ASTM A630-98
(Test Method)Standard Test Methods for Determination of Tin Coating Weights for Electrolytic Tin Plate
Standard Test Methods for Determination of Tin Coating Weights for Electrolytic Tin Plate
SCOPE
1.1 These test methods include four methods for the determination of tin coating weights for electrolytic tin plate as follows: Test Method Sections A-Bendix Test Method 3 to 9 B-Constant-Current, Electrolytic Test Method (Referee Method) 10 to 22 C-Sellar's Test Method 23 to 32 D-Titration Test Method 33 to 41
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety problems, 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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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Designation: A 630 – 98
Standard Test Methods for
Determination of Tin Coating Weights for Electrolytic Tin
Plate
This standard is issued under the fixed designation A 630; 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.
INTRODUCTION
Four test methods for determination of tin coating weights are described. These are typical methods
and represent those most commonly used in the tin plate industry. Publication of these test methods
is not intended to preclude the use of any other methods such as X-ray fluorescence measurement
systems for control purposes by the consumer or supplier. However, in case of dispute, the referee
method is to be used to determine conformance to Specification A 624/A 624M and Specification
A 626/A 626M.
Sampling procedures for tin coating-weight testing and applicable standards for the specific class
designation are outlined in Specification A 624/A 624M and Specification A 626/A 626M.
1. Scope A 599/A 599M Specification for Tin Mill Products, Elec-
trolytic Tin-Coated, Cold-Rolled Sheet
1.1 These test methods include four methods for the deter-
A 623 Specification for Tin Mill Products, General Require-
mination of tin coating weights for electrolytic tin plate as
ments
follows:
A 623M Specification for Tin Mill Products, General Re-
Test Method Sections
quirements (Metric)
A—Bendix Test Method 3 to 9
B—Constant-Current, Electrolytic Test Method (Referee Method) 10 to 18
A 624/A 624M Specification for Tin Mill Products, Electro-
C—Sellar’s Test Method 19 to 28
lytic Tin Plate, Single Reduced
D—Titration Test Method 29 to 37
A 626/A 626M Specification for Tin Mill Products, Electro-
lytic Tin Plate, Double Reduced
1.2 The values stated in inch-pound units are to be regarded
D 1125 Test Methods for Electrical Conductivity and Re-
as the standard. The values given in parentheses are for
sistivity of Water
information only.
1.3 This standard does not purport to address all of the
METHOD A—DETERMINATION OF THE TIN
safety concerns, if any, associated with its use. It is the
COATING WEIGHTS BY THE BENDIX TEST
responsibility of the user of this standard to establish appro-
METHOD
priate safety and health practices and determine the applica-
3. Scope
bility of regulatory limitations prior to use.
3.1 This test method covers the determination of tin coating
2. Referenced Documents
weights on steel plate.
2.1 ASTM Standards:
4. Summary of Test Method
4.1 The procedure involves dissolution of tin from a tin
plate anode in a dilute hydrochloric acid solution containing a
These test methods are under the jurisdiction of ASTM Committee A-1 on
Steel, Stainless Steel and Related Alloys, and are the direct responsibility of
Subcommittee A01.20 on Tin Plate.
Current edition approved March 10, 1998. Published November 1998. Originally Annual Book of ASTM Standards, Vol 01.06.
published as A 630 – 68. Last previous edition A 630 – 91 (Reapproved 1997). Annual Book of ASTM Standards, Vol 11.01.
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.
A 630–98
measured excess of standard potassium iodate-potassium io- 500-mL Erlenmeyer flask. Add 200 mL of HCl (1+1). Connect
dide solution. Excess iodine from the iodate-iodide solution is the flask to a carbon dioxide (CO ) system and displace the air
back titrated with standard sodium thiosulfate using a starch in the flask with CO . While continuing the flow of CO , heat
2 2
indicator. the flask but do not boil violently. After the tin has dissolved
add 0.5 g of antimony and2gof high-purity aluminum. Heat
5. Apparatus
until the aluminum is completely dissolved and digest for an
5.1 The detinning cell consists essentially of two cathodes additional 10 min. Cool the flask to room temperature in
of carbon rod, the sample that serves as an anode, and a beaker running water while maintaining an atmosphere of CO .
of dilute hydrochloric acid electrolyte. The carbon rods (6 by Disconnect from the CO system and titrate with the KIO -KI
2 3
0.25 in. or 152 by 6.35 mm, encased in porous porcelain solution using starch as an indicator. Calculate the tin titer, T,
thimbles) are suspended from a suitable frame about 1 in. (25 as follows:
mm) apart. A small glass-enclosed magnet is attached to the
T 5 A/B
frame in such a manner that it will hold the sample suspended
where:
midway between the two cathodes. A movable platform per-
A = tin used (0.2700 g),
mits the beaker of electrolyte to be brought up around the
B = KIO -KI solution used for titration, mL, and
assembly so that the sample will be completely immersed. 3
T = tin titer for above KIO -KI solution, (grams of tin/mL),
5.2 A source of direct current that can be regulated to supply 3
2 2
T = 17.28 = lb/base box (bb)/mL, for a 4-in. (25.81-cm )
up to 3 A at 3 to 5 V through the deplater is required.
sample.
