ASTM D6580-00(2009)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D6580 − 00 (Reapproved 2009)
Standard Test Method for
The Determination of Metallic Zinc Content in Both Zinc
Dust Pigment and in Cured Films of Zinc-Rich Coatings
This standard is issued under the fixed designation D6580; 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 the endothermic peak near 419°C caused by the melting of the
metallic zinc, and comparing this value to the heat of fusion of
1.1 Thistestmethodcoversthedeterminationbydifferential
pure zinc.
scanning calorimetry of the metallic zinc content of both
zinc-dust pigment, and of dried films of zinc-rich coatings.
4. Significance and Use
This test method is applicable to both inorganic and organic
zinc-rich coatings 4.1 This test method is useful for determining the amount of
metallic zinc in zinc dust pigment, and also in dried films of
1.2 The values stated in SI units are to be regarded as the
both inorganic and organic zinc-rich coatings. Test Methods
standard. The values given in parentheses are for information
D521 is an appropriate method for analyzing zinc dust, but has
only.
shortcomings when applied to samples of cured coatings.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Interferences
responsibility of the user of this standard to establish appro-
5.1 An increase or decrease in heating rate from those
priate safety and health practices and determine the applica-
specified may slightly alter the results. However, the variation
bility of regulatory limitations prior to use.
would be expected to be minimal, so long as the zinc reference
standard and the samples are subjected to the same heating
2. Referenced Documents
rate.
2.1 ASTM Standards:
5.2 Dailycalibrationofthecalorimeterwithhighpurityzinc
D521 Test Methods for Chemical Analysis of Zinc Dust
foil results in improved results. Reagent grade zinc granules or
(Metallic Zinc Powder)
zinc powder are of insufficient purity to properly calibrate the
E691 Practice for Conducting an Interlaboratory Study to
instrument. Furthermore, the high purity-zinc foil should only
Determine the Precision of a Test Method
be used one time as a calibration standard. Warning—Using
the same piece of foil more than once can result in inaccurate
3. Summary of Test Method
results, due to oxidation of the zinc at the high temperatures in
3.1 Samples of either zinc-dust pigment or of cured films of
the calorimeter, coupled with the alloying effects of zinc with
zinc-rich coatings are ground in a mortar and pestle, then
the aluminum sample pans.
carefully weighed into standard differential scanning calorim-
5.3 Important steps in achieving accurate and reproducible
etry (DSC) sample pans. The pans are then crimped shut, and
results are very gentle tapping of the pan in order to distribute
analyzed in a differential scanning calorimeter in a single
the sample evenly over the bottom of the pan, and careful
dynamic heating step, ranging from 370 to 435°C at 10°C per
placement of the pan lid to avoid expulsion of the fine powder
min, under a nitrogen purge. The percent metallic zinc in the
during crimping.
sample is determined by measuring the energy associated with
NOTE 1—Round-robin testing has shown no evidence that pyrolysis of
the binder interferes with the measurement of the heat of fusion. Either
pyrolysis does not occur, occurs during stabilization of the instrument
This test method is under the jurisdiction of ASTM Committee D01 on Paint
prior to the scan, or is negligible due to the small amount of binder present
and Related Coatings, Materials, andApplications and is the direct responsibility of
in such coatings. If there is reason to suspect interference from the binder,
Subcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.
the analyst may wish to test a blank sample of binder (with no zinc
Current edition approved June 1, 2009. Published June 2009. Originally
pigment) to ensure that there is no effect on heat flow measurements.
approved in 2000. Last previous edition approved in 2005 as D6580 – 00 (2005).
DOI: 10.1520/D6580-00R09.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 6. Apparatus
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.1 Differential Scanning Calorimeter , either of the heat
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. fluxorpowercompensationtype,capableofheatingratesupto
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D6580 − 00 (2009)
at least 10 6 1°C/min and of automatic recording of difference zinc foil reference standard. Triplicate analyses should be
in heat input between the sample and a reference material, to performed, and the results should be averaged to obtain the
the required sensitivity and precision. average heat of fusion.
6.2 Sample Pans— Aluminum or other metal pans of high
9. Calculation
thermal conductivity are appropriate. A method or instrument
9.1 Calculate the percent metallic zinc in the sample as
for crimping the pans shut is also necessary.
follows:
6.3
...