procedures for thermal properties (coefficient of linear expansion, specific heat capacity and thermal conductivity). l) Addition of Annex D: supplement to density and porosity. m) Addition of Annex E: recommendations on methods for elements analysis. n) Addition of Annex F: supplem
EN IEC 60413:2026 is classified under the following ICS (International Classification for Standards) categories: 29.160.10 - Components for rotating machines. The ICS classification helps identify the subject area and facilitates finding related standards.
EN IEC 60413:2026 has the following relationships with other standards: It is inter standard links to EN ISO 22007-2:2022, EN ISO 148-1:2016, EN ISO 6508-2:2023, EN IEC 60276:2019, EN ISO 179-1:2023. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
EN IEC 60413:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-2026
Testni postopki za določanje fizikalnih lastnosti materialov ščetk za električne
stroje (IEC 60413:2026)
Test procedures for determining physical properties of brush materials for electrical
machines (IEC 60413:2026)
Prüfverfahren zur Bestimmung der physikalischen Eigenschaften der Werkstoffe von
Kohlebürsten für elektrische Maschinen (IEC 60413:2026)
Méthodes d'essai pour la mesure des propriétés physiques des matières de balais pour
machines électriques (IEC 60413:2026)
Ta slovenski standard je istoveten z: EN IEC 60413:2026
ICS:
29.160.10 Sestavni deli rotacijskih Components for rotating
strojev machines
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN IEC 60413
NORME EUROPÉENNE
EUROPÄISCHE NORM April 2026
ICS 29.160.10
English Version
Test procedures for determining physical properties of brush
materials
(IEC 60413:2026)
Modes opératoires d'essai pour déterminer les propriétés Prüfverfahren zur Bestimmung der physikalischen
physiques des matériaux de balais Eigenschaften der Werkstoffe von Kohlebürsten für
(IEC 60413:2026) elektrische Maschinen
(IEC 60413:2026)
This European Standard was approved by CENELEC on 2026-04-17. CENELEC 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-CENELEC
Management Centre or to any CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60413:2026 E
European foreword
The text of document 2/2286/FDIS, future edition 2 of IEC 60413, prepared by TC 2 "Rotating
machinery" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-04-30
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-04-30
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 60413:2026 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 60773 NOTE Approved as EN IEC 60773
ISO 868 NOTE Approved as EN ISO 868
ISO 2739:2012 NOTE Approved as EN ISO 2739:2012 (not modified)
ISO 6508-1:2023 NOTE Approved as EN ISO 6508-1:2023 (not modified)
ISO 7500-1 NOTE Approved as EN ISO 7500-1
ISO 11357-1:2023 NOTE Approved as EN ISO 11357-1:2023 (not modified)
ISO 11357-4 NOTE Approved as EN ISO 11357-4
ISO 13102:2012 NOTE Approved as EN ISO 13102:2012 (not modified)
ISO 13385-1:2019 NOTE Approved as EN ISO 13385-1:2019 (not modified)
ISO 16859-1:2015 NOTE Approved as EN ISO 16859-1:2015 (not modified)
ISO 16859-3 NOTE Approved as EN ISO 16859-3
ISO 18265:2013 NOTE Approved as EN ISO 18265:2013 (not modified)
ISO 18755:2022 NOTE Approved as EN ISO 18755:2023 (not modified)
ISO 19628:2024 NOTE Approved as EN ISO 19628:2024 (not modified)
ISO 21920-2:2021 NOTE Approved as EN ISO 21920-2:2022 (not modified)
ISO 22007-4:2024 NOTE Approved as EN ISO 22007-4:2024 (not modified)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60276 - Carbon brushes, brush holders, EN IEC 60276 -
commutators and slip-rings - Definitions
and nomenclature
ISO 148-1 - Metallic materials - Charpy pendulum EN ISO 148-1 -
impact test - Part 1: Test method
ISO 179-1 2023 Plastics - Determination of Charpy impact - -
properties - Part 1: Non-instrumented
impact test
ISO 6508-2 - Metallic materials - Rockwell hardness test EN ISO 6508-2 -
- Part 2: Verification and calibration of
testing machines and indenters
ISO 22007-2 2022 Plastics - Determination of thermal EN ISO 22007-2 2022
conductivity and thermal diffusivity - Part 2:
Transient plane heat source (hot disc)
method
IEC 60413 ®
Edition 2.0 2026-03
INTERNATIONAL
STANDARD
Test procedures for determining physical properties of brush materials
ICS 29.160.10 ISBN 978-2-8327-1114-9
IEC 60413:2026-03(en)
IEC 60413:2026 © IEC 2026
CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references . 9
