ASTM B765-03(2008)
(Guide)Standard Guide for Selection of Porosity and Gross Defect Tests for Electrodeposits and Related Metallic Coatings
Standard Guide for Selection of Porosity and Gross Defect Tests for Electrodeposits and Related Metallic Coatings
SIGNIFICANCE AND USE
Porosity tests indicate the completeness of protection or coverage offered by the coating. When a given coating is known to be protective when properly deposited, the porosity serves as a measure of the control of the process. The effects of substrate finish and preparation, plating bath, coating process, and handling, may all affect the degree of imperfection that is measured.
Note 1—The substrate exposed by the pores may be the basis metal, an underplate, or both.
The tests in this guide involve corrosion reactions in which the products delineate pores in coatings. Since the chemistry and properties of these products may not resemble those found in service environments, these tests are not recommended for prediction of product performance unless correlation is first established with service experience.
SCOPE
1.1 This guide describes some of the available standard methods for the detection, identification, and measurement of porosity and gross defects in electrodeposited and related metallic coatings and provides some laboratory-type evaluations and acceptances. Some applications of the test methods are tabulated in Table 1 and Table 2.
1.2 This guide does not apply to coatings that are produced by thermal spraying, ion bombardment, sputtering, and other similar techniques where the coatings are applied in the form of discrete particles impacting on the substrate.
1.3 This guide does not apply to beneficial or controlled porosity, such as that present in microdiscontinuous chromium coatings.
1.4 Porosity test results (including those for gross defects) occur as chemical reaction end products. Some occur in situ, others on paper, or in a gel coating. Observations are made that are consistent with the test method, the items being tested, and the requirements of the purchaser. These may be visual inspection (unaided eye) or by 10× magnification (microscope). Other methods may involve enlarged photographs or photomicrographs.
1.5 The test methods are only summarized. The individual standards must be referred to for the instructions on how to perform the tests.
1.6 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.7 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: B765 − 03(Reapproved 2008)
Standard Guide for
Selection of Porosity and Gross Defect Tests for
Electrodeposits and Related Metallic Coatings
This standard is issued under the fixed designation B765; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This guide describes some of the available standard
2.1 ASTM Standards:
methods for the detection, identification, and measurement of
B276Test Method for Apparent Porosity in Cemented Car-
porosity and gross defects in electrodeposited and related
bides
metallic coatings and provides some laboratory-type evalua-
B374Terminology Relating to Electroplating
tions and acceptances. Some applications of the test methods
B537Practice for Rating of Electroplated Panels Subjected
are tabulated in Table 1 and Table 2.
to Atmospheric Exposure
B542Terminology Relating to Electrical Contacts andTheir
1.2 This guide does not apply to coatings that are produced
Use
by thermal spraying, ion bombardment, sputtering, and other
B545Specification for Electrodeposited Coatings of Tin
similartechniqueswherethecoatingsareappliedintheformof
B605Specification for Electrodeposited Coatings of Tin-
discrete particles impacting on the substrate.
Nickel Alloy
1.3 This guide does not apply to beneficial or controlled
B650Specification for Electrodeposited Engineering Chro-
porosity, such as that present in microdiscontinuous chromium
mium Coatings on Ferrous Substrates
coatings.
B689Specification for Electroplated Engineering Nickel
1.4 Porosity test results (including those for gross defects)
Coatings
occur as chemical reaction end products. Some occur in situ,
B733Specification for Autocatalytic (Electroless) Nickel-
othersonpaper,orinagelcoating.Observationsaremadethat
Phosphorus Coatings on Metal
are consistent with the test method, the items being tested, and
B734Specification for Electrodeposited Copper for Engi-
the requirements of the purchaser. These may be visual
neering Uses
inspection (unaided eye) or by 10× magnification (micro-
B735Test Method for Porosity in Gold Coatings on Metal
scope). Other methods may involve enlarged photographs or
Substrates by Nitric Acid Vapor
photomicrographs.
