ASTM B684/B684M-22

Standard Specification for Platinum-Iridium Electrical Contact Materials

ABSTRACT
This specification covers two platinum-iridium alloys in the form of rod, wire, strip, and sheet material for electrical contacts. Raw materials shall be of such quality and purity that the finished product (produced by cold working, annealing, turning, grinding, or pickling as required) will have the properties and characteristics prescribed in this specification. The alloys shall meet the requirements of chemical composition specified for platinum, iridium, total impurities, total platinum group (palladium, rhodium, osmium, ruthenium, and gold), total other impurities (including lead, antimony, bismuth, tin, arsenic, cadmium, zinc, and iron) and other elements. Ultimate tensile strength, elongation, microhardness (Knoop or Vickers), hardness (Rockwell or Rockwell Superficial), or a combination of these mechanical properties may be specified as criterion for temper designation. Annealed and work hardened wire and strip shall conform to the mechanical requirements prescribed for ultimate tensile strength, elongation, and microhardness. Knoop hardness test, tension test, and chemical analysis using spectrochemical or wet analysis method shall be performed.
SCOPE
1.1 This specification covers an 80 % platinum—20 % iridium alloy, an 85 % platinum—15 % iridium alloy, and a 90 % platinum—10 % iridium alloy, in the form of rod, wire, strip, and sheet material for electrical contacts.  
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to become familiar with all hazards including those identified in the appropriate Safety Data Sheet (SDS) for this product/material as provided by the manufacturer, to establish appropriate safety, health, and environmental practices, and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Mar-2022
• ICS: 77.120.99 - Other non-ferrous metals and their alloys
• Technical Committee: B02 - Nonferrous Metals and Alloys
• Drafting Committee: B02.05 - Precious Metals and Electrical Contact Materials and Test Methods

Relations

• Refers: ASTM B277-18(2024) - Standard Test Method for Hardness of Electrical Contact Materials
• Effective Date: 01-Apr-2024
• Refers: ASTM E8/E8M-24 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Jan-2024
• Refers: ASTM B542-13(2019) - Standard Terminology Relating to Electrical Contacts and Their Use
• Effective Date: 01-Nov-2019
• Refers: ASTM E8/E8M-16 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 15-Jul-2016
• Refers: ASTM E8/E8M-15 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Feb-2015
• Refers: ASTM E8/E8M-13 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Jun-2013
• Refers: ASTM B542-13 - Standard Terminology Relating to Electrical Contacts and Their Use
• Effective Date: 01-Feb-2013
• Refers: ASTM B277-95(2012) - Standard Test Method for Hardness of Electrical Contact Materials
• Effective Date: 01-May-2012
• Refers: ASTM B476-01(2012) - Standard Specification for General Requirements for Wrought Precious Metal Electrical Contact Materials
• Effective Date: 01-May-2012
• Refers: ASTM E8/E8M-11 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Dec-2011
• Refers: ASTM E384-10 - Standard Test Method for Microindentation Hardness of Materials
• Effective Date: 01-Feb-2010
• Refers: ASTM E384-10e1 - Standard Test Method for Knoop and Vickers Hardness of Materials
• Effective Date: 01-Feb-2010
• Refers: ASTM E384-09 - Standard Test Method for Microindentation Hardness of Materials
• Effective Date: 01-May-2009
• Refers: ASTM E384-08ae1 - Standard Test Method for Microindentation Hardness of Materials
• Effective Date: 15-Mar-2008
• Refers: ASTM E384-08a - Standard Test Method for Microindentation Hardness of Materials
• Effective Date: 15-Mar-2008

Overview

ASTM B684/B684M-22 is the international standard specification governing platinum-iridium electrical contact materials. Developed by ASTM International, this standard outlines the requirements for three specific platinum-iridium alloy compositions-80% platinum/20% iridium, 85% platinum/15% iridium, and 90% platinum/10% iridium-in rod, wire, strip, and sheet forms. These materials are widely recognized for their superior corrosion resistance, electrical conductivity, and mechanical integrity, making them highly suitable for electrical contacts in demanding environments.

The specification details necessary chemical compositions, permissible impurities, mechanical properties, and standardized test methods to ensure that platinum-iridium contact materials deliver consistent performance and quality. Its robust framework helps users and manufacturers achieve reliable results in critical electrical and electronic applications.

