1、Designation: A630 03 (Reapproved 2014)A630 16Standard Test Methods forDetermination of Tin Coating Weights for Electrolytic TinPlate1This standard is issued under the fixed designation A630; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript 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.INTRODUCTIONFour test me
3、thods for determination of tin coating weights are described. These are typical methodsand represent those most commonly used in the tin plate industry. Publication of these test methodsis not intended to preclude the use of any other methods such as X-ray fluorescence measurementsystems for control
4、 purposes by the consumer or supplier. However, in case of dispute, the refereemethod is to be used to determine conformance to Specification A624/A624M and SpecificationA626/A626M.Sampling procedures for tin coating-weight testing and applicable standards for the specific classdesignation are outli
5、ned in Specification A624/A624M and Specification A626/A626M.1. Scope1.1 These test methods include four methods for the determination of tin coating weights for electrolytic tin plate as follows:Test Method SectionsABendix Test Method 3 to 9BConstant-Current, Electrolytic Test Method (Referee Metho
6、d) 10 to 18CSellars Test Method 19 to 28DTitration Test Method 29 to 371.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only and are not considered standard.1.3 This sta
7、ndard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 AS
8、TM Standards:2A599/A599M Specification for Tin Mill Products, Electrolytic Tin-Coated, Cold-Rolled SheetA623 Specification for Tin Mill Products, General RequirementsA623M Specification for Tin Mill Products, General Requirements MetricA624/A624M Specification for Tin Mill Products, Electrolytic Tin
9、 Plate, Single ReducedA626/A626M Specification for Tin Mill Products, Electrolytic Tin Plate, Double ReducedD1125 Test Methods for Electrical Conductivity and Resistivity of WaterMETHOD ADETERMINATION OF THE TIN COATING WEIGHTS BY THE BENDIX TEST METHOD3. Scope3.1 This test method covers the determi
10、nation of tin coating weights on steel plate.1 These test methods are under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and are the direct responsibility of SubcommitteeA01.20 on Tin Mill Products.Current edition approved Oct. 1, 2014May 1, 2016. Published Nov
11、ember 2014September 2016. Originally approved in 1968. Last previous edition approved in 20092014as A630 - 03(2009).(2014). DOI: 10.1520/A0630-03R14.10.1520/A0630-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Bo
12、ok of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be techn
13、ically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this
14、standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Test Method4.1 The procedure involves dissolution of tin from a tin plate anode in a dilute hydrochloric acid solution containing a measuredexcess of standard potas
15、sium iodate-potassium iodide solution. Excess iodine from the iodate-iodide solution is back titrated withstandard sodium thiosulfate using a starch indicator.5. Apparatus35.1 The detinning cell consists essentially of two cathodes of carbon rod, the sample that serves as an anode, and a beaker ofdi
16、lute hydrochloric acid electrolyte. The carbon rods (6 by 0.25 in. or 152 by 6.35 mm, encased in porous porcelain thimbles) aresuspended from a suitable frame about 1 in. (25 mm) (25 mm) apart. A small glass-enclosed magnet is attached to the frame insuch a manner that it will hold the sample suspen
17、ded midway between the two cathodes. A movable platform permits the beakerof electrolyte to be brought up around the assembly so that the sample will be completely immersed.5.2 A source of direct current that can be regulated to supply up to 3 A at 3 to 5 V through the deplater is required.5.3 Altho
18、ugh regular laboratory glassware can be used, it is advisable to use automatic dispensing pipets or burets, amotor-driven stirrer for titrations, and a timing switch when large numbers of determinations are to be made.5.4 PrecautionsThe apparatus must be kept in continuous operation to prevent iron
19、in the solution adhering to the porous cellsfrom oxidizing and subsequently liberating iodine from the potassium iodate-potassium iodide solution. If the instrument has beenidle for some time, it is necessary to remove the ferric iron by running a disk of tinplate through the regular procedure befor
20、e testsamples are run.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society wheresuch specifications
21、 are available.4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination.6.2 WaterDeionized or distilled water having a volume resistivity greater than 1 Mcm at 25C as determined b
22、y NonrefereeMethod of Test Methods D1125.6.3 Hydrochloric Acid (1.7 to 2.0 N)Add 1 part of concentrated hydrochloric acid (HCl, sp gr 1.19, 36.5 to 38.0%) to 5 partsof water and mix well.6.4 Potassium Iodate-Potassium Iodide, Standard Solution (0.0975 N)Dissolve 3.48 g of KIO3, 21.74 g of KI, and 1.