5.3 Although regular laboratory glassware can be used, it is
6.5 Sodium Thiosulfate, Standard Solution (for coatings
advisable to use automatic dispensing pipets or burets, a
over 0.50 lb/bb)—Dissolve 15.11 g of Na S O ·5 H O and
motor-driven stirrer for titrations, and a timing switch when 2 2 3 2
1.11 g of NaOH in 1 litre of distilled water in a light-proof
large numbers of determinations are to be made.
bottle. Allow this solution to age for 72 h, remix, and
5.4 Precautions—The apparatus must be kept in continuous
standardize as follows: Connect the bottle to the Bendix
operation to prevent iron in the solution adhering to the porous
apparatus and titrate 20 mL of the standardized KIO -KI
cells from oxidizing and subsequently liberating iodine from 3
solution with the thiosulfate solution using the same procedure
the potassium iodate-potassium iodide solution. If the instru-
as is used for making weight of coating determinations, but
ment has been idle for some time, it is necessary to remove the
ignore the stripping unit. The tin equivalent of the Na S O
2 2 3
ferric iron by running a disk of tinplate through the regular
solution in pounds per base box is equal to: 20/A 3 T 3 17.28,
procedure before test samples are run.
where A = millilitres of sodium thiosulfate solution used in
6. Reagents titrating 20 mL of standard KIO -KI solution. A chart can be
prepared showing lb/bb/mL of thiosulfate.
6.1 Purity of Reagents—Reagent grade chemicals shall be
6.6 Sodium Thiosulfate, Standard Solution (for coatings
used in all tests. Unless otherwise indicated, it is intended that
0.50 lb/bb and under)—Dissolve 6.57 g of Na S O ·5 H O and
all reagents shall conform to the specifications of the Commit-
2 2 3 2
2.78 g of NaOH in 1 litre of distilled water in a light-proof
tee on Analytical Reagents of the American Chemical Society
bottle. Larger quantities in the same proportions may be
where such specifications are available. Other grades may be
prepared if desired. Allow that solution to age for 72 h, remix,
used, provided it is first ascertained that the reagent is of
and standardize by the same procedure used for the stronger
sufficiently high purity to permit its use without lessening the
Na S O solution but use only 10 mL of potassium iodate-
accuracy of the determination. 2 2 3
potassium iodide solution.
6.2 Water—Deionized or distilled water having a volume
6.7 Starch Solution—Heat 200 mL of distilled water to
resistivity greater than 1 MV·cm at 25°C as determined by
Nonreferee Method of Test Methods D 1125. boiling in a Florence flask and slowly add 2.5 g of soluble
starch paste while the solution is agitated. Add the hot starch
6.3 Hydrochloric Acid (1.7 to 2.0 N)—Add 1 part of
concentrated hydrochloric acid (HCl, sp gr 1.19, 36.5 to solution to 500 mL of distilled water containing 2.5 g of
NaOH. Dilute to 1 L and thoroughly mix.
38.0%) to 5 parts of water and mix well.
6.4 Potassium Iodate-Potassium Iodide, Standard Solution
(0.0975 N)—Dissolve 3.48 g of KIO , 21.74 g of KI, and 1.21 7. Test Sample
g of NaOH in 1 L of distilled water. Standardize as follows:
7.1 Tin plate samples for coating weight determinations are
Transfer 0.2700 g of National Bureau of Standards tin to a
obtained by stamping disks 2.257 6 0.001 in. (57.33 6 0.02
2 2
mm) in diameter which is equivalent to 4 in. (25.81 cm of
2 2
area (8 in. (52 cm ) of surface area). Recommended methods
Complete details and drawings of the apparatus are contained in U. S. Patent
of obtaining representative samples are described in the Tin
No. 2,455,726 entitled “Method for Electrolytic Stripping and Determination of
Mill Products sections of the American Iron and Steel Insti-
Plating Metals.” A suitable commercial supplier of the apparatus has been found to
be the Wilkens-Anderson Company of Chicago.
tute’s Steel Products Manual.
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, Available from the American Iron and Steel Institute, 150 E. 42nd St., New
MD. York, NY.
