1、Designation: D6580 17Standard Test Method forThe Determination of Metallic Zinc Content in Both ZincDust Pigment and in Cured Films of Zinc-Rich Coatings1This standard is issued under the fixed designation D6580; the number immediately following the designation indicates the year oforiginal adoption
2、 or, in the case of revision, 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.1. Scope1.1 This test method covers the determination by differentialscanning calorimetr
3、y of the metallic zinc content of bothzinc-dust pigment, and of dried films of zinc-rich coatings.This test method is applicable to both inorganic and organiczinc-rich coatings1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly
4、.1.3 This standard does 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, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to us
5、e.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers
6、to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D521 Test Methods for Chemical Analysis of Zinc Dust(Metallic Zinc Powder)E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Summary of Test Method3.1 Samples of either zinc-dust pigme
7、nt or of cured films ofzinc-rich coatings are ground in a mortar and pestle, thencarefully weighed into standard differential scanning calorim-etry (DSC) sample pans. The pans are then crimped shut, andanalyzed in a differential scanning calorimeter in a singledynamic heating step, ranging from 370
8、to 435C at 10C permin, under a nitrogen purge. The percent metallic zinc in thesample is determined by measuring the energy associated withthe endothermic peak near 419C caused by the melting of themetallic zinc, and comparing this value to the heat of fusion ofpure zinc.4. Significance and Use4.1 T
9、his test method is useful for determining the amount ofmetallic zinc in zinc dust pigment, and also in dried films ofboth inorganic and organic zinc-rich coatings. Test MethodsD521 is an appropriate method for analyzing zinc dust, but hasshortcomings when applied to samples of cured coatings.5. Inte
10、rferences5.1 An increase or decrease in heating rate from thosespecified may slightly alter the results. However, the variationwould be expected to be minimal, so long as the zinc referencestandard and the samples are subjected to the same heatingrate.5.2 Daily calibration of the calorimeter with hi
11、gh purity zincfoil results in improved results. Reagent grade zinc granules orzinc powder are of insufficient purity to properly calibrate theinstrument. Furthermore, the high purity-zinc foil should onlybe used one time as a calibration standard. WarningUsingthe same piece of foil more than once ca
12、n result in inaccurateresults, due to oxidation of the zinc at the high temperatures inthe calorimeter, coupled with the alloying effects of zinc withthe aluminum sample pans.5.3 Important steps in achieving accurate and reproducibleresults are very gentle tapping of the pan in order to distributeth
13、e sample evenly over the bottom of the pan, and carefulplacement of the pan lid to avoid expulsion of the fine powderduring crimping.NOTE 1Round-robin testing has shown no evidence that pyrolysis ofthe binder interferes with the measurement of the heat of fusion. Eitherpyrolysis does not occur, occu
14、rs during stabilization of the instrumentprior to the scan, or is negligible due to the small amount of binder presentin such coatings. If there is reason to suspect interference from the binder,the analyst may wish to test a blank sample of binder (with no zinc1This test method is under the jurisdi
15、ction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved Dec. 1, 2017. Published January 2018. Originallyapproved in 2000. Last previous edi
16、tion approved in 2009 as D6580 00 (2009).DOI: 10.1520/D6580-17.2For 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 standards Document Summary page onthe ASTM websit
17、e.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of Int
18、ernational Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1pigment) to ensure that there is no effect on heat flow measurements.6. Apparatus6.1 Differential Scanning Calorimeter, either of the heat fluxor power compensation ty
19、pe, capable of heating rates up to atleast 10 6 1C/min and of automatic recording of difference inheat input between the sample and a reference material, to therequired sensitivity and precision.6.2 Sample PansAluminum or other metal pans of highthermal conductivity are appropriate. A method or inst
