ASTM B607-91(2009)
(Specification)Standard Specification for Autocatalytic Nickel Boron Coatings for Engineering Use
Standard Specification for Autocatalytic Nickel Boron Coatings for Engineering Use
ABSTRACT
This standard contains the requirements for autocatalytic nickel boron alloy coatings deposited from aqueous solutions without the use of external electric sources. The specification classifies the hard, uniform, microporous, and limited corrosion protection coatings as either Type 1 or Type 2 depending on the boron content. Both the physical and mechanical properties of the coatings such as density, hardness, stress, and melting point also vary with the boron content. In general, these coatings are not heat treated to maintain solderability.
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 specificationdescribes 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, Ni3B (211) and (311), increasing the hardness to greater than 1000 HK100 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 values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.10 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: AMS 2399 and AMS 2433.
X2.1.1 This test method will evaluate the resistance of the coating to abrasive wear. The test is performed on a rotating plated panel that is abraded by two rotating rubber wheels. The panel is weighed before...
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Designation:B607 −91(Reapproved 2009)
Standard Specification for
1
Autocatalytic Nickel Boron Coatings for Engineering Use
This standard is issued under the fixed designation B607; 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 boron with a hardness of about 700 HKN. When the deposit is
heated above 300°C the nickel crystallizes, forming nickel
1.1 Nickel boron coatings are produced by autocatalytic
clusters of Ni (111) and boron precipitates as nickel boride,
(electroless) deposition from aqueous solutions. These solu-
Ni B (211) and (311), increasing the hardness to greater than
3
tions contain either an alkylamineborane or sodium borohy-
1000 HK for Type 2 coatings.
100
dride as a reducing agent, a source of nickel ions, a buffer,
complexant, and control chemicals. 1.7 The nickel boron coatings are microporous and offer
limited corrosion protection. Their columnar structure,
1.2 This specification describes the requirements for coat-
however, is beneficial in reducing wear because it provides a
ings of autocatalytic nickel boron deposited from aqueous
means of trapping lubricants within the surface of the coated
solutions onto substrates for engineering use.The specification
part.
classifies these coatings into two types:
1.2.1 Type 1 coatings have a boron content of 0.1 to less 1.8 Thisdocumentdescribesonlyautocatalyticnickelboron
than 3.5 mass percent with the balance nickel. coatings that have been produced without use of external
1.2.2 Type 2 coatings have a boron content of 3.5 to 6 mass electric sources.
percent and a minimum of 90 mass percent nickel.
1.9 The values stated in SI units are to be regarded as
1.3 The coatings are hard and uniform in thickness, even on standard. No other units of measurement are included in this
irregularshapedparts,andusedinawiderangeofapplications. standard.
1.10 The following hazards caveat pertains only to the Test
1.4 Process solutions formulated with an alkylamineborane
Methods section of this specification: This standard does not
usually produce coatings that contain 0.1 to 3.5 % boron. Thin
purport to address the safety problems associated with its use.
coatings of this type provide bondability and solderability on
It is the responsibility of the user of this standard to establish
electronic components such as lead frames, electrical contacts,
appropriate safety and health practices and determine the
and headers. To maintain solderability, these coatings are
applicability of regulatory limitations prior to use.
generally not heat treated.
1.5 Process solutions formulated with sodium borohydride NOTE 1—The followingAMS standards are not requirements. They are
referenced for information only: AMS 2399 and AMS 2433.
are strongly alkaline and are frequently used to plate steel and
titanium parts to impart surface hardness and wear resistance
2. Referenced Documents
properties.Depositsproducedfromtheseprocessescancontain
2
2.1 ASTM Standards:
3 to 5 % boron and thallium or other metals which are used to
B374 Terminology Relating to Electroplating
stabilizetheplatingsolutionandmodifythecoatingproperties.
B487 Test Method for Measurement of Metal and Oxide
1.6 The physical and mechanical properties of these depos-
Coating Thickness by Microscopical Examination of
itssuchasdensity,hardness,stress,andmeltingpointwillvary
Cross Section
with the boron content. The variation of boron content also
B567 Test Method for Measurement of Coating Thickness
affects the quantity and structure of nickel boride precipitated
by the Beta Backscatter Method
during heat treatment. In the as-plated condition the deposit
B568 Test Method for Measurement of Coating Thickness
consists of a predominantly amorphous mixture of nickel and
by X-Ray Spectrometry
B571 Practice for Qualitative Adhesion Testing of Metallic
Coatings
1
This specification is under the jurisdiction of ASTM Committee B08 on
Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee
2
B08.03 on Engineering Coatings. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2009. Published November 2009. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1991. Last previous edition approved in 2008 as B607 – 91 (2008). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/B0607-91R09. the ASTM website.
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