Key Topics

• Alloy Composition: The standard covers three distinct platinum-iridium alloy grades, each with tightly controlled ranges for platinum, iridium, and permitted impurities.
• Product Forms: Applicable to rod, wire, strip, and sheet materials used for electrical contacts.
• Mechanical Properties: Requirements for ultimate tensile strength, elongation, and microhardness (Knoop or Vickers), ensuring materials possess suitable strength and ductility for electrical use.
• Quality and Purity: Specifies maximum allowable levels for total impurities and individual impurity elements; the raw materials must be of such purity that finished products meet all prescribed criteria.
• Testing and Inspection: Mandates both chemical and mechanical testing, including tension tests and hardness testing, following referenced ASTM test methods. Material inspection also encompasses dimensional checks and visual examination.
• Ordering Guidance: Outlines the minimum information needed for material procurement, such as alloy grade, temper, product form, dimensions, and required certifications.

Applications

Platinum-iridium alloys standardized under ASTM B684/B684M-22 are essential in the manufacturing and maintenance of electrical contact materials where performance, endurance, and reliability are paramount. Typical applications include:

• Electrical contacts and relays: Leveraging platinum-iridium's excellent resistance to corrosion, wear, and electrical arcing in relays, breakers, and switches.
• Precision instrumentation: Used in laboratory equipment and devices requiring stable and consistent electrical contact performance over time.
• Medical devices: Although not the primary focus of this standard, the biocompatibility of these alloys enables their occasional use in specialized medical components.
• Aerospace and defense electronics: Where mission-critical reliability is necessary in harsh operating conditions, the standardized properties of these alloys ensure safety and consistent performance.
• Scientific and industrial equipment: Instruments such as mass spectrometers or thermocouples benefit from the fine mechanical and electrical characteristics of platinum-iridium contacts.

Related Standards

ASTM B684/B684M-22 references and is complemented by several other ASTM standards relevant to precious metal electrical contact materials and testing methods:

• ASTM B476 - General requirements for wrought precious metal electrical contact materials
• ASTM B277 - Test method for hardness of electrical contact materials
• ASTM B542 - Terminology relating to electrical contacts and their use
• ASTM E8/E8M - Test methods for tension testing of metallic materials
• ASTM E384 - Test method for microindentation hardness of materials

These related standards ensure that all aspects of platinum-iridium electrical contact materials, from terminology and mechanical testing to general requirements, are comprehensively addressed and internationally aligned.