20、rumentfor crimping the pans shut is also necessary.6.3 Reference MaterialHigh purity-zinc foil suitable forcalibration of DSC instruments can be obtained from severalinstrument manufacturers.6.4 Nitrogen, or other inert gas supply, for blanketing thesample.6.5 Microbalance, capable of measuring to a
21、t least 10 g.6.6 Mortar and PestleAn agate mortar and pestle, ofdiameter approximately 29 mm (112 in.) has been foundsatisfactory.7. Calibration7.1 The instrument should be calibrated for heat flow asdescribed in the manufacturers instruction manual. In additionto, or as part of the manufacturers st
22、andard calibrationprocedure, the instrument should be calibrated using high-purity zinc-foil reference material. Approximately 2.8 to 3.0mg of reference material shall be weighed into a standardaluminum pan using a microbalance capable of weighing to atleast 10 g. The pan shall then be crimped using
23、 an aluminumlid, and the reference sample analyzed in a single dynamic stepranging from 370 to 435C at 10C per min, under a nitrogenpurge.7.2 When analyzed as just described, the reference sampleof zinc foil will give rise to an endothermic peak due to thefusion of zinc near 419C. The area under the
24、 endothermictransition, in joules per gram, should be measured eitherelectronically or manually, and should be within 2 J/g of purezinc (108 J/g).8. Procedure8.1 In the case of pigment samples, after thoroughly agitat-ing the container in which the sample is contained, weigh 2.8to 3.0 mg, to at leas
25、t the nearest 10 g, into a standardaluminum pan, and crimp the pan shut. In the case of driedcoating films, it is recommended that a razor blade or razor-blade type knife be used to remove the coating from an areameasuring at least 12.7 mm by 12.7 mm (12 by12 in.) in size.This coating should then be
26、 ground briefly, and approximately2.8 to 3.0 mg weighed into a standard aluminum pan, whichshould then be crimped shut.8.2 The sample should be analyzed in a singe dynamic stepranging from 370 to 435C at 10C per min, under a nitrogenpurge. The area under the endothermic transition correspond-ing to
27、the melting (fusion) of zinc, in joules per gram, shouldthen be determined in the same fashion as described for thezinc foil reference standard. Triplicate analyses should beperformed, and the results should be averaged to obtain theaverage heat of fusion.9. Calculation9.1 Calculate the percent meta
28、llic zinc in the sample asfollows:Percent zinc metal 5 X/108!100 (1)where:X = measured heat of fusion of sample, in joules/gram.10. Report10.1 Report the following information:10.1.1 Complete identification and description of the mate-rial tested, including source and manufacturers code, ifknown,10.
29、1.2 Description of instrument used for the test, and10.1.3 Description of calibration procedure.11. Precision and Bias11.1 PrecisionAn interlaboratory evaluation of this testmethod with three laboratories and four materials resulted inthe following statistics, from Practice E691, as shown in Table1,
30、 where Sr and r are the within laboratory standard deviationand repeatability and SR and R are the multi-laboratorystandard deviation and reproducibility: Materials I and IIrepresent two inorganic zinc-rich coatings, while III and IVrepresent two organic zinc rich coatings.11.2 Based on this, the fo
31、llowing criteria should be used forjudging the acceptability of results:11.2.1 Repeatability (Single Analyst)The standard devia-tion for a single determination has been estimated to be 2.8 %relative. The 95 % limit for the difference between two suchruns is 7.8 % relative.11.2.2 Reproducibility (Mul
32、tilaboratory)The coefficientof variation of results (each the average of threedeterminations), obtained by analysts in different laboratorieshas been estimated to be 5.0 % relative. The 95 % limit for thedifference between two such averages is 13.9 % relative.11.2.3 BiasBias cannot be determined, as
33、 there are nostandard materials available.12. Keywords12.1 differential scanning calorimetry; metallic zinc; zincdust pigment; zinc-rich primersTABLE 1 Summary of Interlaboratory Precision DataMaterials Average Sr SR r RI 84.1000 1.9156 3.9497 5.3636 11.0591II 71.8264 1.7122 4.8757 4.7943 13.6520III
34、 82.5222 2.0552 2.6453 5.7546 7.4068IV 69.3944 2.7797 3.5989 7.7831 10.0768D6580 172ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the
35、 validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your
36、 comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments
37、have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multi
38、ple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 173