23、21 g ofNaOH in 1 L of distilled water. Standardize as follows: Transfer 0.2700 g of National Bureau of Standards tin to a 500-mLErlenmeyer flask. Add 200 mL of HCl (1+1). Connect the flask to a carbon dioxide (CO2) system and displace the air in the flaskwith CO2. While continuing the flow of CO2, h
24、eat the flask but do not boil violently. After the tin has dissolved add 0.5 g ofantimony and 2 g of high-purity aluminum. Heat until the aluminum is completely dissolved and digest for an additional 10 min.Cool the flask to room temperature in running water while maintaining an atmosphere of CO2. D
25、isconnect from the CO2 systemand titrate with the KIO3-KI solution using starch as an indicator. Calculate the tin titer, T, as follows:T 5 A/Bwhere:A = tin used (0.2700 g),B = KIO3-KI solution used for titration, mL, andT = tin titer for above KIO3-KI solution, (grams of tin/mL),T = 17.28 = lb/base
26、 box (bb)/mL, for a 4-in.2 (25.81-cm2) sample.6.5 Sodium Thiosulfate, Standard Solution (for coatings over 0.50 lb/bb)Dissolve 15.11 g of Na2S2O35 H2O and 1.11 g ofNaOH in 1 litre of distilled water in a light-proof bottle. Allow this solution to age for 72 h, remix, and standardize as follows:Conne
27、ct the bottle to the Bendix apparatus and titrate 20 mL of the standardized KIO3-KI solution with the thiosulfate solutionusing the same procedure as is used for making weight of coating determinations, but ignore the stripping unit. The tin equivalentof the Na2S2O3 solution in pounds per base box i
28、s equal to: 20/A T 17.28, where A = millilitres of sodium thiosulfate solutionused in titrating 20 mL of standard KIO3-KI solution. A chart can be prepared showing lb/bb/mL of thiosulfate.6.6 Sodium Thiosulfate, Standard Solution (for coatings 0.50 lb/bb and under)Dissolve 6.57 g of Na2S2O35 H2O and
29、 2.78g of NaOH in 1 litre of distilled water in a light-proof bottle. Larger quantities in the same proportions may be prepared if desired.3 Complete details and drawings of the apparatus are contained in U. S. Patent No. 2,455,726 entitled “Method for Electrolytic Stripping and Determination of Pla
30、tingMetals.” A suitable commercial supplier of the apparatus has been found to be the Wilkens-Anderson Company of Chicago.4 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Che
31、mical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.A630 162Allow that solution to age for 72 h, remix, and standardize by the same procedure u
32、sed for the stronger Na2S2O3 solution but useonly 10 mL of potassium iodate-potassium iodide solution.6.7 Starch SolutionHeat 200 mL of distilled water to boiling in a Florence flask and slowly add 2.5 g of soluble starch pastewhile the solution is agitated. Add the hot starch solution to 500 mL of
33、distilled water containing 2.5 g of NaOH. Dilute to 1 Land thoroughly mix.7. Test Sample7.1 Tin plate samples for coating weight determinations are obtained by stamping disks 2.257 6 0.001 in. (57.33 6 0.02 mm)in diameter which is equivalent to 4 in.2 (25.81 cm2) of area (8 in.2 (52 cm2) of surface
34、area). Recommended methods of obtainingrepresentative samples are described in the Tin Mill Products sections of the American Iron and Steel Institutes Steel ProductsManual.58. Procedure8.1 Make required electrical connections.8.2 Add HCl (1+1) to the porous tubes containing the carbon cathodes.8.3
35、Suspend the sample disk of tin plate from the magnetic holder.NOTE 1If it is desired to strip on one side only, mask the opposite side and reduce the current to half its normal value. If a heavy oxide film hasdeveloped on the tin plate during storage, the plate must be cathodically cleaned prior to
36、testing.8.4 Place a measured quantity of standardized KIO3-KI solution into a 400-mL beaker (see 8.10). Simultaneously add 250 mLof dilute HCl and mix thoroughly.8.5 Raise the beaker so that the sample and porous cells are immersed.8.6 Turn on d-c current and adjust to give 0.5 A/in.2 of sample.8.7