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.
A 630–98
8. Procedure 11. Summary of Test Method
8.1 Make required electrical connections. 11.1 In this test method, the tin is stripped from a sample of
8.2 Add HCl (1+1) to the porous tubes containing the tin-plate anodically at constant current in an electrolyte of the
carbon cathodes. hydrochloric acid. The potential difference developed between
8.3 Suspend the sample disk of tin plate from the magnetic the sample and a reference electrode is plotted against time on
holder. a strip chart recorder or an electric digital readout. The time
required for stripping the free tin and alloyed tin, respectively,
NOTE 1—If it is desired to strip on one side only, mask the opposite side
are read from the resulting chart (see Fig. 1) or a digital
and reduce the current to half its normal value. If a heavy oxide film has
readout. Since the stripping current has been preset, the free-tin
developed on the tin plate during storage, the plate must be cathodically
and alloy-tin coating weights are calculated by employing
cleaned prior to testing.
Faraday’s law of electrolysis.
8.4 Place a measured quantity of standardized KIO -KI
solution into a 400-mL beaker (see 8.10). Simultaneously add
12. Calibration and Standardization
250 mL of dilute HCl and mix thoroughly.
12.1 Determine the weight loss of pure tin specimens
8.5 Raise the beaker so that the sample and porous cells are
electrolyzed for a given time interval, expressing the results as
immersed.
2 milligrams or pounds of tin per base box per second.
8.6 Turn on d-c current and adjust to give 0.5 A/in. of
12.2 The test specimen should be a 4-in. disk of pure tin
sample.
approximately 0.20 in. (5.1 mm) thick.
8.7 Time for complete removal of tin (see 8.10).
12.3 The milliammeter should be frequently checked using
8.8 Remove the beaker and add approximately 5 mL of
a precision milliammeter.
starch indicator solution.
8.9 Titrate with standardized Na S O solution to the dis-
2 2 3
13. Available Constant Current Procedures
appearance of the blue color.
13.1 There are two commercially available constant current,
8.10 The stripping times and amounts of KIO -KI solution
electrolytic units that are in common use. Either of the
to use are as follows:
following, or equivalent equipment, can be used as an accept-
Amount of
able referee method:
Stripping KIO -KI
Product Time, s Solution, mL
13.1.1 Willey & Kunze Coulometric Test Method—Supplier
Electrolytic 100 90 20
will provide set up, start up and running procedures.
Electrolytic 75 75 20
13.1.2 The Stannomatic Test Method—Supplier will provide
Electrolytic 50 60 10
Electrolytic 25 60 10
set up, start up and running procedures.
Electrolytic 10 45 10
14. Willey & Kunze Coulometric Test Method
Stripping time should not be longer than is required to
remove all of the tin. Results will be high by approximately
14.1 In this test method, the tin is electrolytically removed
2 2
0.01 lb/bb for each minute of over-stripping.
from a 4 in. (25.807 cm ) circular sample of tinplate anodically
at constant current in an electrolyte of 1.0 N hydrochloric acid.
9. Reproducibility of Results
The potential difference developed between the sample and a
glass calomel reference electrode is plotted against time on a
9.1 Arbitrary maximum spreads in intermill check tests
show the reproducibility of test results by the Bendix Method strip chart recorder. The time required for stripping the free tin
and alloy tin, respectively are read from the resulting chart (see
to be as follows: 60.02 lb/bb for 0.25 lb coatings, 60.03 lb/bb
Fig. 1) or on an electronic digital readout. Since the stripping
for 0.75-lb coatings, and 60.04 lb/bb for 1.25-lb coatings. Data
current is constant and preset, the free tin and alloy tin coating
have not been developed for 0.10-lb coatings.
weights are calculated by employing Faraday’s law of elec-
METHOD B—DETERMINATION OF THE TIN
trolysis.
COATING WEIGHTS BY THE CONSTANT 14.2 Significance and Use:
CURRENT, ELECTROLYTIC METHOD (REFEREE
14.2.1 The amount of tin coating is directly associated with
METHOD) the economics of producing tinplate and the performance of the
container or part for which such plate is used. Therefore, the
10. Scope
test method was developed for accuracy and as a control. The
amount of tin combined in the alloy layer is also essential as
10.1 This test method may be used to determine not only
the continuity and amount plays an important part in its
the total tin coating weight but also to determine that part of the
functional properties. This test method is so designed that the
tin coating which is present as free tin and that part which is
tin coating is determined on only one side of the specimen at
present in the alloyed form.
a time. This is useful when determining tin coatings on
differential tinplate.
See Kunze, C. T., and Wille
...
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