ASTM B607-91(2008)

This document is not anASTM standard and is intended only to provide the user of anASTM 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:B607–91 (Reapproved 2003) Designation: B 607 – 91 (Reapproved 2008)
Standard Specification for
Autocatalytic Nickel Boron Coatings for Engineering Use
This standard is issued under the fixed designation B 607; 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 Department of Defense.
1. Scope
1.1 Nickel boron coatings are produced by autocatalytic (electroless) deposition from aqueous solutions. These solutions
contain either an alkylamineborane or sodium borohydride as a reducing agent, a source of nickel ions, a buffer, complexant, and
control chemicals.
1.2 This standard describesspecificationdescribes the requirements for coatings of autocatalytic nickel boron deposited from
aqueous solutions onto substrates for engineering use. The specification classifies these coatings into two types:
1.2.1 Type 1 coatings have a boron content of 0.1 to less than 3.5 mass percent with the balance nickel.
1.2.2 Type 2 coatings have a boron content of 3.5 to 6 mass percent and a minimum of 90 mass percent nickel.
1.3 The coatings are hard and uniform in thickness, even on irregular shaped parts, and used in a wide range of applications.
1.4 Process solutions formulated with an alkylamineborane usually produce coatings that contain 0.1 to 3.5 % boron. Thin
coatings of this type provide bondability and solderability on electronic components such as lead frames, electrical contacts, and
headers. To maintain solderability, these coatings are generally not heat treated.
1.5 Process solutions formulated with sodium borohydride are strongly alkaline and are frequently used to plate steel and
titanium parts to impart surface hardness and wear resistance properties. Deposits produced from these processes can contain 3 to
5 % boron and thallium or other metals which are used to stabilize the plating solution and modify the coating properties.
1.6 The physical and mechanical properties of these deposits such as density, hardness, stress, and melting point will vary with
the boron content. The variation of boron content also affects the quantity and structure of nickel boride precipitated during heat
treatment. In the as-plated condition the deposit consists of a predominantly amorphous mixture of nickel and boron with a
hardness of about 700 HKN. When the deposit is heated above 300°C the nickel crystallizes, forming nickel clusters of Ni (111)
and boron precipitates as nickel boride, Ni B (211) and (311), increasing the hardness to greater than 1000 HK for Type 2
3 100
coatings.
1.7 The nickel boron coatings are microporous and offer limited corrosion protection. Their columnar structure, however, is
beneficial in reducing wear because it provides a means of trapping lubricants within the surface of the coated part.
1.8 This document describes only autocatalytic nickel boron coatings that have been produced without use of external electric
sources.
1.9 The following hazards caveat pertains only to theTest Methods section of this specification: This standard does not purport
to address the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate
safety and health practices and determine the applicability of regulatory limitations prior to use.
NOTE 1—The following AMS standards are not requirements. They are referenced for information only: AMS 2399 and AMS 2433.
2. Referenced Documents
2.1 ASTM Standards:
B 374 Terminology Relating to Electroplating
B 487 Test Method for Measurement of Metal and Oxide Coating Thickness by Microscopical Examination of a Cross Section
B 567 Test Method for Measurement of Coating Thickness by the Beta Backscatter Method
B 568 Test Method for Measurement of Coating Thickness by X-Ray Spectrometry
B 571 Practice for Qualitative Adhesion Testing of Metallic Coatings
B 578 Test Method for Microhardness of Electroplated Coatings
This specification is under the jurisdiction ofASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.08.01 on
Engineering Coatings.
Current edition approved Sept. 10, 2003. Published Sept. 2003. Originally approved in 1991. Last previous edition approved in 1998 as B607–91(1998).
Current edition approved Aug. 1, 2008. Published October 2008. Originally approved in 1991. Last previous edition approved in 2003 as B 607 – 91 (2003).