B741Test Method for Porosity In Gold Coatings On Metal
Substrates By Paper Electrography (Withdrawn 2005)
1.5 The test methods are only summarized. The individual
B798Test Method for Porosity in Gold or Palladium Coat-
standards must be referred to for the instructions on how to
ings on Metal Substrates by Gel-Bulk Electrography
perform the tests.
B799Test Method for Porosity in Gold and Palladium
1.6 The values stated in SI units are to be regarded as
Coatings by Sulfurous Acid/Sulfur-Dioxide Vapor
standard. The values given in parentheses are for information
B809Test Method for Porosity in Metallic Coatings by
only.
Humid Sulfur Vapor (“Flowers-of-Sulfur”)
1.7 This standard does not purport to address all of the B866Test Method for Gross Defects and Mechanical Dam-
safety concerns, if any, associated with its use. It is the age in Metallic Coatings by Polysulfide Immersion
responsibility of the user of this standard to establish appro- B877Test Method for Gross Defects and Mechanical Dam-
priate safety and health practices and determine the applica- age in Metallic Coatings by the Phosphomolybdic Acid
bility of regulatory limitations prior to use. (PMA) Method
1 2
This guide is under the jurisdiction ofASTM Committee B08 on Metallic and For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on Test contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Methods. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Aug. 1, 2008. Published September 2008. Originally the ASTM website.
approved in 1986. Last previous edition approved in 2003 as B765–93(2003). The last approved version of this historical standard is referenced on
DOI: 10.1520/B0765-03R08. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B765 − 03 (2008)
TABLE 1 Applications of Standard Porosity Tests to Metallic Coatings (Section 6)
A
Substrate Metal Gold Silver Nickel Tin-Nickel Tin Tin-Lead Copper Palladium Chromium
B
Copper and Copper 6.1 , 6.2, 6.3A 6.4 6.4 6.4 6.4 . 6.2, 6.3A, 6.4, .
6.4, 6.5
Alloys 6.5
B
Nickel 6.1 , 6.2, 6.5 6.3A . . . . . 6.2, 6.3A, 6.5 .
Iron or Steel 6.6 . 6.6 6.3B, 6.6 6.3B, 6.6 6.3B, 6.6 6.6 . 6.6
Silver 6.4 . 6.4 6.4 6.4 6.4 . 6.4 .
A
The substrate may be the basis metal, an underplate, or both (see Note 1).
B
Thickness restrictions may apply.
TABLE 2 Applications of Tests for Gross Defects and Mechanical Damage (Section 7)
A
Substrate Metal Gold Nickel Tin-Nickel Tin Tin-Lead Palladium Silver
Copper and Copper 7.3, 7.5 7.3, 7.4 7.3 7.3 7.3 7.3, 7.5 7.5
Alloys
Nickel 7.5 . . . . 7.5 7.5
Iron or Steel 7.1 7.1 7.1 7.1 7.1 7.1 .
Aluminum . 7.2 . . . . .
A
The substrate may be the basis metal, an underplate, or both (see Note 1).
3. Terminology 5.1.1 Intrinsic or normal porosity is due primarily to small
deviations from ideal plating and surface preparation condi-
3.1 Definitions—Many terms used in this guide are defined
tions. As such, it will be present to some degree in all
in Terminology B374 or B542.
commercial thin platings and will generally follow an inverse
3.2 Definitions of Terms Specific to This Standard:
relationship with thickness. In addition, scanning electron
3.2.1 porosity—for the purpose of this guide, porosity in a
microscope (SEM) studies have shown that the diameter of
coating is defined as any hole, crack, or other defect that
suchporesattheplatingsurfaceisoftheorderofmicrometers,
exposes the underlying metal to the environment. Differences
so that only small areas of underlying metal are exposed to the
betweenthemajortypesofporosityaredescribedinSection5.
environment.
