ASTM A630-2003(2014) Standard Test Methods for Determination of Tin Coating Weights for Electrolytic Tin Plate《测定热浸电解镀锡板镀锡层重量的标准试验方法》.pdf

1、Designation: A630 03 (Reapproved 2014)Standard 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 revision,

2、 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 methods f

3、or 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 purpos

4、es 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 outlined in

5、Specification A624/A624M and Specification A626/A626M.1. Scope1.1 These test methods include four methods for the deter-mination of tin coating weights for electrolytic tin plate asfollows:Test Method SectionsABendix Test Method 3 to 9BConstant-Current, Electrolytic Test Method (Referee Method) 10 t

6、o 18CSellars Test Method 19 to 28DTitration Test Method 29 to 371.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard doe

7、s not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Stan

8、dards:2A599/A599M Specification for Tin Mill Products, Electro-lytic Tin-Coated, Cold-Rolled SheetA623 Specification for Tin Mill Products, General Require-mentsA623M Specification for Tin Mill Products, General Re-quirements MetricA624/A624M Specification for Tin Mill Products, Electro-lytic Tin Pl

9、ate, Single ReducedA626/A626M Specification for Tin Mill Products, Electro-lytic Tin Plate, Double ReducedD1125 Test Methods for Electrical Conductivity and Resis-tivity of WaterMETHOD ADETERMINATION OF THE TINCOATING WEIGHTS BY THE BENDIX TESTMETHOD3. Scope3.1 This test method covers the determinat

10、ion of tin coatingweights on steel plate.1These test methods are under the jurisdiction of ASTM Committee A01 onSteel, Stainless Steel and Related Alloys and are the direct responsibility ofSubcommittee A01.20 on Tin Mill Products.Current edition approved Oct. 1, 2014. Published November 2014. Origi

11、nallyapproved in 1968. Last previous edition approved in 2009 as A630 - 03(2009). DOI:10.1520/A0630-03R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standa

12、rds Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this 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

13、a tinplate anode in a dilute hydrochloric acid solution containing ameasured excess of standard potassium iodate-potassium io-dide solution. Excess iodine from the iodate-iodide solution isback titrated with standard sodium thiosulfate using a starchindicator.5. Apparatus35.1 The detinning cell cons

14、ists essentially of two cathodesof carbon rod, the sample that serves as an anode, and a beakerof dilute hydrochloric acid electrolyte. The carbon rods (6 by0.25 in. or 152 by 6.35 mm, encased in porous porcelainthimbles) are suspended from a suitable frame about 1 in. (25mm) apart. A small glass-en

15、closed magnet is attached to theframe in such a manner that it will hold the sample suspendedmidway between the two cathodes. A movable platform per-mits the beaker of electrolyte to be brought up around theassembly so that the sample will be completely immersed.5.2 Asource of direct current that ca

16、n be regulated to supplyup to 3 A at 3 to 5 V through the deplater is required.5.3 Although regular laboratory glassware can be used, it isadvisable to use automatic dispensing pipets or burets, amotor-driven stirrer for titrations, and a timing switch whenlarge numbers of determinations are to be m

17、ade.5.4 PrecautionsThe apparatus must be kept in continuousoperation to prevent iron in the solution adhering to the porouscells from oxidizing and subsequently liberating iodine fromthe potassium iodate-potassium iodide solution. If the instru-ment has been idle for some time, it is necessary to re

18、move theferric iron by running a disk of tinplate through the regularprocedure before test samples are run.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit

19、tee on Analytical Reagents of the American Chemical Societywhere such specifications are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 WaterDeionized or dis

20、tilled water having a volumeresistivity greater than 1 Mcm at 25C as determined byNonreferee Method of Test Methods D1125.6.3 Hydrochloric Acid (1.7 to 2.0 N)Add 1 part ofconcentrated hydrochloric acid (HCl, sp gr 1.19, 36.5 to38.0%) to 5 parts of water and mix well.6.4 Potassium Iodate-Potassium Io

