1、Designation: D 6580 00 (Reapproved 2005)Standard 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 D 6580; the number immediately following the designation indicates the year
2、 oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination by differenti
3、alscanning calorimetry 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 ar
4、e for informationonly.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 and health practices and determine the applica-bility of regulatory limitations prior
5、to use.2. Referenced Documents2.1 ASTM Standards:2D 521 Test Methods for Chemical Analysis of Zinc-Dust(Metallic Zinc Powder)E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Summary of Test Method3.1 Samples of either zinc-dust pigment or of cured f
6、ilms 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 to 435C at 10C p
7、ermin, 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 This test method
8、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 MethodsD 521 is an appropriate method for analyzing zinc dust, but hasshortcomings when applied to samples of cured coatings.5. Interferences5.1 An
9、 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 high purity zincf
10、oil 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. Warning: Using thesame piece of foil more than once can result in i
11、naccurateresults, 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 distributethe sample even
12、ly 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, occurs during sta
13、bilization of the instrument1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications , and is the direct responsibilityof Subcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved July 1, 2005. P
14、ublished August 2005. Originallyapproved in 2000. Last previous edition approved in 2000 as D 6580 00.2For 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
15、Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.prior to the scan, or is negligible due to the small amount of binder presentin such coatings. If there is reason to suspect interference from t
16、he binder,the analyst may wish to test a blank sample of binder (with no zincpigment) to ensure that there is no effect on heat flow measurements.6. Apparatus6.1 Differential Scanning Calorimeter, either of the heatflux or power compensation type, capable of heating rates up toat least 10 6 1C/min a
17、nd of automatic recording of differencein heat input between the sample and a reference material, tothe required sensitivity and precision.6.2 Sample PansAluminum or other metal pans of highthermal conductivity are appropriate. A method or instrumentfor crimping the pans shut is also necessary.6.3 R
18、eference 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 at least 10 g.6.6 Mortar and PestleAn agate mortar and pe
19、stle, 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 standard calibrationprocedure, the instrument should be ca
20、librated using high-purity zinc-foil reference material. Approximately 3 to 6 mg ofreference material shall be weighed into a standard aluminumpan using a microbalance capable of weighing to at least 10 g.The pan shall then be crimped using an aluminum lid, and thereference sample analyzed in a sing
21、le dynamic step rangingfrom 370 to 435C at 10C per min, under a nitrogen purge.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 endothermictransition, in joules per gram, should be measu
22、red eitherelectronically or manually, and should be very close to that forpure zinc (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 3 to6 mg, to at least the nearest 10 g, into a standard aluminumpan, and cri
23、mp the pan shut. In the case of dried coating films,it is recommended that a razor blade or razor-blade type knifebe used to remove the coating from an area measuring at least12.7 mm by 12.7 mm (12 by12 in.) in size. This coating shouldthen be ground briefly, and approximately 3 to 6 mg weighedinto
24、a standard aluminum pan, which should then be crimpedshut.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 the melting (fusion) of zinc, in joules per gram, shouldthen
25、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 metallic zinc in the sample asfollows:Percent zinc metal 5X/108!
26、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,10.1.2 Description of instrument used for the test, and10.1.3 D
27、escription 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 E 691, as shown in Table1, where Sr and r are the within laboratory standard deviatio
28、nand 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 following criteria should be used forjudging the acceptabilit
29、y 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 (Multilaboratory)The coefficientof variation of results (each t
30、he average of three determina-tions), obtained by analysts in different laboratories has beenestimated to be 5.0 % relative. The 95 % limit for the differ-ence between two such averages is 13.9 % relative.11.2.3 BiasBias cannot be determined, as there are nostandard materials available.12. Keywords1
31、2.1 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 82.5222 2.0552 2.6453 5.7546 7.4068IV 69.3944 2.7797 3
32、.5989 7.7831 10.0768D 6580 00 (2005)2ASTM 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 validity of any such patent rights, and the ri
33、skof 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 comments are invited either for revision of th
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35、 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 multiple 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).D 6580 00 (2005)3
