ASTM B940-05(2009)e1

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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´1
Designation: B940 − 05(Reapproved 2009)
Standard Practice for
Testing Non-Chromate Coatings on Zinc and Cadmium
Surfaces
This standard is issued under the fixed designation B940; 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.
ε NOTE—The units statement in subsection (1.3) was added editorially in January 2010.
1. Scope 3.1.1.1 Discussion—In most instances, failure is defined as
the first appearance on significant surfaces of white corrosion
1.1 This practice covers a procedure for evaluating the
products visible to the unaided eye at normal reading distance,
protective value of chemical and electrochemical conversion
except that the presence of white corrosion products at sharp
coatingsproducedbynon-chromate(chromatebeingdefinedas
edges (for example, on threaded fasteners) and at junctions
a compound that has chromium in the plus six oxidation state,
between dissimilar metals should not be considered failure. In
and as such, chromium compounds in other oxidation states,
some instances, it may be desirable to regard the first appear-
suchasplusthree,shallnotbeexcluded)treatmentsofzincand
ance of red rust as failure.
cadmium surfaces.
3.1.2 significant surfaces—in general, significant surfaces
1.2 The protective value of a non-chromate coating is
are those surfaces that are visible and subject to corrosion or
usually determined by salt-spray test and by determining
wear, or both, except that surfaces that are normally difficult to
whether or not the coating possesses adequate abrasion resis-
coat by electroplating or mechanical deposition may be ex-
tance when applied for that purpose.
empt. The designation of significant surfaces may be indicated
1.3 The values stated in SI units are to be regarded as
on the drawing.
standard. No other units of measurement are included in this
4. Significance and Use
standard.
4.1 This practice is applicable to non-chromate coatings that
1.4 This standard does not purport to address all of the
are colorless, colored, electrochemically applied or non-
safety concerns, if any, associated with its use. It is the
electrochemically applied. The zinc or cadmium, or both, may
responsibility of the user of this standard to establish appro-
be electrodeposited, mechanically deposited, hot-dipped,
priate safety and health practices and determine the applica-
rolled, or in the form of castings.
bility of regulatory limitations prior to use.
4.2 Because of variables inherent in the salt-spray test
2. Referenced Documents
which may differ from one test cabinet to another, interpreta-
2.1 ASTM Standards:
tion of test results for compliance with expected performance
B117 Practice for Operating Salt Spray (Fog) Apparatus
should be specified by the purchaser.
4.3 Properties such as thickness, color, luster, and ability to
3. Terminology
provide good paint adhesion are not covered in this practice,
3.1 Descriptions of Terms:
nor are the chemical composition and the method of applica-
3.1.1 time to failure—time to failure will depend on the type
tion of these finishes.
of coating tested. The minimum expected protective value
obtainable in a given salt spray test is given in Appendix X2. 5. Conditioning
5.1 Aging—Before subjecting a non-chromate coating to
test, check with the chemical producer to determine if aging is
This practice is under the jurisdiction of ASTM Committee B08 on Metallic
an issue that needs to be considered.
and Inorganic Coatingsand is the direct responsibility of Subcommittee B08.07 on
Conversion Coatings
5.2 Preparation of Specimen—The test surface must be free
Current edition approved Sept. 1, 2009. Published January 2009. Originally
of fingerprints and other extraneous stains and must not be
approved in 2000. Last previous edition approved in 2005 as B940– 05. DOI:
10.1520/B0940-05R09E01.
cleaned except by gentle wiping with a clean, dry, soft cloth to
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
remove loose particles. Oily or greasy surfaces should not be
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
used for testing, and degreasing with organic solvents is not
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. recommended.
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