37、Time for complete removal of tin (see 8.10).8.8 Remove the beaker and add approximately 5 mL of starch indicator solution.8.9 Titrate with standardized Na2S2O3 solution to the disappearance of the blue color.8.10 The stripping times and amounts of KIO3-KI solution to use are as follows:Amount ofStri
38、pping KIO3-KIProduct Time, s Solution, mLElectrolytic 100 90 20Electrolytic 75 75 20Electrolytic 50 60 10Electrolytic 25 60 10Electrolytic 10 45 10Stripping time should not be longer than is required to remove all of the tin. Results will be high by approximately 0.01 lb/bbfor each minute of over-st
39、ripping.9. Reproducibility of Results9.1 Arbitrary maximum spreads in intermill check tests show the reproducibility of test results by the Bendix Method to be asfollows: 60.02 lb/bb for 0.25lb coatings, 60.03 lb/bb for 0.75-lb coatings, and 60.04 lb/bb for 1.25-lb coatings. Data have notbeen develo
40、ped for 0.10-lb coatings.METHOD BDETERMINATION OF THE TIN COATING WEIGHTS BY THE CONSTANT CURRENT,ELECTROLYTIC METHOD (REFEREE METHOD)10. Scope10.1 This test method6 may be used to determine not only the total tin coating weight but also to determine that part of the tincoating which is present as f
41、ree tin and that part which is present in the alloyed form.11. Summary of Test Method11.1 In this test method, the tin is stripped from a sample of tin-plate anodically at constant current in an electrolyte of thehydrochloric acid. The potential difference developed between the sample and a referenc
42、e electrode is plotted against time on a5 Available from American Iron and Steel Institute (AISI), 1140 Connecticut Ave., NW, Suite 705, Washington, DC 20036, http:/www.steel.org.6 See Kunze, C. T., and Willey, A. R., “Electrolytic Determination of Tin and Tin-Iron Alloy Coating Weights on Tin Plate
43、,” Journal, Electrochemical Society, Vol 99,No. 9, September 1952, pp. 354359; and “Methods for Determination of Coating Weights of Tin Plate,” American Iron and Steel Institute, December 1959, pp. 1926.A630 163strip chart recorder or an electric digital readout. The time required for stripping the
44、free tin and alloyed tin, respectively, are readfrom the resulting chart (see Fig. 1) or a digital readout. Since the stripping current has been preset, the free-tin and alloy-tincoating weights are calculated by employing Faradays law of electrolysis.12. Calibration and Standardization12.1 Determin
45、e the weight loss of pure tin specimens electrolyzed for a given time interval, expressing the results as milligramsor pounds of tin per base box per second.12.2 The test specimen should be a 4-in.2 disk of pure tin approximately 0.20 in. (5.1 mm) thick.12.3 The milliammeter should be frequently che
46、cked using a precision milliammeter.13. Available Constant Current Procedures13.1 There are two commercially available constant current, electrolytic units that are in common use. Either of the following,or equivalent equipment, can be used as an acceptable referee method:13.1.1 Willey “r” is the in
47、terval representing the critical difference between two test results for the same material, obtained by the sameoperator using the same equipment on the same day in the same laboratory.EReproducibility Limit (R) The maximum difference between two results, obtained under reproducibility conditions, t
48、hat is accepted as plausible due to random causesunder normal and correct operation of the test.A630 166lb/bb for 0.50-lb coatings and 60.02 lb/bb for 1.25-lb coatings.METHOD CDETERMINATION OF THE TIN THE TIN COATING WEIGHTS BY THE SELLARSTHE SELLARS METHOD19. Scope19.1 This test method covers the d
49、etermination of the total weight of tin carried by a unit area of tinplate.20. Summary of Test Method20.1 The tinplate sample is dissolved in hydrochloride acid. The tin goes into the solution as stannous chloride. Accidental airoxidation of the tin from the stannous to the stannic form is prevented by completing the analysis under an atmosphere of carbondioxide.20.2 The tin is titrated with a standard iodide-iodate solution, using starch as an indicator.21. Significance and Use21.1 This test method covers determination of the total tin in t
