ASTM B867-95(2023)

Standard Specification for Electrodeposited Coatings of Palladium-Nickel for Engineering Use

ABSTRACT
This specification establishes the requirements for electrodeposited palladium-nickel (Pd-Ni) coatings for engineering applications. Composite coatings consisting of palladium-nickel and a thin gold over-plate for applications involving electrical contacts are also covered. The classification system for the coatings covered here shall be specified by the basis metal, the thickness of the underplating, the composition type and thickness class of the palladium-nickel coating, and the grade of the gold overplating. Coatings should be sampled, tested, and conform to specified requirements as to purity, appearance, thickness, composition, adhesion, ductility, and integrity (including gross defects, mechanical damage, porosity, and microcracks). Alloy composition shall be examined either by wet method, X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Auger or electron probe X-ray microanalysis (EPMA), or wavelength dispersive spectroscopy (WDS). Coating adhesion shall be analyzed either by bend, heat, or cutting test.
SCOPE
1.1 Composition—This specification covers requirements for electrodeposited palladium-nickel coatings containing between 70 and 95 mass % of palladium metal. Composite coatings consisting of palladium-nickel and a thin gold overplate for applications involving electrical contacts are also covered.  
1.2 Properties—Palladium is the lightest and least noble of the platinum group metals. Palladium-nickel is a solid solution alloy of palladium and nickel. Electroplated palladium-nickel alloys have a density between 10 and 11.5, which is substantially less than electroplated gold (17.0 to 19.3) and comparable to electroplated pure palladium (10.5 to 11.8). This yields a greater volume or thickness of coating per unit mass and, consequently, some saving of metal weight. The hardness range of electrodeposited palladium-nickel compares favorably with electroplated noble metals and their alloys (1, 2).2  
Note 1: Electroplated deposits generally have a lower density than their wrought metal counterparts.
Approximate Hardness (HK25)  
Gold  
50–250  
Palladium  
75–600  
Platinum  
150–550  
Palladium-Nickel  
300–650  
Rhodium  
750–1100  
Ruthenium  
600–1300  
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.4  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 establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 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-Oct-2023
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.03 - Engineering Coatings

Relations

• Replaces: ASTM B867-95(2018) - Standard Specification for Electrodeposited Coatings of Palladium-Nickel for Engineering Use
• Effective Date: 01-Nov-2023
• Refers: ASTM B845-97(2024) - Standard Guide for Mixed Flowing Gas (MFG) Tests for Electrical Contacts
• Effective Date: 01-Apr-2024
• Refers: ASTM B849-02(2023) - Standard Specification for Pre-Treatments of Iron or Steel for Reducing Risk of Hydrogen Embrittlement
• Effective Date: 01-Nov-2023
• Refers: ASTM B571-23 - Standard Practice for Qualitative Adhesion Testing of Metallic Coatings
• Effective Date: 01-Nov-2023
• Refers: ASTM B765-03(2023) - Standard Guide for Selection of Porosity and Gross Defect Tests for Electrodeposits and Related Metallic Coatings
• Effective Date: 01-Nov-2023
• Refers: ASTM D3951-18(2023) - Standard Practice for Commercial Packaging
• Effective Date: 01-Oct-2023
• Refers: ASTM B849-02(2019) - Standard Specification for Pre-Treatments of Iron or Steel for Reducing Risk of Hydrogen Embrittlement
• Effective Date: 01-Apr-2019
• Refers: ASTM B845-97(2018) - Standard Guide for Mixed Flowing Gas (MFG) Tests for Electrical Contacts
• Effective Date: 01-Nov-2018
• Refers: ASTM B765-03(2018) - Standard Guide for Selection of Porosity and Gross Defect Tests for Electrodeposits and Related Metallic Coatings
• Effective Date: 01-Aug-2018
• Refers: ASTM B571-18 - Standard Practice for Qualitative Adhesion Testing of Metallic Coatings
• Effective Date: 01-Aug-2018
• Refers: ASTM D3951-18 - Standard Practice for Commercial Packaging
• Effective Date: 01-May-2018

Overview

ASTM B867-95(2023): Standard Specification for Electrodeposited Coatings of Palladium-Nickel for Engineering Use is an internationally recognized specification developed by ASTM to ensure quality and performance of electrodeposited palladium-nickel (Pd-Ni) coatings in engineering applications. This standard details the requirements for Pd-Ni coatings containing 70-95% palladium, including composite coatings with a thin gold overplate, particularly for applications involving electrical contacts. The specification addresses coating classification, performance criteria, test methods, and quality assurance to support reliable, durable, and cost-effective metal finishing for a broad range of industries.