Keywords: platinum-iridium alloys, electrical contact materials, ASTM B684, contact material specification, precious metal contacts, iridium alloy, platinum alloy, mechanical properties, testing methods, industrial standards.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:B684/B684M −22
Standard Specification for
Platinum-Iridium Electrical Contact Materials
This standard is issued under the fixed designation B684/B684M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* B542 Terminology Relating to Electrical Contacts and Their
Use
1.1 This specification covers an 80 % platinum—20 %
E8/E8M Test Methods for Tension Testing of Metallic Ma-
iridium alloy, an 85 % platinum—15 % iridium alloy, and a
terials
90 % platinum—10 % iridium alloy, in the form of rod, wire,
E384 Test Method for Microindentation Hardness of Mate-
strip, and sheet material for electrical contacts.
rials
1.2 The values stated in either SI units or inch-pound units
are to be regarded separately as standard. The values stated in
3. Terminology
each system are not necessarily exact equivalents; therefore, to
3.1 For definitions of terms related to electrical contact
ensure conformance with the standard, each system shall be
materials, refer to Terminology B542.
used independently of the other, and values from the two
systems shall not be combined.
4. General Requirements
1.3 This standard does not purport to address all of the
4.1 The requirements of Specification B476 shall apply to
safety concerns, if any, associated with its use. It is the
all materials produced to this specification.
responsibility of the user of this standard to become familiar
with all hazards including those identified in the appropriate
4.2 In addition, when a section with a title identical to that
Safety Data Sheet (SDS) for this product/material as provided
referenced in 4.1 appears in this specification, it contains
by the manufacturer, to establish appropriate safety, health,
additional requirements which supplement those appearing in
and environmental practices, and determine the applicability
Specification B476.
of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
5. Ordering Information
dance with internationally recognized principles on standard-
5.1 Include the following information when placing orders
ization established in the Decision on Principles for the
for product under this specification, as applicable:
Development of International Standards, Guides and Recom-
5.1.1 ASTM designation and year of issue,
mendations issued by the World Trade Organization Technical
5.1.2 Grade of material (see Table 1),
Barriers to Trade (TBT) Committee.
5.1.3 Temper (annealed or work hardened, see Table 2 and
2. Referenced Documents Table 3),
5.1.4 Form (rod, wire, sheet, or strip),
2.1 ASTM Standards:
5.1.5 Dimensions and tolerances,
B277 Test Method for Hardness of Electrical Contact Mate-
5.1.6 Quantity, total weight or total length or number of
rials
pieces of each size,
B476 Specification for General Requirements for Wrought
5.1.7 Heat identification or traceability details, if required,
Precious Metal Electrical Contact Materials
5.1.8 Certification or test report, or both, if required.
This specification is under the jurisdiction of ASTM Committee B02 on
6. Materials and Manufacture
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
B02.05 on Precious Metals and Electrical Contact Materials.
6.1 Raw materials shall be of such quality and purity that
Current edition approved April 1, 2022. Published April 2022. Originally
the finished product will have the properties and characteristics
approved in 1981. Last previous edition approved in 2016 as B684/B684M – 16.
prescribed in this specification.
DOI: 10.1520/B0684_B0684M-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6.2 The material shall be finished by such operations (cold
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
working, annealing, turning, grinding, or pickling) as are
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. required to produce the prescribed properties.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B684/B684M−22
TABLE 1 Chemical Requirements
80Pt/20Ir 85Pt/15Ir 90Pt/10Ir
Element
Weight % Weight % Weight %
Pt balance balance balance
Ir 19.50 – 20.50 14.50 – 15.50 9.50 – 10.50
Total Impurities 0.2 max 0.2 max 0.2 max
Total Platinum Group (Pd, Rh, Os, Ru), Au 0.1 max 0.1 max 0.1 max
Total Other Impurities (including the 0.1 max 0.1 max 0.1 max
elements below)
Pb, Sb, Bi, Sn, As, Cd, Zn, Hg, Fe 0.01 max each 0.01 max each 0.01 max each
Ni 0.007 max 0.007 max 0.007 max
Other elements 0.02 max each 0.02 max each 0.02 max each
TABLE 2 Mechanical Properties of Wire and Rod
80Pt/20Ir 85Pt/15Ir 90Pt/10Ir
Property
Annealed Work Hardened Annealed Work Hardened Annealed Work Hardened
Ultimate Tensile 85 – 120 130 min 75 – 85 90 min 40 – 60 70 min
Strength, ksi [MPa] [590 – 830] [900 min] [520 – 590] [620 min] [275 – 415] [480 min]
Elongation, % in 10 min 1 min 10 min 1 min 10 min 1 min
2 in. gauge length [51 mm]
Microhardness, 190 – 260 290 min 130 – 190 200 min 120 – 180 190 min