3 Terms, definitions and symbols . 10
4 Symbols . 15
5 Test specimen . 17
5.1 General . 17
5.2 Types of test specimen . 18
5.2.1 General. 18
5.2.2 Type A . 18
5.2.3 Type B . 18
5.2.4 Type C . 19
5.2.5 Type D . 19
5.3 Preparation of test specimens . 19
5.3.1 General. 19
5.3.2 Relation between dimensions and grain direction . 20
5.3.3 Requirements on test specimens . 22
6 Apparent density . 23
6.1 General . 23
6.2 Mass-and-dimensions method . 23
6.2.1 General. 23
6.2.2 Principle of measurement . 23
6.2.3 Test equipment . 23
6.2.4 Test specimen . 24
6.2.5 Test condition . 24
6.2.6 Test procedure . 24
6.2.7 Calculation and report . 24
6.3 Immersion method . 24
6.3.1 General. 24
6.3.2 Principle of measurement . 25
6.3.3 Reagents . 25
6.3.4 Test equipment . 25
6.3.5 Test specimen . 27
6.3.6 Test condition . 27
6.3.7 Procedure of measurement . 28
6.3.8 Calculation and report . 30
7 Resistivity (specific resistance) . 31
7.1 General . 31
7.2 Voltmeter-ammeter method . 31
7.2.1 Principle of measurement . 31
7.2.2 Test equipment . 32
7.2.3 Test specimen . 33
7.2.4 Test conditions . 33
7.2.5 Procedure of measurement . 35
7.2.6 Calculation and report . 35
7.3 Eddy current method . 36
IEC 60413:2026 © IEC 2026
7.3.1 General. 36
7.3.2 Principle of measurement . 36
7.3.3 Test equipment . 36
7.3.4 Test specimen . 37
7.3.5 Test conditions . 37
7.3.6 Procedure of measurement . 37
7.3.7 Calculation and record . 38
8 Flexural strength . 38
8.1 General . 38
8.2 Principle of measurement . 39
8.3 Test equipment. 39
8.3.1 Test machine . 39
8.3.2 Supporting knives . 39
8.3.3 Load knife . 40
8.4 Test specimen . 40
8.5 Test conditions . 42
8.6 Procedure of measurement . 42
8.7 Calculation and report . 43
9 Hardness . 44
9.1 Hardness by indentation . 44
9.1.1 General. 44
9.1.2 Principle . 44
9.1.3 Test equipment . 45
9.1.4 Test specimen . 45
9.1.5 Test conditions . 45
9.1.6 Test procedure . 46
9.1.7 Calculation and report . 48
9.2 Rebound hardness with scleroscope method . 48
9.2.1 General. 48
9.2.2 Principle of measurement . 48
9.2.3 Test equipment . 49
9.2.4 Test specimen . 51
9.2.5 Test condition . 51
9.2.6 Test procedure . 52
9.2.7 Calculation and report . 52
9.3 Rebound hardness with Leeb method . 53
9.3.1 General. 53
9.3.2 Principle of measurement . 53
9.3.3 Test equipment . 55
9.3.4 Test specimen . 55
9.3.5 Test conditions . 55
9.3.6 Test procedure . 56
9.3.7 Calculation and report . 56
9.3.8 Correlation with scleroscope hardness . 56
10 Porosity . 58
10.1 General . 58
10.2 Impregnation-and-mass method . 58
10.2.1 Principle of measurement . 58
10.2.2 Test specimen . 58
IEC 60413:2026 © IEC 2026
10.2.3 Test condition . 59
10.2.4 Impregnating liquid. 59
10.2.5 Test equipment . 59
10.2.6 Test procedure . 60
10.2.7 Calculation . 60
10.3 Mercury method. 62
10.3.1 General. 62
10.3.2 Principle . 62
10.3.3 Test specimen . 62
10.3.4 Test condition . 62
10.3.5 Test equipment . 63
10.3.6 Procedure of measurement . 63
10.3.7 Calculation . 63
11 Ash content . 63
11.1 General . 63
11.2 Principle . 63
11.3 Test specimen . 64
11.4 Test condition . 64
11.5 Test equipment. 64
11.6 Procedure of measurement . 64
11.6.1 Preparing and weighing the specimen: . 64
11.6.2 Ashing the specimen . 64
11.6.3 Weighing the residues . 65
11.7 Calculation . 65
12 Test report . 65
Annex A (normative) Properties per category of test and datasheet . 67
Annex B (normative) Other mechanical properties . 69
B.1 General . 69
B.2 Charpy impact strength . 69
B.2.1 General. 69
B.2.2 Principle of measurement . 69
B.2.3 Test equipment . 70
B.2.4 Test specimen . 71
B.2.5 Test conditions . 72
B.2.6 Procedure of measurement . 72
B.2.7 Calculation and report . 72
B.3 Tensile strength – Young's modulus . 72
B.3.1 General. 72
B.3.2 Principle of measurement of tensile strength . 73
B.3.3 Test equipment . 73
B.3.4 Test specimen . 73
B.3.5 Test conditions . 74
B.3.6 Procedure of measurement . 74
B.3.7 Calculation . 74
B.3.8 Complementary characteristics . 74
B.4 Compressive strength . 75
B.4.1 General. 75
B.4.2 Principle of measurement . 75
IEC 60413:2026 © IEC 2026
B.4.3 Test equipment . 75
B.4.4 Test conditions . 76
B.4.5 Test specimen . 76
B.4.6 Procedure of measurement . 76
B.4.7 Calculation and report . 76
Annex C (normative) Thermal properties . 77
C.1 General . 77
C.2 Coefficient of linear expansion . 77
C.2.1 General. 77
C.2.2 Principle of measurement . 77