Key Topics

• Composition Requirements: Covers electrodeposited Pd-Ni coatings with palladium content from 70% to 95%. Also allows for composite coatings using a thin gold layer for enhanced electrical contact performance.
• Classification System: Coatings are classified based on basis metal, underplating thickness, Pd-Ni composition and thickness, and gold overplate grade.
• Coating Properties: Highlights density and hardness properties, showing that Pd-Ni coatings offer a lighter, harder alternative to gold, with comparable durability to other noble metals.
• Quality and Performance Testing: Specifies methods for verifying purity, thickness, composition, adhesion, ductility, and overall integrity (including freedom from defects and porosity).
• Testing Methods: Includes requirements for laboratory analysis using techniques such as X-ray fluorescence (XRF), scanning electron microscopy (SEM/EDS), Auger, and other spectrometric and mechanical testing methods.
• Safety and Compliance: Reminds users to consider health, safety, and environmental practices in accordance with regulatory standards and international standardization principles.

Applications

ASTM B867-95(2023) is widely used across industries that require dependable metallic coatings to enhance product performance and longevity. Key applications include:

• Electrical Contacts and Connectors: Pd-Ni coatings are favored for their excellent electrical conductivity, wear resistance, and cost efficiency, especially when a gold overplate is used to enhance mating durability, reduce friction, and prevent corrosion.
• Electronics Manufacturing: Used for printed circuit board edge connectors, low-energy switching devices, and microelectronic components where reliable contact resistance is critical.
• General Engineering: Offers superior protection and aesthetic value to components needing high-performance, corrosion-resistant surfaces with strict adherence to mechanical and appearance standards.
• Aerospace and Telecommunications: Ensures robust and stable contacts in demanding environments by leveraging the hardness and lower density of Pd-Ni compared to gold.
• Jewelry and Precision Instrumentation: Valued for its attractive appearance, durability, and hypoallergenic properties.

Related Standards

Implementing ASTM B867-95(2023) often requires cross-referencing with other relevant standards for proper material preparation, testing, and evaluation, including but not limited to:

• ASTM B488 - Specification for Electrodeposited Coatings of Gold for Engineering Uses
• ASTM B487, B568, B748 - Test Methods for Measurement of Coating Thickness
• ASTM B571 - Practice for Qualitative Adhesion Testing of Metallic Coatings
• ASTM B542 - Terminology Relating to Electrical Contacts and Their Use
• ASTM B845, B827 - Guide and Test Methods for Mixed Flowing Gas Tests
• ASTM B849, B850 - Pre- and Post-coating Treatments for Steel to Reduce Hydrogen Embrittlement
• ASTM B765 - Guide for Porosity and Gross Defect Tests for Electrodeposits

Practical Value

Adopting ASTM B867-95(2023) allows manufacturers and engineers to:

• Enhance Reliability: By following stringent performance and testing protocols, finished components exhibit improved wear resistance, adhesion, and electrical performance.
• Reduce Costs: The lower density of Pd-Ni compared to gold provides material savings without compromising coating quality.
• Ensure Compatibility: Clear guidelines for underplating, overplating, and thickness control help avoid common defects and incompatibility issues during assembly and in-service use.
• Support International Trade: Compliance with this ASTM standard, developed under WTO TBT principles, facilitates seamless international procurement and quality assurance.
• Maintain Regulatory Compliance: Integrates best practices for safety, health, and the environment, aligning with current global standards.

Keywords: ASTM B867-95, palladium-nickel coatings, electrodeposited coatings, Pd-Ni standard, gold overplate, electrical contacts, engineering coatings specification, metal finishing standards, coating classification, performance testing, XRF analysis, adhesion testing.

