ASTM B607-91(1998)
(Specification)Standard Specification for Autocatalytic Nickel Boron Coatings for Engineering Use
Standard Specification for Autocatalytic Nickel Boron Coatings for Engineering Use
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 describes 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 100 for Type 2 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 the Test 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: AMS2399 and AMS2433.
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Standards Content (Sample)
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Designation: B 607 – 91 (Reapproved 1998)
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 (e) 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 1.7 The nickel boron coatings are microporous and offer
limited corrosion protection. Their columnar structure, how-
1.1 Nickel boron coatings are produced by autocatalytic
ever, is beneficial in reducing wear because it provides a means
(electroless) deposition from aqueous solutions. These solu-
of trapping lubricants within the surface of the coated part.
tions contain either an alkylamineborane or sodium borohy-
1.8 This document describes only autocatalytic nickel boron
dride as a reducing agent, a source of nickel ions, a buffer,
coatings that have been produced without use of external
complexant, and control chemicals.
electric sources.
1.2 This standard describes the requirements for coatings of
1.9 The following hazards caveat pertains only to the Test
autocatalytic nickel boron deposited from aqueous solutions
Methods section of this specification: This standard does not
onto substrates for engineering use. The specification classifies
purport to address the safety problems associated with its use.
these coatings into two types:
It is the responsibility of the user of this standard to establish
1.2.1 Type 1 coatings have a boron content of 0.1 to less
appropriate safety and health practices and determine the
than 3.5 mass percent with the balance nickel.
applicability of regulatory limitations prior to use.
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.
NOTE 1—The following AMS standards are not requirements. They are
1.3 The coatings are hard and uniform in thickness, even on
referenced for information only: AMS 2399 and AMS 2433.
irregular shaped parts, and used in a wide range of applications.
2. Referenced Documents
1.4 Process solutions formulated with an alkylamineborane
2.1 ASTM Standards:
usually produce coatings that contain 0.1 to 3.5 % boron. Thin
coatings of this type provide bondability and solderability on B 374 Terminology Relating to Electroplating
B 487 Test Method for Measurement of Metal and Oxide
electronic components such as lead frames, electrical contacts,
and headers. To maintain solderability, these coatings are Coating Thickness by Microscopical Examination of a
Cross Section
generally not heat treated.
1.5 Process solutions formulated with sodium borohydride B 567 Test Method for Measurement of Coating Thickness
by Beta Backscatter Method
are strongly alkaline and are frequently used to plate steel and
titanium parts to impart surface hardness and wear resistance B 568 Test Method for Measurement of Coating Thickness
by X-Ray Spectrometry
properties. Deposits produced from these processes can contain
B 571 Test Method for Adhesion of Metallic Coatings
3 to 5 % boron and thallium or other metals which are used to
stabilize the plating solution and modify the coating properties. B 578 Test Method for Microhardness of Electroplated
Coatings
1.6 The physical and mechanical properties of these depos-
its such as density, hardness, stress, and melting point will vary B 602 Test Method for Attribute Sampling of Metallic and
Inorganic Coatings
with the boron content. The variation of boron content also
affects the quantity and structure of nickel boride precipitated B 656 Guide for Autocatalytic (Electroless) Nickel-
Phosphorus Deposition on Metals for Engineering Use
during heat treatment. In the as-plated condition the deposit
consists of a predominantly amorphous mixture of nickel and B 667 Practice for Construction and Use of a Probe for
Measuring Electrical Contact Resistance
boron with a hardness of about 700 HKN. When the deposit is
heated above 300°C the nickel crystallizes, forming nickel B 678 Test Method for Solderability of Metallic-Coated
Products
clusters of Ni (111) and boron precipitates as nickel boride,
Ni B (211) and (311), increasing the hardness to greater than B 697 Guide for Selection of Sampling Plans for Inspection
of Electrodeposited Metallic and Inorganic Coatings
1000 HK for Type 2 coatings.
This specification is under the jurisdiction of ASTM Committee B-8 on
Metallic and Inorganic Coatingsand is the direct responsibility of Subcommittee
B08.08.01 on Engineering Coatings. Annual Book of ASTM Standards, Vol 02.05.
Current edition approved Feb. 22, 1991. Published May 1991. Annual Book of ASTM Standards, Vol 03.04.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
B 607
B 762 Method of Variables Sampling of Metallic and Inor- 4.2.2 Class 2—Parts are heat treated after plating to increase
ganic Coatings hardness. The coating is heat treated at 365 to 385°C for 90
D 2670 Test Method for Measuring Wear Properties of min (see 7.2.4).