C.2.3 Test equipment . 78
C.2.4 Protective gas . 78
C.2.5 Test specimen . 79
C.2.6 Test conditions . 79
C.2.7 Procedure of measurement . 79
C.2.8 Calculation and report . 79
C.3 Specific heat capacity . 81
C.3.1 General. 81
C.3.2 Principle of measurement with DSC . 81
C.3.3 Test equipment . 83
C.3.4 Test specimen . 83
C.3.5 Test conditions . 83
C.3.6 Procedure of measurement . 83
C.3.7 Calculation and report . 83
C.4 Thermal conductivity . 83
C.4.1 General. 83
C.4.2 Flash method. 84
C.4.3 TPS method . 88
C.4.4 Calculation and report . 90
Annex D (informative) Relation between apparent density, real density, porosity and
pores . 92
D.1 General . 92
D.2 Pores . 92
D.3 Apparent density . 92
D.4 Real density . 93
D.5 Porosity . 93
Annex E (informative) Methods for material analysis of sliding contact grades . 94
Annex F (informative) Relation between scleroscope hardness and vibration absorbing
capability . 95
F.1 General . 95
F.2 Vibration equation and amplitude ratio . 95
F.3 Experimental verification . 96
Bibliography . 99
Figure 1 – Dimensions of a test specimen . 10
Figure 2 – Configuration of test specimen in relation to the direction of compression . 20
Figure 3 – Configuration of test specimen in relation to the direction of extrusion . 21
IEC 60413:2026 © IEC 2026
Figure 4 – Test equipment for the measurement of apparent density by immersion
method A on big test specimen . 26
Figure 5 – Test equipment for the measurement of apparent density by immersion
method B on small test specimen . 27
Figure 6 – Measurement of apparent density by immersion method A . 29
Figure 7 – Measurement of apparent density by immersion method B . 30
Figure 8 – Position of measuring electrodes onto the test specimen . 32
Figure 9 – Test specimen mounting configuration for resistivity in case of one-
directional compression . 34
Figure 10 – Test specimen mounting configuration for resistivity in case of extrusion . 34
Figure 11 – Principle of the test equipment of Eddy current method . 36
Figure 12 – Positioning of the test specimen . 38
Figure 13 – Test specimen mounting principle . 39
Figure 14 – Mounting configuration for flexural strength test for a test specimen of
type one-directional compressed . 41
Figure 15 – Mounting configuration for flexural strength test for a test specimen of
type extruded . 41
Figure 16 – Steps for the measurement of indentation hardness . 47
Figure 17 – Principle of scleroscope hardness measurement . 49
Figure 18 – Scleroscope hardness instruments . 50
Figure 19 – Principle of Leeb hardness measurement . 54
Figure 20 – Example of correlation curve assessment between scleroscope hardness
and Leeb hardness . 57
Figure B.1 –Principle of Charpy impact test . 70
Figure B.2 – Configuration of impact strength test for anisotropic materials . 71
Figure B.3 – Example of tensile test specimen . 73
Figure C.1 – Determination of coefficient of linear thermal expansion . 80
Figure C.2 – Schematic drawing showing the DSC baselines . 82
Figure C.3 – Determination of half-time from measurement data. 85
Figure C.4 – Principle of test equipment for thermal pulse method . 87
Figure C.5 – Basic layout of the apparatus . 89
Figure F.1 – Relation between the scleroscope hardness and the amplitude
resonance ratio . 97
Table 1 – Dimensions of test specimen of type B . 19
Table 2 – Configuration type according to the forming process of the item . 21
Table 3 – Tolerances on test specimen dimensions for each category . 22
Table 4 – Recommended values of supports span . 42
Table 5 – Values of coefficient c . 43
f
Table 6 – Calculation of indentation hardness for each combination of scales . 44
Table 7 – Specification of hardness designation . 45
Table 8 – Contents of a report . 66
IEC 60413:2026 © IEC 2026
Table A.1 – Properties per category of tests and datasheet . 67
Table B.1 –Dimensions of test specimen for impact strength test . 71
Table E.1 – Qualitative analysis . 94
Table E.2 – Quantitative analysis . 94
Table F.1 – Values of relative height, damping factor and resonance ratio for different
values of scleroscope hardness . 98
IEC 60413:2026 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Test procedures for determining physical properties of brush materials
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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shall not be held responsible for identifying any or all such patent rights.