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
, Vol 02.05.volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B 607 – 91 (2008)
B 602 Test Method for Attribute Sampling of Metallic and Inorganic Coatings
B 656 Guide for Autocatalytic (Electroless) Nickel-Phosphorous Deposition on Metals for Engineering and Use
B 667 Practice for Construction and Use of a Probe for Measuring Electrical Contact Resistance
B 678 Test Method for Solderability of Metallic-Coated Products
B 697 Guide for Selection of Sampling Plans for Inspection of Electrodeposited Metallic and Inorganic Coatings
B 762 Test Method of Variables Sampling of Metallic and Inorganic Coatings
D 2670 Test Method for Measuring Wear Properties of Fluid Lubricants (Falex Pin and Vee Block Method)
D 2714 Test Method for Calibration and Operation of the Falex Block-on-Ring Friction and Wear Testing Machine
E39 Test Methods for Chemical Analysis of Nickel
F 519 TestMethodforMechanicalHydrogenEmbrittlementEvaluationofPlating/CoatingProcessesandServiceEnvironments
2.2 Aerospace Materials Specifications:
AMS 2399 Electroless Nickel-Boron Plating
AMS 2433 Electroless Nickel-Thallium-Boron Plating
2.3 U.S. Government Standards:
MIL-STD-105 Sampling Procedures and Tables for Inspection by Attributes
MIL-STD-13165 Shot Peening of Metal Parts
3. Terminology
3.1 Definitions—Many terms used in this standard are defined in Terminology B374Definitions: Many terms used in this
specificationare defined in Terminology B 374.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 cold shut—a void on the surface which has been closed by machining and then partially opened through cleaning.
3.2.2 hot halide stress-corrosion cracking—a type of mechanical failure produced by halogenated solvents that have been
absorbed onto titanium and then in the presence of heat cause microcracking, and the loss of mechanical strength.
3.2.3 lap cracks—a surface imperfection caused by cold working of steels producing a void which can be duplicated in the
deposit.
3.2.4 significant surface—those substrate surfaces which the coating must protect and that are essential to the appearance.
4. Classification
4.1 The classification by type of these coatings establishes the amount of boron in the alloy.
4.1.1 Type 1—Coatings shall contain 0.1 to less than 3.5 mass percent boron with the balance nickel.
4.1.2 Type 2—Coatings shall contain 3.5 to 6 mass percent boron and a minimum of 90 mass percent nickel.
4.2 Theclassificationbyclassofthesecoatingsestablishestheposttreatmenttobeperformedonthepart(s).Theposttreatment
stepsaredesignedtoreducethepotentialforhydrogenembrittlement,increasetheadhesionofthecoatingtothesubstrate,improve
the fatigue properties of the part(s), and increase the wear resistance and hardness of the coating:
4.2.1 Class 1—Parts are supplied as plated with no post heat treatment.
4.2.2 Class 2—Parts are heat treated after plating to increase hardness. The coating is heat treated at 365 to 385°C for 90 min
(see 7.2.4).
4.2.3 Class 3—Parts are heat treated after plating at 180 to 200°C for 2 to 23 h to improve coating adhesion on steel and for
hydrogen embrittlement relief of steels (see 7.2.4).
4.2.4 Class 4—Parts are heat treated after plating at 120 to 130°C for a minimum of1hto improve adhesion on heat-treatable
(age-hardened) aluminum alloys and carburized steels (see 7.2.4).
4.2.5 Class 5—Parts are heat treated after plating at 365 to 375°C for a minimum of4hto improve adhesion on titanium and
titanium alloys (see 7.2.4).
4.3 The classification by grade establishes the minimum thickness of the coating:
4.3.1 Grade A—Parts are plated to a minimum coating thickness of 0.5 µm.
4.3.2 Grade B—Parts are plated to a minimum coating thickness of 12 µm.
4.3.3 Grade C—Parts are plated to a minimum coating thickness of 25 µm.
4.3.4 Grade D—Parts are plated to a minimum coating thickness of 75 µm.
5. Ordering Information
5.1 Thepurchasershouldbeawareofseveralprocessingconsiderationsoroptionsavailabletotheprocessorandwhenordering
should supply the information described in 5.1.1 through 5.1.15 in the purchase order and drawings.
Withdrawn. The last approved version of this historical standard is referenced on www.astm.org.
Annual Book of ASTM Standards, Vol 05.01.
Available from Society of Automotive Engineers (SAE), 400 Commonwealth Dr., Warrendale, PA 15096-0001, http://www.sae.org.
Discontinued; see 1994 Annual Book of ASTM Standards , Vol 03.05.
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700 Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
B 607 – 91 (2008)
5.1.1 Title, ASTM designation, and year of issue of this specification.
5.1.2 Composition and metallurgical condition of the basis metal, assemblies of dissimilar materials must be identified.
5.1.3 Classification of the coating: type, class, and grade for this specification (see Section 4).
5.1.4 Minimum thickness required on the significant surface, and any maximum dimensions or tolerance requirements, if any
(see 7.2.2).