21、dide, Standard Solution(0.0975 N)Dissolve 3.48 g of KIO3, 21.74 g of KI, and 1.21g of NaOH in 1 L of distilled water. Standardize as follows:Transfer 0.2700 g of National Bureau of Standards tin to a500-mL Erlenmeyer flask. Add 200 mL of HCl (1+1). Connectthe flask to a carbon dioxide (CO2) system a

22、nd displace the airin the flask with CO2. While continuing the flow of CO2, heatthe flask but do not boil violently. After the tin has dissolvedadd 0.5 g of antimony and2gofhigh-purity aluminum. Heatuntil the aluminum is completely dissolved and digest for anadditional 10 min. Cool the flask to room

23、 temperature inrunning water while maintaining an atmosphere of CO2.Disconnect from the CO2system and titrate with the KIO3-KIsolution 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 tite

24、r for above KIO3-KI solution, (grams of tin/mL),T = 17.28 = lb/base box (bb)/mL, for a 4-in.2(25.81-cm2)sample.6.5 Sodium Thiosulfate, Standard Solution (for coatingsover 0.50 lb/bb)Dissolve 15.11 g of Na2S2O35 H2O and 1.11g of NaOH in 1 litre of distilled water in a light-proof bottle.Allow this so

25、lution to age for 72 h, remix, and standardize asfollows: Connect the bottle to the Bendix apparatus and titrate20 mL of the standardized KIO3-KI solution with the thiosul-fate solution using the same procedure as is used for makingweight of coating determinations, but ignore the stripping unit.The

26、tin equivalent of the Na2S2O3solution in pounds per basebox is equal to: 20/AT17.28, where A = millilitres ofsodium thiosulfate solution used in titrating 20 mL of standardKIO3-KI solution. A chart can be prepared showing lb/bb/mLof thiosulfate.6.6 Sodium Thiosulfate, Standard Solution (for coatings

27、0.50 lb/bb and under)Dissolve 6.57 g of Na2S2O35 H2O and2.78 g of NaOH in 1 litre of distilled water in a light-proofbottle. Larger quantities in the same proportions may beprepared if desired. Allow that solution to age for 72 h, remix,and standardize by the same procedure used for the strongerNa2S

28、2O3solution but use only 10 mL of potassium iodate-potassium iodide solution.6.7 Starch SolutionHeat 200 mL of distilled water toboiling in a Florence flask and slowly add 2.5 g of solublestarch paste while the solution is agitated. Add the hot starchsolution to 500 mL of distilled water containing

29、2.5 g ofNaOH. Dilute to 1 L and thoroughly mix.7. Test Sample7.1 Tin plate samples for coating weight determinations areobtained by stamping disks 2.257 6 0.001 in. (57.33 6 0.02mm) in diameter which is equivalent to 4 in.2(25.81 cm2)of3Complete details and drawings of the apparatus are contained in

30、 U. S. PatentNo. 2,455,726 entitled “Method for Electrolytic Stripping and Determination ofPlating Metals.” A suitable commercial supplier of the apparatus has been found tobe the Wilkens-Anderson Company of Chicago.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Socie

31、ty, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.A

32、630 03 (2014)2area (8 in.2(52 cm2) of surface area). Recommended methodsof obtaining representative samples are described in the TinMill Products sections of the American Iron and Steel Insti-tutes Steel Products Manual.58. Procedure8.1 Make required electrical connections.8.2 Add HCl (1+1) to the p

33、orous tubes containing thecarbon cathodes.8.3 Suspend the sample disk of tin plate from the magneticholder.NOTE 1If it is desired to strip on one side only, mask the opposite sideand reduce the current to half its normal value. If a heavy oxide film hasdeveloped on the tin plate during storage, the

34、plate must be cathodicallycleaned prior to testing.8.4 Place a measured quantity of standardized KIO3-KIsolution into a 400-mL beaker (see 8.10). Simultaneously add250 mL of dilute HCl and mix thoroughly.8.5 Raise the beaker so that the sample and porous cells areimmersed.8.6 Turn on d-c current and

35、 adjust to give 0.5 A/in.2ofsample.8.7 Time for complete removal of tin (see 8.10).8.8 Remove the beaker and add approximately 5 mL ofstarch indicator solution.8.9 Titrate with standardized Na2S2O3solution to the dis-appearance of the blue color.8.10 The stripping times and amounts of KIO3-KI soluti