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: B867 − 95 (Reapproved 2023)
Standard Specification for
Electrodeposited Coatings of Palladium-Nickel for
Engineering Use
This standard is issued under the fixed designation B867; 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.
1. Scope 1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 Composition—This specification covers requirements
ization established in the Decision on Principles for the
for electrodeposited palladium-nickel coatings containing be-
Development of International Standards, Guides and Recom-
tween 70 mass % and 95 mass % of palladium metal. Com-
mendations issued by the World Trade Organization Technical
posite coatings consisting of palladium-nickel and a thin gold
Barriers to Trade (TBT) Committee.
overplate for applications involving electrical contacts are also
covered.
2. Referenced Documents
1.2 Properties—Palladium is the lightest and least noble of
2.1 ASTM Standards:
the platinum group metals. Palladium-nickel is a solid solution
B183 Practice for Preparation of Low-Carbon Steel for
alloy of palladium and nickel. Electroplated palladium-nickel
Electroplating
alloys have a density between 10 and 11.5, which is substan-
B242 Guide for Preparation of High-Carbon Steel for Elec-
tially less than electroplated gold (17.0 to 19.3) and compa-
troplating
rable to electroplated pure palladium (10.5 to 11.8). This yields
B254 Practice for Preparation of and Electroplating on
a greater volume or thickness of coating per unit mass and,
Stainless Steel
consequently, some saving of metal weight. The hardness
B281 Practice for Preparation of Copper and Copper-Base
range of electrodeposited palladium-nickel compares favorably
Alloys for Electroplating and Conversion Coatings
with electroplated noble metals and their alloys (1, 2).
B322 Guide for Cleaning Metals Prior to Electroplating
NOTE 1—Electroplated deposits generally have a lower density than
B343 Practice for Preparation of Nickel for Electroplating
their wrought metal counterparts.
with Nickel
Approximate Hardness (HK )
B374 Terminology Relating to Electroplating
Gold 50–250
B481 Practice for Preparation of Titanium and Titanium
Palladium 75–600
Platinum 150–550 Alloys for Electroplating
Palladium-Nickel 300–650
B482 Practice for Preparation of Tungsten and Tungsten
Rhodium 750–1100
Alloys for Electroplating
Ruthenium 600–1300
B487 Test Method for Measurement of Metal and Oxide
1.3 The values stated in SI units are to be regarded as the
Coating Thickness by Microscopical Examination of
standard. The values given in parentheses are for information
Cross Section
only.
B488 Specification for Electrodeposited Coatings of Gold
1.4 This standard does not purport to address all of the
for Engineering Uses
safety concerns, if any, associated with its use. It is the
B489 Practice for Bend Test for Ductility of Electrodepos-
responsibility of the user of this standard to establish appro-
ited and Autocatalytically Deposited Metal Coatings on
priate safety, health, and environmental practices and deter-
Metals
mine the applicability of regulatory limitations prior to use.
B507 Practice for Design of Articles to Be Electroplated on
Racks
B542 Terminology Relating to Electrical Contacts and Their
Use
This specification is under the jurisdiction of ASTM Committee B08 on
Metallic and Inorganic Coatings and is under the direct responsibility of Subcom-
mittee B08.03 on Engineering Coatings.
Current edition approved Nov. 1, 2023. Published November 2023. Originally
approved in 1995. Last previous edition approved in 2018 as B867 – 95 (2018). For referenced ASTM standards, visit the ASTM website, www.astm.org, or
DOI: 10.1520/B0867-95R23. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
The boldface numbers in parentheses refer to the list of references at the end of Standards volume information, refer to the standard’s Document Summary page on
this specification. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B867 − 95 (2023)
B558 Practice for Preparation of Nickel Alloys for Electro- 4. Classification
plating
4.1 Orders for articles to be plated in accordance with this
B568 Test Method for Measurement of Coating Thickness
specification shall specify the coating system, indicating the
by X-Ray Spectrometry
basis metal, the thicknesses of the underplatings, the type and
B571 Practice for Qualitative Adhesion Testing of Metallic
thickness class of the palladium-nickel coating, and the grade
Coatings
of the gold overplating according to Table 1, Table 2, and Table
B602 Guide for Attribute Sampling of Metallic and Inor-
3. See Section 7.
ganic Coatings