Fluid Lubricants (Falex Pin and Vee Block Method) 4.2.3 Class 3—Parts are heat treated after plating at 180 to
D 2714 Test Method for Calibration and Operation of the 200°C for 2 to 23 h to improve coating adhesion on steel and
Falex Block-on-Ring Friction and Wear Testing Machine for hydrogen embrittlement relief of steels (see 7.2.4).
E 39 Test Methods for Chemical Analysis of Nickel 4.2.4 Class 4—Parts are heat treated after plating at 120 to
F 519 Test Method for Mechanical Hydrogen Embrittle- 130°C for a minimum of1hto improve adhesion on
ment Testing of Plating Processes and Aircraft Mainte- heat-treatable (age-hardened) aluminum alloys and carburized
nance Chemicals steels (see 7.2.4).
2.2 Aerospace Materials Specifications: 4.2.5 Class 5—Parts are heat treated after plating at 365 to
AMS 2399 Electroless Nickel-Boron Plating 375°C for a minimum of4hto improve adhesion on titanium
AMS 2433 Electroless Nickel-Thallium-Boron Plating and titanium alloys (see 7.2.4).
2.3 U.S. Government Standards: 4.3 The classification by grade establishes the minimum
MIL-STD-105 Sampling Procedures and Tables for Inspec- thickness of the coating:
tion by Attributes 4.3.1 Grade A—Parts are plated to a minimum coating
MIL-STD-13165 Shot Peening of Metal Parts thickness of 0.5 μm.
4.3.2 Grade B—Parts are plated to a minimum coating
3. Terminology
thickness of 12 μm.
4.3.3 Grade C—Parts are plated to a minimum coating
3.1 Definitions—Many terms used in this standard are
thickness of 25 μm.
defined in Terminology B 374.
4.3.4 Grade D—Parts are plated to a minimum coating
3.2 Definitions of Terms Specific to This Standard:
thickness of 75 μm.
3.2.1 cold shut—a void on the surface which has been
closed by machining and then partially opened through clean-
5. Ordering Information
ing.
5.1 The purchaser should be aware of several processing
3.2.2 hot halide stress-corrosion cracking—a type of me-
considerations or options available to the processor and when
chanical failure produced by halogenated solvents that have
ordering should supply the information described in 5.1.1
been absorbed onto titanium and then in the presence of heat
through 5.1.15 in the purchase order and drawings.
cause microcracking, and the loss of mechanical strength.
5.1.1 Title, ASTM designation, and year of issue of this
3.2.3 lap cracks—a surface imperfection caused by cold
specification.
working of steels producing a void which can be duplicated in
5.1.2 Composition and metallurgical condition of the basis
the deposit.
metal, assemblies of dissimilar materials must be identified.
3.2.4 significant surface—those substrate surfaces which
5.1.3 Classification of the coating: type, class, and grade for
the coating must protect and that are essential to the appear-
this specification (see Section 4).
ance.
5.1.4 Minimum thickness required on the significant sur-
4. Classification face, and any maximum dimensions or tolerance requirements,
if any (see 7.2.2).
4.1 The classification by type of these coatings establishes
5.1.5 Method of adhesion testing from Test Method B 571
the amount of boron in the alloy.
to be used in acceptance requirements (see 8.3).
4.1.1 Type 1—Coatings shall contain 0.1 to less than 3.5
5.1.6 Requirements for certification and test reports (see
mass percent boron with the balance nickel.
Section 11).
4.1.2 Type 2—Coatings shall contain 3.5 to 6 mass percent
5.1.7 Requirements for heat treatment of the part(s) for
boron and a minimum of 90 mass percent nickel.
stress relief prior to plating (see 7.2.4).
4.2 The classification by class of these coatings establishes
5.1.8 Optional sampling plan for lot inspection of the part(s)
the post treatment to be performed on the part(s). The post
(see 9.1 and 13.1).
treatment steps are designed to reduce the potential for
5.1.9 Increased sampling frequency, if any, for qualification
hydrogen embrittlement, increase the adhesion of the coating
tests (see 7.3).
to the substrate, improve the fatigue properties of the part(s),
5.1.10 Supplemental requirements for shot peening of the
and increase the wear resistance and hardness of the coating:
part(s) (see 12.1).