3.2.2 underplate—ametalliccoatinglayerbetweenthebasis 5.1.2 Gross defects, on the other hand, would result in
metal and the topmost metallic coating. The thickness of an
comparatively large areas of exposed basis metal or underplat-
underplatingisusuallygreaterthan1µm,incontrasttoastrike ing. Examples of such defects are mechanical damage to the
or flash, which are usually thinner.
coatingthroughmishandlingorwear.Grossdefectscanalsobe
found in undamaged coatings in the form of networks of
4. Significance and Use
microcracks and as large as-plated pores—with diameters an
order of magnitude (or more) greater than intrinsic porosity.
4.1 Porosity tests indicate the completeness of protection or
Such gross defects indicate such serious deviations from
coverage offered by the coating. When a given coating is
acceptable coating practice as dirty substrates and contami-
known to be protective when properly deposited, the porosity
nated or out-of-balance baths.
servesasameasureofthecontroloftheprocess.Theeffectsof
substrate finish and preparation, plating bath, coating process,
5.2 Intrinsicporosityandmosttypesofgrossdefectsaretoo
and handling, may all affect the degree of imperfection that is
smalltobeseenexceptatmagnificationssohighthatarealistic
measured.
assessmentoftheoverallcoatingsurfaceinthefunctionalareas
of the part cannot be made. Instead, the presence and severity
NOTE1—Thesubstrateexposedbytheporesmaybethebasismetal,an
underplate, or both. of the porosity is normally determined by some type of
pore-corrosion test that will magnify the pore sites by produc-
4.2 The tests in this guide involve corrosion reactions in
ingvisiblereactionproductsinandaroundtheporesorcracks.
which the products delineate pores in coatings. Since the
Testsforgrossdefects(Section7),andespeciallyformechani-
chemistry and properties of these products may not resemble
caldamageandwear,aredesignedtobelesssevere.Suchtests,
those found in service environments, these tests are not
however, may not detect a sizeable portion of the smaller
recommended for prediction of product performance unless
(intrinsic) pores in a coating. On the other hand, standard tests
correlation is first established with service experience.
forintrinsicporosity(Section6)willeasilyrevealthepresence
of gross defects as well.
5. Applications
5.3 Porosity tests are generally destructive in nature and are
5.1 From the viewpoint of both porosity testing and func-
designed to assess the quality of the coating process in
tionalsignificance,itisusefultodivideporosityintotwobroad
4,5
categories, namely intrinsic porosity and gross defects.
Krumbein, S. J., “The ASTM Approach to Porosity Testing,” Proc. 1991
Baker, R. G., Holden, C. A., and Mendizza, A., Proceedings of the American International Technical Conf. of theAmerican Electroplaters and Surface Finishers
Electroplaters Society, Vol 50, 1963, p. 61. Soc., (SUR/FIN ’91), Toronto, 1991, pp. 527–536.
B765 − 03 (2008)
conjunction with the substrate. Therefore, separate test speci- of 0.1N sulfuric acid and 0.12N sodium thiosulfate solutions.
mens are not ordinarily allowed. Each reaction product spot on the surface indicates a pore in
the coating.
5.4 In the tests summarized in this guide, chemicals react
6.4 Humid Sulfur Vapor (“Flowers-of-Sulfur”) (Test
withtheexposedsubstratethroughtheporeorchannelto
...
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:B765–93(Reapproved 1997) Designation:B765–03 (Reapproved 2008)
Standard Guide for
Selection of Porosity and Gross Defect Tests for
Electrodeposits and Related Metallic Coatings
This standard is issued under the fixed designation B 765; 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
1.1 This guide describes some of the available standard methods for the detection, identification, and measurement of porosity
and gross defects in electrodeposited and related metallic coatings and provides some laboratory-type evaluations and acceptances.
Some applications of the test methods are tabulated in Table 1 and Table 2.
1.2 Thisguidedoesnotapplytocoatingsthatareproducedbythermalspraying,ionbombardment,sputtering,andothersimilar
techniques where the coatings are applied in the form of discrete particles impacting on the substrate.