B697 Guide for Selection of Sampling Plans for Inspection
5. Ordering Information
of Electrodeposited Metallic and Inorganic Coatings
5.1 In order to make the application of this specification
B741 Test Method for Porosity In Gold Coatings On Metal
complete, the purchaser shall supply the following information
Substrates By Paper Electrography (Withdrawn 2005)
to the seller in the purchase order or other governing document:
B748 Test Method for Measurement of Thickness of Metal-
5.1.1 The name, designation, and date of issue of this
lic Coatings by Measurement of Cross Section with a
specification;
Scanning Electron Microscope
5.1.2 The coating system including basis metal, composi-
B762 Guide of Variables Sampling of Metallic and Inorganic
tion type, thickness class and gold overplate grade (see 4.1 and
Coatings
Table 1, Table 2, and Table 3);
B765 Guide for Selection of Porosity and Gross Defect Tests
5.1.3 Presence, composition, and thickness of underplating
for Electrodeposits and Related Metallic Coatings
(see 3.2.1). For nickel underplating see 6.5.1;
B798 Test Method for Porosity in Gold or Palladium Coat-
5.1.4 Significant surfaces shall be defined (see 3.2.3);
ings on Metal Substrates by Gel-Bulk Electrography
5.1.5 Requirements, if any, for porosity testing (see 9.6);
B799 Test Method for Porosity in Gold and Palladium
5.1.6 (Steel parts only) Stress relief if required (see Speci-
Coatings by Sulfurous Acid/Sulfur-Dioxide Vapor
fication B849);
B809 Test Method for Porosity in Metallic Coatings by
5.1.7 (Steel parts only) Hydrogen embrittlement relief (see
Humid Sulfur Vapor (“Flowers-of-Sulfur”)
B850 );
B827 Practice for Conducting Mixed Flowing Gas (MFG)
5.1.8 Sampling plan employed (see Section 8); and,
Environmental Tests
5.1.9 Requirement, if any, for surface coating cleanliness
B845 Guide for Mixed Flowing Gas (MFG) Tests for Elec-
(absence of residual salts). See Appendix X6.
trical Contacts
B849 Specification for Pre-Treatments of Iron or Steel for
6. Manufacture
Reducing Risk of Hydrogen Embrittlement
6.1 Any process that provides an electrodeposit capable of
B850 Guide for Post-Coating Treatments of Steel for Reduc-
meeting the specified requirements will be acceptable.
ing the Risk of Hydrogen Embrittlement
D1125 Test Methods for Electrical Conductivity and Resis- 6.2 Substrate:
tivity of Water
6.2.1 The surface condition of the basis metal should be
D3951 Practice for Commercial Packaging specified and should meet this specification prior to the plating
of the parts.
3. Terminology
6.2.2 Defects in the surface of the basis metal, such as
3.1 Definitions: Many terms used in this specification are scratches, porosity, pits, inclusions, roll and die marks, laps,
defined in Terminology B374 or B542. cracks, burrs, cold shuts, and roughness may adversely affect
the appearance and performance of the deposit, despite the
3.2 Definitions of Terms Specific to This Standard:
observance of the best plating practice. Any such defects on
3.2.1 overplating, n—a coating applied onto the topmost
significant surfaces should be brought to the attention of the
palladium-nickel coating. The thickness of an overplating or
supplier and the purchaser.
“flash” is usually less than 0.25 μm.
6.2.3 Clean the basis metal as necessary to ensure a satis-
3.2.2 significant surfaces, n—those surfaces normally vis-
factory surface for subsequent electroplating in accordance
ible (directly or by reflection) or which are essential to the
with Practices B183, B242, B254, B281, B322, B343, B481,
serviceability or function of the article; or which can be the
B482, and B558.
source of corrosion products or tarnish films that interfere with
6.2.4 Proper preparatory procedures and thorough cleaning
the function or desirable appearance of the article. The signifi-
of the basis metal are essential for satisfactory adhesion and
cant surfaces shall be indicated on the drawings of the parts, or
performance of these coatings. The surface must be chemically
by the provision of suitably marked samples.
3.2.3 underplating, n—a metallic coating layer or layers
TABLE 1 Composition Type
between the basis metal or substrate and the palladium-nickel
coating. The thickness of an underplating is usually greater Type Nominal Composition (Mass %) Range (Mass% Pd)
than 1 μm, in contrast to a strike which is thinner. I 75 % Pd/25 % Ni 70–80 % Pd
II 80 % Pd/20 % Ni 75–85 % Pd
III 85 % Pd/15 % Ni 80–90 % Pd
The last approved version of this historical standard is referenced on IV 90 % Pd/10 % Ni 85–95 % Pd
www.astm.org.
B867 − 95 (2023)
A
TABLE 2 Thickness Class
6.5.3 Plating—Good practice calls for the work to be
Thickness Class Minimum Thickness of Pd-Ni (μm)