IEC 60413 has been prepared by IEC technical committee 2: Rotating machinery. It is an
International Standard.
This second edition cancels and replaces the first edition published in 1972. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Title modified.
b) Addition of definitions in Clause 3.
c) Clause 5 on test specimen: Nomenclature and addition of the different types of test
specimen, specification on their dimensions, tolerances and preparation.
d) Improvement of test procedures of the properties already disclosed in the previous edition
(Clause 6 to Clause 11).
IEC 60413:2026 © IEC 2026
e) Separation of apparent density and apparent porosity (respectively Clause 6 and
Clause 10).
f) Resistivity (Clause 7): Addition of the eddy current method.
g) Rebound hardness (Clause 9): Addition of a new model of scleroscope and addition of Leeb
method, as a possible alternative to the traditional scleroscope method.
h) Common elements of the test report in a dedicated Clause 12.
i) Addition of Annex A (normative): introduction of tests categories (serial/type tests), list of
properties to be tested for each test category of test according to their purpose.
j) Addition of Annex B: test procedures for other mechanical properties than flexural strength
and hardness: tensile, compressive and impact strength.
k) Addition of Annex C: test procedures for thermal properties (coefficient of linear expansion,
specific heat capacity and thermal conductivity).
l) Addition of Annex D: supplement to density and porosity.
m) Addition of Annex E: recommendations on methods for elements analysis.
n) Addition of Annex F: supplement of information concerning scleroscope hardness.
The text of this International Standard is based on the following documents:
Draft Report on voting
2/2286/FDIS 2/2298/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC 60413:2026 © IEC 2026
1 Scope
This document concerns graphite-based grades that are used for sliding electrical contacts,
such as carbon brushes or pantograph strips.
By extension, it is possible to apply the test procedures of this document to all electrical sliding
contacts for electrical transmission appliances and to other appliances of graphite-based
materials (heat exchangers, bearings, etc.).
This document specifies uniformized procedures for determining their following properties:
– density and porosity;
– resistivity;
– flexural strength;
– hardness;
– ash content.
In addition, it provides recommendations on test procedures for other properties:
– Mechanical properties: Charpy impact test, compressive strength, tensile strength
(Annex B).
– Thermal properties: coefficient of thermal expansion, specific heat capacity, thermal
conductivity (Annex C).
The properties determined by these tests are inherent to the graphite-based materials and it is
therefore important to distinguish them from performance characteristics in operation on
electrical equipment (carbon brush in an electrical rotating machine, contact strips on a
pantograph, etc.).
Since these materials are generally brittle, porous materials, it is reasonable that their
properties vary much more than the same properties in metals.
Some test methods are suitable for use in production quality control (routine tests), others only
for more thorough investigations, using precise laboratory techniques (see Annex A).
WARNING — The use of this document can involve hazardous substances, operations and equipment. It does
not purport to address all of the safety or environmental problems associated with its use. It is the
responsibility of the user of this document to establish appropriate safety and health practices and determine
the applicability of regulatory limitations prior to use.
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.
IEC 60276, Carbon brushes, brush holders, commutators and slip-rings - Definitions and
nomenclature
ISO 148-1, Metallic materials - Charpy pendulum impact test - Part 1: Test method
ISO 179-1:2023, Plastics - Determination of Charpy impact properties - Part 1:
Non-instrumented impact test
ISO 6508-2, Metallic materials - Rockwell hardness test - Part 2: Verification and calibration of
testing machines and indenters
IEC 60413:2026 © IEC 2026
ISO 22007-2:2022, Plastics - Determination of thermal conductivity and thermal diffusivity -
Part 2: Transient plane heat source (hot disc) method
3 Terms, definitions and symbols
For the purposes of this document, the terms and definitions given in IEC 60276 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org/
– ISO Online browsing platform: available at https://www.iso.org/obp
3.1
sample
one or more items taken from a lot and intended to provide information on the lot and possibly
to serve as a basis for a decision on the lot or the process which had produced it
Note 1 to entry: One lot is constituted of one or several batches of production, see ISO 2859-1.
[SOURCE: ISO 5022:1979, 2.3, modified – "population" replaced by "lot" and Note 1 to entry
added.]
3.2
test specimen
one or more blocks, drawn from an item of the sample, with di
...