36、onto use are as follows:Amount ofStripping 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 toremove all of the tin. Results will be high by approximately0

37、01 lb/bb for each minute of over-stripping.9. Reproducibility of Results9.1 Arbitrary maximum spreads in intermill check testsshow the reproducibility of test results by the Bendix Methodto be as follows: 60.02 lb/bb for 0.25lb coatings, 60.03 lb/bbfor 0.75-lb coatings, and 60.04 lb/bb for 1.25-lb

38、coatings. Datahave not been developed for 0.10-lb coatings.METHOD BDETERMINATION OF THE TINCOATING WEIGHTS BY THE CONSTANTCURRENT, ELECTROLYTIC METHOD (REFEREEMETHOD)10. Scope10.1 This test method6may be used to determine not onlythe total tin coating weight but also to determine that part of thetin

39、 coating which is present as free tin and that part which ispresent in the alloyed form.11. Summary of Test Method11.1 In this test method, the tin is stripped from a sample oftin-plate anodically at constant current in an electrolyte of thehydrochloric acid. The potential difference developed betwe

40、enthe sample and a reference electrode is plotted against time ona strip chart recorder or an electric digital readout. The timerequired for stripping the free tin and alloyed tin, respectively,are read from the resulting chart (see Fig. 1) or a digitalreadout. Since the stripping current has been p

41、reset, the free-tinand alloy-tin coating weights are calculated by employingFaradays law of electrolysis.12. Calibration and Standardization12.1 Determine the weight loss of pure tin specimenselectrolyzed for a given time interval, expressing the results asmilligrams or pounds of tin per base box pe

42、r second.12.2 The test specimen should be a 4-in.2disk of pure tinapproximately 0.20 in. (5.1 mm) thick.12.3 The milliammeter should be frequently checked usinga precision milliammeter.13. Available Constant Current Procedures13.1 There are two commercially available constant current,electrolytic un

43、its that are in common use. Either of thefollowing, or equivalent equipment, can be used as an accept-able referee method:13.1.1 Willey and “Methods for Determination ofCoating Weights of Tin Plate,” American Iron and Steel Institute, December 1959,pp. 1926.7Available from Coulometric Systems, Bergh

44、oltz, OH.8Available from Products Distribution Service Division, Wilkens Anderson Co.,4525 West Division St., Chicago, IL 60651.A630 03 (2014)3acid. The potential difference developed between the sampleand a glass calomel reference electrode is plotted against timeon a strip chart recorder. The time

45、 required for stripping thefree tin and alloy tin, respectively are read from the resultingchart (see Fig. 1) or on an electronic digital readout. Since thestripping current is constant and preset, the free tin and alloytin coating weights are calculated by employing Faradays lawof electrolysis.14.2

46、 Significance and Use:14.2.1 The amount of tin coating is directly associated withthe economics of producing tinplate and the performance of thecontainer or part for which such plate is used. Therefore, thetest method was developed for accuracy and as a control. Theamount of tin combined in the allo

47、y layer is also essential asthe continuity and amount plays an important part in itsfunctional properties. This test method is so designed that thetin coating is determined on only one side of the specimen ata time. This is useful when determining tin coatings ondifferential tinplate.14.3 Apparatus:

48、14.3.1 This instrument (Model 8014) consists of anammeter, volt meter, constant current source and strip recorder.A cell and sample holder are provided.14.4 Reagents:14.4.1 Electrolyte1.0 N hydrochloric acid (HCl).14.5 Sample Size:14.5.1 Tinplate samples for coating weight determinationsare obtained

49、 by stamping discs 2.257 6 0.001 in. (57.33 60.02 mm) in diameter. This is equivalent to 4 in.2(25.81 cm2)of area of one side. Sampling procedures for tin coating weighttesting and applicable standards for the specific class designa-tion are outlined in Specifications, A624, A624M, A626, andA626M.14.6 Interferences:14.6.1 The distance of the cathode from the sample isimportant and should be 0.75 6 0.25 in. (1.90 6 0.64 cm).Also, it is important that the cathode be approximately thesame shape as the sample so that all parts of the anode areequidistant f