4.2.1 Class 1—Parts are supplied as plated with no post heat
5.1.11 Supplemental requirements for wear testing (see 12.2
treatment.
and 12.3).
5.1.12 Supplemental requirements for heat treatment in
vacuum or inert or reducing atmosphere (see 7.2.1 & 12.4).
Annual Book of ASTM Standards, Vol 05.02.
5.1.13 Supplemental contact resistance requirements (see
Discontinued; see 1995 Annual Book of ASTM Standards, Vol 03.05.
Annual Book of ASTM Standards, Vol 15.03.
12.5).
Available from Society of Automotive Engineers, Inc. (SAE), 400 Common-
5.1.14 Supplemental solderability requirements (see 12.6).
wealth Drive, Warrendale, PA 15096.
8 5.1.15 Supplemental U.S. Government requirements, if any
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS. (see Section 13).
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
B 607
6. Materials and Manufacture 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
6.1 Pretreatment—Parts can be processed in accordance
in accordance with Table 1 before plating and baked within 3
with Practice B 656.
h after plating for hydrogen embrittlement relief.
6.1.1 A suitable method should be used to remove surface
7.2.4.2 Class 2 coated part(s) shall be heat treated after
oxides and foreign materials which can cause poor adhesion
plating in accordance with Table 2 for precipitation hardening
and increased porosity.
of the deposit.
6.1.2 A suitable method should be used to condition and
7.2.4.3 Heat treatment for Class 3 coated steel part(s) shall
activate the surface so that an adherent coating will be
be in accordance with Table 1.
produced.
7.2.4.4 Heat treatment for Class 4 and 5 coated part(s) other
6.2 Basis Material and Workmanship— Nickel boron coat-
than steel basis material shall be in accordance with Table 3.
ings will replicate the surface finish of the basis material.
7.3 Qualification Requirements—Coating and process at-
Imperfections in the surface of the basis material including
tributes that require testing on a monthly basis, or more
scratches, porosity, pits, inclusions, roll and die marks, lap
frequently when specified in the ordering information by the
crack, burrs, cold shuts, and surface roughness that could
purchaser. A test specimen or part, processed in a manner that
adversely affect the coating should be brought to the attention
duplicates the characteristics of production parts, shall be
of the purchaser prior to processing (see 7.2.1).
produced and used in these tests.
6.3 Stress Relief—Surface-hardened parts can require stress
7.3.1 Hardness—The hardness of the Type 2, Class 2, Grade
relief before plating. The stress relief heat treatment can reduce
C and D coating shall be not less than 1000 HK as measured
the hardness of some alloys and should therefore be reviewed
by Test Method B 578.
by all parties before processing (see 5.1.7 and 7.2.4). Shorter
7.3.2 Composition—The coating composition produced
times and higher temperature can be used if the resulting loss
from the process shall be analyzed for nickel and boron. The
of surface hardness is acceptable to the purchaser.
alloy produced shall be within the range specified for the
6.4 Hydrogen Embrittlement Relief— Hydrogen embrittle-
coating type.
ment of high strength steels can be initiated by several different
7.3.3 Hydrogen Embrittlement—The process and coating
processing operations. Exposure of the parts to hydrogen
shall be evaluated for freedom from hydrogen embrittlement
sources will generally induce the condition. Care must be
and pass requirements of Test Method F 519.
exercised whenever high strength steel is processed to ensure
minimal exposure and timely relief treatment.
8. Test Methods
6.5 Stress-Corrosion Cracking—Titanium and titanium al-
8.1 Test Specimens:
loys are subject to stress-corrosion cracking after processing.
8.1.1 When separate test specimens are required, the num-
Pretreatment solutions including rinses should not contain
ber to be used, the material from which they are to be made,
methanol, halogenated hydrocarbon, or more than 50 ppm
and their shape and size shall be specified by the purchaser.
chlorides, all of which can cause subsequent stress-corrosion
8.1.2 When separate test specimens are used for acceptance
cracking when the parts are heated to 260°C or higher.
or qualification testing of the coating, the specimens shall be
made of the same material as the part(s), have the same
7. Requirements
metallurgical condition as the part(s), and be processed with
7.1 Process—The nickel boron coatings shall be produced
the part(s).
by autocatalytic nickel deposition from aqueous solutions.
8.2 Thickness—The thickness shall be measured at any
7.2 Acceptance Requirements—The acceptance require-
place on the significant surface designated by the purchaser,
ments in 7.2.1 through 7.2.4 are required f
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