electrically connected when entering the palladium-nickel
0.4 0.4
solution.
0.5 0.5
0.7 0.7
NOTE 5—Some palladium-nickel electroplating solutions attack copper.
1.0 1.0
This can result in codeposition of copper impurity. The situation is further
1.3 1.3
aggravated when low current densities are utilized. Copper can be
1.5 1.5 2
removed from solutions by low current density electrolysis (0.1 mA ⁄cm
2.0 2.0
to 0.3 mA ⁄cm ).
2.5 2.5
3.0 3.0
6.5.4 Gold Overplating—Apply a thin gold overplating after
A
See Appendix X3 on Electrical Contact Performance Versus Thickness Class.
the palladium-nickel in any application in which palladium-
nickel plated electrical connectors are mated together in a
contact pair. This process is necessary to preserve the perfor-
A
TABLE 3 Gold Overplate
mance of the contact surface. See Appendix X1 for other
MIL-G- Thickness
Grade Type Hardness (Code)
reasons for using a gold overplate.
45204 Range
0 No Overplate . . .
NOTE 6—When using Type 1 gold, the thickness of the gold overplate
1 1 (99.9 % Au min) III 90 HK max (A) 0.05–0.12 μm
shall not exceed 0.12 μm (5 μin.) due to increased risk of degrading
2 2 (99.7 % Au min) I 130–200 HK (C) 0.05–0.25 μm
durability and increasing the coefficient of friction.
A
See Specification B488 and Appendix X1 and Appendix X2.
6.5.5 Residual Salts—For rack and barrel plating
applications, residual plating salts can be removed from the
articles by a clean, hot (50 °C to 100 °C) water rinse. A
minimum rinse time of 2.5 min (racks) or 5 min (barrel) is
clean and continuously conductive, that is, without inclusions
suggested. Best practice calls for a minimum of three dragout
or other contaminants. The coatings must be smooth and as free
rinses and one running rinse with dwell times of 40 s in each
of scratches, gouges, nicks, and similar imperfections as
station when rack plating and 80 s when barrel plating. Modern
possible.
high-velocity impingement type rinses can reduce this time to
a few seconds. This is particularly useful in automatic reel-to-
NOTE 2—A metal finisher can often remove defects through special
treatments such as grinding, polishing, abrasive blasting, chemical reel applications where dwell times are significantly reduced.
treatments, and electropolishing. However, these may not be normal in the
See Appendix X6.
treatment steps preceding the plating, and a special agreement is indicated.
6.3 If required (see 5.1.6), steel parts with a hardness greater
7. Coating Requirements
than 1000 MPa (31 HRC) shall be given a suitable stress relief
7.1 Nature of Coating—The palladium-nickel deposit shall
heat treatment prior to plating in accordance with Specification
have a minimum purity of 70 mass % palladium.
B849. Such stress relief shall not reduce the hardness to a value
7.2 Composition—The composition of the palladium-nickel
below the specified minimum. Avoid acid pickling of high
electrodeposit shall be within 65 mass % of the specified type.
strength steels.
6.3.1 Apply the coating after all basis metal preparatory heat
7.3 Appearance—Palladium-nickel coatings shall be
treatments and mechanical operations on significant surfaces
coherent, continuous, and have a uniform appearance to the
have been completed.
extent that the nature of the basis metal and good commercial
practices permit.
6.4 Racking:
6.4.1 Position parts to allow free circulation of solution over
7.4 Thickness—Everywhere on the significant surface (see
all surfaces. The location of rack or wire marks in the coating
5.1), the thickness of the palladium-nickel coating shall be
should be agreed upon between the producer and supplier.
equal to or exceed the specified thickness. The maximum
thickness, however, shall not exceed the drawing tolerance.
6.5 Plating Process:
6.5.1 Nickel Underplating—Apply a nickel underplating
NOTE 7—The coating thickness requirement of this specification is a
before the palladium-nickel when the product is made from
minimum requirement, that is, the coating thickness is required to equal or
copper or copper alloy. Nickel underplatings are also applied
exceed the specified thickness everywhere on the significant surfaces
while conforming to all maximum thickness tolerances given in the
for other reasons. See Appendix X5.
engineering drawing. Variation in the coating thickness from point to point
NOTE 3—In certain instances where high frequency analog signals are
on a coated article is an inherent characteristic of electroplating processes.
employed, such as wave guides, the magnetic properties of nickel may
The coating thickness at any single point on the significant surface,