1.3 Thisguidedoesnotapplytobeneficialorcontrolledporosity,suchasthatpresentinmicrodiscontinuouschromiumcoatings.
1.4 Porosity test results (including those for gross defects) occur as chemical reaction end products. Some occur in situ, others
on paper, or in a gel coating. Observations are made that are consistent with the test method, the items being tested, and the
requirementsofthepurchaser.Thesemaybevisualinspection(unaidedeye)orby103magnification(microscope).Othermethods
may involve enlarged photographs or photomicrographs.
1.5 The test methods are only summarized. The individual standards must be referred to for the instructions on how to perform
the tests.
1.6 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.7 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
B246Specification for Tinned Hard-Drawn and Medium-Hard-Drawn Copper Wire for Electrical PurposesASTM Standards:
B 276 Test Method for Apparent Porosity in Cemented Carbides
B 374 Terminology Relating to Electroplating
B 537 Practice for Rating of Electroplated Panels Subjected to Atmospheric Exposure
B 542 Terminology Relating to Electrical Contacts and Their Use
B 545 Specification for Electrodeposited Coatings of Tin
B 605 Specification for Electrodeposited Coatings of Tin-Nickel Alloy
B 650 Specification for Electrodeposited Engineering Chromium Coatings ofon Ferrous Substrates
B 689 Specification for Electroplated Engineering Nickel Coatings
B 733Specification for Autocatalytic Nickel-Phosphorous Coatings on Metals Specification for Autocatalytic (Electroless)
Nickel-Phosphorus Coatings on Metal
B 734 Specification for Electrodeposited Copper for Engineering Uses
B 735 Test Method for Porosity in Gold Coatings on Metal Substrates by Nitric Acid Vapor
B 741 Test Method for Porosity inIn Gold Coatings onOn Metal Substrates byBy Paper Electrography
B 798 Test Method for Porosity in Gold or Palladium Coatings on Metal Substrates by Gel-Bulk Electrography
B 799 Test Method for Porosity in Gold and Palladium Coatings by Sulfurous Acid/Sulfur-Dioxide Vapor
B 809Test Method for Porosity in Metallic Coatings by Humid Sulfur Vapor (“Flowers-of-Sulfur”) Test Method for Porosity
in Metallic Coatings by Humid Sulfur Vapor (Flowers-of-Sulfur)
This guide is under the jurisdiction ofASTM Committee B-8B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on General
Test Methods.
Current edition approved Jan. 15, 1993.Aug. 1, 2008. Published March 1993.September 2008. Originally published as B765–86.approved in 1986. Last previous edition
B765–86.approved in 2003 as B 765 – 93 (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 02.03.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.
B765–03 (2008)
TABLE 1 Applications of Standard Porosity Tests to Metallic Coatings (Section 6)
A
Substrate Metal Gold Silver Nickel Tin-Nickel Tin Tin-Lead Copper Palladium Chromium
B
Copper and Copper 6.1 , 6.2, 6.3A 6.4 6.4 6.4 6.4 . 6.2, 6.3A, 6.4, .
Alloys 6.4, 6.5 6.5
B
Nickel 6.1 , 6.2, 6.5 6.3A . . . . . 6.2, 6.3A, 6.5 .
Iron or Steel 6.6 . 6.6 6.3B, 6.6 6.3B, 6.6 6.3B, 6.6 6.6 . 6.6
Silver 6.4 . 6.4 6.4 6.4 6.4 . 6.4 .
A
The substrate may be the basis metal, an underplate, or both (see Note 1).
B
Thickness restrictions may apply.
TABLE 2 Applications of Tests for Gross Defects and Mechanical Damage (Section 7)
A
Substrate Metal Gold Nickel Tin-Nickel Tin Tin-Lead Palladium Silver
Copper and Copper 7.3, 7.5 7.3, 7.4 7.3 7.3 7.3 7.3, 7.5 7.5
Alloys
Nickel 7.5 . . . . 7.5 7.5
Iron or Steel 7.1 7.1 7.1 7.1 7.1 7.1 .