HK
TABLE 3 Mechanical Properties of Strip and Sheet
80Pt/20Ir 85Pt/15Ir 90Pt/10Ir
Property
Annealed Work Hardened Annealed Work Hardened An
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B684/B684M − 16 B684/B684M − 22
Standard Specification for
Platinum-Iridium Electrical Contact Materials
This standard is issued under the fixed designation B684/B684M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This specification covers an 80 % platinum—20 % iridium alloy, an 85 % platinum—15 % iridium alloy, and a 90 %
platinum—10 % iridium alloy, in the form of rod, wire, strip, and sheet material for electrical contacts.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other, and values from the two systems shall not be combined.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to become familiar with all hazards including those identified in the appropriate Safety Data Sheet
(SDS) for this product/material as provided by the manufacturer, to establish appropriate safety safety, health, and healthenvi-
ronmental practices, and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
B277 Test Method for Hardness of Electrical Contact Materials
B476 Specification for General Requirements for Wrought Precious Metal Electrical Contact Materials
B542 Terminology Relating to Electrical Contacts and Their Use
E8/E8M Test Methods for Tension Testing of Metallic Materials
E384 Test Method for Microindentation Hardness of Materials
3. Terminology
3.1 For definitions of terms related to electrical contact materials, refer to Terminology B542.
4. General Requirements
4.1 The requirements of Specification B476 shall apply to all materials produced to this specification.
This specification is under the jurisdiction of ASTM Committee B02 on Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee B02.05 on
Precious Metals and Electrical Contact Materials.
Current edition approved June 1, 2016April 1, 2022. Published June 2016April 2022. Originally approved in 1981. Last previous edition approved in 20122016 as
B684 – 97 (2012).B684/B684M – 16. DOI: 10.1520/B0684_B0684M-16.10.1520/B0684_B0684M-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B684/B684M − 22
4.2 In addition, when a section with a title identical to that referenced in 4.1 appears in this specification, it contains additional
requirements which supplement those appearing in Specification B476.
5. Ordering Information
5.1 Include the following information when placing orders for product under this specification, as applicable:
5.1.1 ASTM designation and year of issue,
5.1.2 Grade of material (see Table 1),
5.1.3 Temper (annealed or work hardened, see Table 2 and Table 3),
5.1.4 Form (rod, wire, sheet, or strip),
5.1.5 Dimensions and tolerances,
5.1.6 Quantity, total weight or total length or number of pieces of each size,
5.1.7 Heat identification or traceability details, if required,
5.1.8 Certification and/or Test Report, or test report, or both, if required.
6. Materials and Manufacture
6.1 Raw materials shall be of such quality and purity that the finished product will have the properties and characteristics
prescribed in this specification.
6.2 The material shall be finished by such operations (cold working, annealing, turning, grinding, or pickling) as are required to
produce the prescribed properties.
7. Chemical Composition
7.1 Material produced under the specification shall meet the requirements of chemical composition prescribed in Table 1.
TABLE 1 Chemical Requirements
85 Pt/15 Ir 90 Pt/10 Ir
Element
Weight % Weight %
Pt balance balance
Ir 14.50-15.50 9.50-10.50
Total Impurities 0.2 max. 0.2 max.
Total Platinum Group (Pd, Rh, Os, Ru), Au 0.1 max. 0.1 max.
Total Other Impurities (including the 0.1 max. 0.1 max.
elements below)
Pb, Sb, Bi, Sn, As, Cd, Zn 0.01 max each 0.01 max each
Fe 0.015 max each 0.015 max each
Other elements 0.02 max each 0.02 max each
TABLE 1 Chemical Requirements
80 Pt/20 Ir 85 Pt/15 Ir 90 Pt/10 Ir
Element
Weight % Weight % Weight %
Pt balance balance balance
Ir 19.50 – 20.50 14.50 – 15.50 9.50 – 10.50
Total Impurities 0.2 max 0.2 max 0.2 max
Total Platinum Group (Pd, Rh, Os, Ru), Au 0.1 max 0.1 max 0.1 max
Total Other Impurities (including the 0.1 max 0.1 max 0.1 max
elements below)
Pb, Sb, Bi, Sn, As, Cd, Zn, Hg, Fe 0.01 max each 0.01 max each 0.01 max each
Ni 0.007 max 0.007 max 0.007 max
Other elements 0.02 max each 0.02 max each 0.02 max each
B684/B684M − 22
TABLE 2 Mechanical Properties of Wire and Rod
80 Pt/20 Ir 85 Pt/15 Ir 90 Pt/10 Ir
Property
Annealed Work Hardened Annealed Work Hardened Annealed Work Hardened
Ultimate Tensile 75 - 85 90 - 120 35 - 60 70 min
Ultimate Tensile 85 – 120 130 min 75 – 85 90 min 40 – 60 70 min
Strength, ksi [MPa] [520-590] [620-830] [240-410] [480 min]
Strength, ksi [MPa] [590 – 830] [900 min] [520 – 590] [620 min] [275 – 415] [480 min]
Elongation, % in 30 min 1 - 10 30 min 1 min
Elongation, % in 10 min 1 min 10 min 1 min 10 min 1 min
2 in. gage length [51 mm]
2 in. gauge length [51 mm]
Microhardness, — — — —
Microhardness, 190 – 260 290 min 130 – 190 200 min 12
...