5.1.5 Method of adhesion testing from Test Method B 571 to be used in acceptance requirements (see 8.3).
5.1.6 Requirements for certification and test reports (see Section 11).
5.1.7 Requirements for heat treatment of the part(s) for stress relief prior to plating (see 7.2.4).
5.1.8 Optional sampling plan for lot inspection of the part(s) (see 9.1 and 13.1).
5.1.9 Increased sampling frequency, if any, for qualification tests (see 7.3).
5.1.10 Supplemental requirements for shot peening of the part(s) (see 12.1).
5.1.11 Supplemental requirements for wear testing (see 12.2 and 12.3).
5.1.12 Supplemental requirements for heat treatment in vacuum or inert or reducing atmosphere (see 7.2.1 & 12.4).
5.1.13 Supplemental contact resistance requirements (see 12.5).
5.1.14 Supplemental solderability requirements (see 12.6).
5.1.15 Supplemental U.S. Government requirements, if any (see Section 13).
6. Materials and Manufacture
6.1 Pretreatment—Parts can be processed in accordance with Practice B 656.
6.1.1 A suitable method should be used to remove surface oxides and foreign materials which can cause poor adhesion and
increased porosity.
6.1.2 A suitable method should be used to condition and activate the surface so that an adherent coating will be produced.
6.2 Basis Material and Workmanship— Nickel boron coatings will replicate the surface finish of the basis material.
Imperfectionsinthesurfaceofthebasismaterialincludingscratches,porosity,pits,inclusions,rollanddiemarks,lapcrack,burrs,
cold shuts, and surface roughness that could adversely affect the coating should be brought to the attention of the purchaser prior
to processing (see 7.2.1).
6.3 Stress Relief—Surface-hardened parts can require stress relief before plating.The stress relief heat treatment can reduce the
hardness of some alloys and should therefore be reviewed by all parties before processing (see 5.1.7 and 7.2.4). Shorter times and
higher temperature can be used if the resulting loss of surface hardness is acceptable to the purchaser.
6.4 Hydrogen Embrittlement Relief— Hydrogen embrittlement of high strength steels can be initiated by several different
processing operations. Exposure of the parts to hydrogen sources will generally induce the condition. Care must be exercised
whenever high strength steel is processed to ensure minimal exposure and timely relief treatment.
6.5 Stress-Corrosion Cracking—Titanium and titanium alloys are subject to stress-corrosion cracking after processing.
Pretreatment solutions including rinses should not contain methanol, halogenated hydrocarbon, or more than 50 ppm chlorides, all
of which can cause subsequent stress-corrosion cracking when the parts are heated to 260°C or higher.
7. Requirements Requirements
7.1 Process—The nickel boron coatings shall be produced by autocatalytic nickel deposition from aqueous solutions.
7.2 Acceptance Requirements—The acceptance requirements in 7.2.1 through 7.2.4 are required for all lots of part(s). Each lot
of part(s) shall be sampled with the recommended procedure described in Section 9 of this specification.
7.2.1 Appearance—The coating shall have a uniform appearance without visible imperfections such as blisters, pits, pimples,
and cracks.
7.2.1.1 Imperfections that arise from the surface condition of the basis metal and that cannot be removed using conventional
metal finishing techniques and that persist in the coating shall not be cause for rejection.
7.2.1.2 Discoloration caused by heat treatment shall not be cause for rejection unless specified in the ordering information (see
5.1.12 and 12.4).
7.2.2 Thickness—The coating thickness shall be measured and conform to the specified grade.
7.2.3 Adhesion—The coating shall pass the adhesion test of Test Method B 571 as specified in the ordering information (see
5.1.15).
7.2.4 Heat Treatment:
7.2.4.1 All steel part(s) with a tensile strength of 1000 MPa or greater shall be heat treated at 190 6 15°C for stress relief in
accordance with Table 1 before plating and baked within 3 h after plating for hydrogen embrittlement relief.
7.2.4.2 Class 2 coated part(s) shall be heat treated after plating in accordance with Table 2 for precipitation hardening of the
deposit.
7.2.4.3 Heat treatment for Class 3 coated steel part(s) shall be in accordance with Table 1.
7.2.4.4 Heat treatment for Class 4 and 5 coated part(s) other than steel basis material shall be in accordance with Table 3.
7.3 Qualification Requirements—Coating and pro
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