Aluminum . 7.2 . . . . .
A
The substrate may be the basis metal, an underplate, or both (see Note 1).
B 866 Test Method for Gross Defects and Mechanical Damage in Metallic Coatings by Polysulfide Immersion
B 877 Test Method for Gross Defects and Mechanical Damage in Metallic Coatings by the Phosphomolybdic Acid (PMA)
Method
3. Terminology
3.1 Definitions—Many terms used in this guide are defined in Terminology B 374 or B 542.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 porosity—for the purpose of this guide, porosity in a coating is defined as any hole, crack, or other defect that exposes
the underlying metal to the environment. —for the purpose of this guide, porosity in a coating is defined as any hole, crack, or
other defect that exposes the underlying metal to the environment. Differences between the major types of porosity are described
in Section 5.
3.2.2 underplate—a metallic coating layer between the basis metal and the topmost metallic coating. The thickness of an
underplating is usually greater than 1 µm, in contrast to a strike or flash, which are usually thinner.
4. Significance and Use
4.1 Porosity tests indicate the completeness of protection or coverage offered by the coating. When a given coating is known
to be protective when properly deposited, the porosity serves as a measure of the control of the process. The effects of substrate
finish and preparation, plating bath, coating process, and handling, may all affect the degree of imperfection that is measured.
NOTE 1—The substrate exposed by the pores may be the basis metal, an underplate, or both.
4.2 The tests in this guide involve corrosion reactions in which the products delineate pores in coatings. Since the chemistry
and properties of these products may not resemble those found in service environments, these tests are not recommended for
prediction of product performance unless correlation is first established with service experience.
5. Applications
5.1 From the viewpoint of both porosity testing and functional significance, it is useful to divide porosity into two broad
,
3 4
categories, namely intrinsic porosity and gross defects.
5.1.1 Intrinsic or normal porosity is due primarily to small deviations from ideal plating and surface preparation conditions.As
such, it will be present to some degree in all commercial thin platings and will generally follow an inverse relationship with
thickness. In addition, scanning electron microscope (SEM) studies have shown that the diameter of such pores at the plating
surface is of the order of micrometers, so that only small areas of underlying metal are exposed to the environment.
5.1.2 Gross defects, on the other hand, would result in comparatively large areas of exposed basis metal or underplating.
Examples of such defects are mechanical damage to the coating through mishandling or wear. Gross defects can also be found in
undamaged coatings in the form of networks of microcracks and as large as-plated pores—with diameters an order of magnitude
(or more) greater than intrinsic porosity. Such gross defects indicate such serious deviations from acceptable coating practice as
dirty substrates and contaminated or out-of-balance baths.
Annual Book of ASTM Standards, Vol 02.05.
Baker, R. G., Holden, C. A., and Mendizza, A., Proceedings of the American Electroplaters Society, Vol 50, 1963, p. 61.
Annual Book of ASTM Standards, Vol 03.04.
Krumbein, S. J., “The ASTM Approach to Porosity Testing,” Proc. 1991 International Technical Conf. of the American Electroplaters and Surface Finishers Soc.,
(SUR/FIN ’91), Toronto, 1991, pp. 527–536.
B765–03 (2008)
5.2 Intrinsic porosity and most types of gross defects are too small to be seen except at magnifications so high that a realistic
assessment of the overall coating surface in the functional areas of the part cannot be made. Instead, the presence and severity of
the porosity is normally determined by some type of pore-corrosion test that will magnify the pore sites by producing visible
reaction products in and around the pores or cracks. Tests for gross defects (Section 7), and especially for mechanical damage and
wear, are designed to be less severe. Such tests, however, may not detect a sizeable portion of the smaller (intrinsic) pores in a
coating. On the other hand, standard tests for intrinsic porosity (Section 6) will easily reveal the presence of gross defects as well.
5.3 Porosity tests are generally destructive in nature and are designed to assess the quality of the coating process in conjunction
with the substrate. Theref
...
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