attenuate the signal. Palladium-nickel itself is non-ferromagnetic when the
therefore, will sometimes have to exceed the specified value in order to
nickel content is less than 14 mass %.
ensure that the thickness equals or exceeds the specified value at all points.
NOTE 4—In applications where forming or flaring operations are to be
Hence, most average coating thicknesses will be greater than the specified
applied to the plated component, a ductile nickel electrodeposit should be
value. How much greater is largely determined by the shape of the article
specified.
(see Practice B507) and the characteristics of the plating process. In
addition, the average coating thickness on products will vary from article
6.5.2 Strikes—Good practice suggests the use of a palla-
to article within a production lot. If all of the articles in a production lot
dium strike to follow any underplate or substrate (other than
are to meet the thickness requirement, the average coating thickness for
silver or platinum) immediately prior to applying the
the production lot as a whole will be greater than the average necessary to
palladium-nickel. assure that a single article meets the requirement. See 8.1.
B867 − 95 (2023)
7.5 Adhesion—The palladium-nickel coatings shall be ad- needs. The buyer and the seller may agree on the plan or plans
herent to the substrate or underplate when tested by one of the to be used. If they do not, Method B762 identifies the plan to
procedures summarized in 9.5. be used.
7.6 Integrity of the Coating: 8.2 An inspection lot shall be defined as a collection of
7.6.1 Gross Defects/Mechanical Damage—The coatings coated articles that are of the same kind, that have been
shall be free of visible mechanical damage and similar gross produced to the same specifications, coated by a single supplier
defects when viewed at magnifications up to 10×. For some at one time, or at approximately the same time, under essen-
applications this requirement may be relaxed to allow for a tially identical conditions, and that are submitted for accep-
small number of such defects (per unit area), especially if they tance or rejection as a group.
are outside of or on the periphery of the significant surfaces.
9. Test Methods
See 7.6.2.
9.1 Appearance—The coating shall be examined at up to
7.6.2 Porosity—Almost all as-plated electrodeposits contain
10× magnification for conformance to the requirements of
some porosity, and the amount of porosity to be expected for
appearance.
any one type of coating will increase with decreasing the
thickness of that particular coating type. The amount of
9.2 Alloy Composition—Alloy composition of the
porosity in the coating that may be tolerable depends on the
palladium-nickel can be determined by a wet method, X-ray
severity of the environment that the article is likely to
Fluorescence (XRF), Scanning Electron Microscopy (SEM)/
encounter during service or storage. If the pores are few in
Energy Dispersive Spectroscopy (EDS), Auger, or by Electron
number, or away from the significant surfaces, their presence
Probe X-ray Microanalysis (EPMA)/Wavelength Dispersive
can often be tolerated. Acceptance or pass-fail criteria, if
Spectroscopy (WDS).
required, shall be part of the product specification for the
9.2.1 The method chosen for determination of alloy com-
particular article or coating requiring the porosity test. See 9.6.
position shall not be the same method used for determination of
deposit thickness if the deposit is over a nickel underplate or as
NOTE 8—Extensive reviews of porosity and porosity testing can be
found in the literature (3, 4). a referee method. The reason for this is that the determination
of alloy composition and the determination of deposit thickness
8. Sampling
by spectrographic analysis are to some extent interdependent.
See 9.2.4.1 and 9.4.1.
8.1 The purchaser and producer are urged to employ statis-
9.2.2 Wet Method—Use any recognized method to deter-
tical process control in the coating process. Properly
mine quantitatively the relative concentrations of palladium
performed, statistical process control will assure coated prod-
and nickel present. Atomic absorption spectrophotometry (or
ucts of satisfactory quality and will reduce the amount of
any other methods with demonstrated uncertainty less than
acceptance inspection. The sampling plan used for the inspec-
10 %) may be used to determine the alloy composition.
tion of the quality of the coated articles shall be as agreed upon
between the purchaser and the supplier.
NOTE 9—Determination of alloy composition by dissolving the coating
from a test specimen must be obtained by electroplating the palladium-
8.1.1 When a collection of coated articles (the inspection lot
nickel directly over a non-nickel containing alloy substrate with no
(see 8.2)) is examined for compliance with the requirements
intermediate layer. Copper alloy substrates are preferred. Alloy composi-
placed on the articles, a relatively small number of the articles
tion is best determined on a special test specimen. One must be careful to
(the sample) is selected at random and is inspected. The
arrange the specimen so as to electroplate at a typical current density,
inspection lot is then classified as complying or not complying
similar to what is used in production. Palladium-nickel may be stripped by
utilizing a 90 volume % (reagent grade) sulfuric acid, 10 volume %
with the requirements based on the results of the inspection of
(reagent grade) nitric acid solution.
the sample. The size of the sample and the criteria of
compliance are determined by the application of statistics. The 9.2.3 XRF—XRF can be used for composition analysis of
procedure is known as sampling inspection. Test Method B602,
palladium-nickel alloy coatings deposited directly onto copper
Guide B697, and Method B762 contain sampling plans that are or a copper alloy that does not contain nickel. This method is
designed for the sampling inspection of coatings.
not suitable for composition analysis of palladium-nickel alloy
8.1.2 Test Method B602 contains four sampling plans, three coatings less than 60 μm in thickness when deposited over
for use with tests that are non-destructive and one when they
nickel or nickel containing substrates.
are destructive. The buyer and seller may agree on the plan or
NOTE 10—If the palladium-nickel coating is less than 60 μm,
plans to be used. If they do not, Test Method B602 identifies
palladium-nickel alloy composition measurements in the presence of an
the plan to be used.
intermediate nickel layer or nickel containing substrate is degraded by the
fact that the nickel X-ray emission of the alloy layer and the intermediate
8.1.3 Guide B697 provides a large number of plans and also
layer (or substrate) cannot be accurately distinguished from one another.
gives guidance in the selection of a plan. When Guide B697 is
specified, the buyer and seller need to agree on the plan to be 9.2.4 EPMA:
used. 9.2.4.1 EPMA based on electron beam excitation of X-rays
8.1.4 Method B762 can be used only for coating require- characteristic of the elements present can be used to measure
ments that have a numerical limit, such as coating thickness. composition of palladium-nickel alloy coatings on top of any
The test must yield a numerical value and certain statistical undercoat or any substrate to an accuracy of 0.1 mass %
requirements must be met. Method B762 contains several plans palladium if the thickness of the coating is ≥1.5 μm. See
and also gives instructions for calculating plans to meet special Appendix X8.
B867 − 95 (2023)
9.2.4.2 EPMA shall be used as the referee method for the of the article until fracture of the basis metal occurs. Examine
determination of alloy composition. the fracture at a magnification of 10×. Cracking without
9.2.5 SEM/EDS—The SEM/EDS technique is capable of separation does not indicate poor adhesion unless the coating
determining composition of palladium-nickel coatings that are can be peeled back with a sharp instrument.
≥1.5 μm thick to an accuracy and precision of 60.2 mass %
9.5.2 Heat Test—No flaking, blistering, or peeling shall be
palladium. A procedure for calibration of a conventional SEM
apparent at a magnification of 10× after the palladium-nickel
equipped with an X-ray EDS for routine analysis of palladium-
electroplated parts are heated to 300 °C to 350 °C (570 °F to
nickel alloy coating composition appears in Appendix X7.
660 °F) for 30 min and allowed to air cool.
9.2.6 Auger Electron Spectroscopy (AES) and X-ray Photo-
9.5.3 Cutting Test—Make a cut with a sharp instrument and
electron Spectroscopy (XPS)—AES and XPS are capable of
then probe with a sharp point and examine at a magnification
analyzing regions that are of the order of 0.002 μm thick. These
of 10×. No separation of the coating from the substrate or
techniques are potential candidates for analysis of electrode-
intermediate layers shall occur.
posited palladium-nickel alloy coatings with a thickness of
9.6 Plating Integrity—Porosity and microcracks shall be
≥0.03 μm.
determined by either Test Methods B741, B798, B799, or B809
NOTE 11—The use of AES and XPS to determine bulk coating
unless otherwise specified. Do not use the nitric acid vapor test
composition requires the sputter removal of 0.01 to 0.02 μm of ma
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