ASTM E634-2018 Standard Practice for Sampling of Zinc and Zinc Alloys for Analysis by Spark Atomic Emission Spectrometry.pdf

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1、Designation: E634 12E634 18Standard Practice forSampling of Zinc and Zinc Alloys for Analysis by SparkAtomic Emission Spectrometry1This standard is issued under the fixed designation E634; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi

2、sion, 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 practice covers the sampling of zinc and zinc alloys to obtain a sample suitable for quantitati

3、ve spark atomic emissionspectrochemical analysis. Included are procedures for obtaining representative samples from molten metal, from fabricated or castproducts that can be melted, and from other forms that cannot be melted.1.2 The values stated in SI units are to be regarded as standard. The value

4、s given in parentheses are for information only.1.3 This standard 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 safety, health, and healthenvironmental practices and determ

5、ine theapplicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations is

6、suedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Summary of Practice2.1 Molten metal representative of the furnace melt is poured into a mold to produce a chill-cast sample. The sample, whichmust represent the average composition, is machined to a specified shape to

7、 produce an acceptable surface for excitation.2.2 Fabricated or cast products are remelted and cast into molds or are excited directly without remelting.3. Significance and Use3.1 This practice, used in conjunction with an appropriate quantitative spark atomic emission spectrochemical method, issuit

8、able for use in manufacturing control, material or product acceptance, and development and research.4. Apparatus4.1 Ladle, of steel, designed to hold sufficient molten metal to completely fill the sample mold, with a handle of sufficient lengthto reach into a furnace, trough, pot, or crucible.NOTE 1

9、Pure zinc metal (Special High Grade) is sampled using a ceramic or graphite ladle, as the solubility of iron in Special High Grade Zinc issufficient to cause a measurable contamination.4.2 Sample Molds, designed to produce homogeneous chill-cast specimens having smooth surfaces, free from surface po

10、cketsand pores. The specimens shall be representative (in the region to be excited) of the product metal. The samples shall have aspectrochemical response similar to the standards used in preparing the analytical curves. This is ensured by casting standards andspecimens in the same manner. Also, the

11、 specimens shall have a repeatability of measurement for major elements fromexcitation-to-excitation with a relative error of no more than 2 %. Several types of molds have been found acceptable.4.2.1 Type A, Pin Mold (Fig. 1)This mold produces two diagonally cast pins with sprues at the top of the s

12、pecimens. The molddimensions are such as to produce pins approximately 100 mm (3.9 in.) in length by 11 mm (0.4 in.) in diameter. The mold is madeof steel or cast iron and weighs approximately 4.5 to 5.5 kg (10 to 12 lb). Pin specimens have been found to be very homogeneous.If properly prepared, the

13、se specimens provide very reliable results with only one burn. However, pin specimens must be reshapedfor each additional burn.1 This practice is under the jurisdiction of ASTM Committee E01 on Analytical Chemistry for Metals, Ores, and Related Materials and is the direct responsibility ofSubcommitt

14、ee E01.05 on Cu, Pb, Zn, Cd, Sn, Be, Precious Metals, their Alloys, and Related Metals.Current edition approved April 1, 2012Oct. 1, 2018. Published May 2012October 2018. Originally approved in 1978. Last previous edition approved in 20052012 asE634 05.E634 12. DOI: 10.1520/E0634-12.10.1520/E0634-18

15、.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 technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior ed

16、itions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.2.2 Type B, Book Mold (Fig. 2)This mold produ

17、ces a vertically cast disk with a sprue on the edge of the specimen. The molddimensions are such as to produce a disk of approximately 64 mm (2.5 in.) in diameter by 6 to 8 mm (0.2 to 0.3 in.) in thickness.A circular central recess, 15 to 25 mm (0.6 to 1.0 in.) in diameter, on one side of the specim

18、en facilitates machining of that sidein preparation for excitation. It also promotes more uniform freezing of the raised peripheral area. The mold is made of steel orcast iron and weighs approximately 2 to 3 kg (4 to 7 lb). This mold works well for high purity zinc grades, but with alloys maycause s

19、egregation due to solidification phenomena. Specimens should be excited only in the areas indicated in Fig. 3, and it maybe necessary to make several burns and report an average. The user is strongly cautioned to thoroughly investigate specimenhomogeneity for each alloy system to be analyzed.FIG. 1

20、Type A Mold and SpecimenFIG. 2 Type B Mold and SpecimenE634 1824.2.3 Type C, Center Pour Mold (Fig. 4)This mold produces a horizontally cast disk with a sprue over the center on the backside. The mold dimensions are such as to produce a disk approximately 64 mm (2.5 in.) in diameter by 8 mm (0.3 in.

21、) in thickness.A circular central recess, 10 to 20 mm (0.4 to 0.8 in.) in diameter, on one side of the specimen facilitates machining of that sidein preparation for excitation. It also promotes more uniform freezing of the raised peripheral area, but the corresponding raisedportion of the mold shall

22、 not be so large as to restrict the throat for the sprue. A slight taper, 1 to 2 deg, on the hinged portion ofthe mold facilitates opening when a specimen has been cast. The mold is made of steel or cast iron and weighs approximately 3.5to 4.5 kg (8 to 10 lb). The advantage of this mold is that the

23、specimen obtained may be excited around the entire annular area.However, as with the vertically cast disk specimens, although not as severe, segregation can be a problem. Therefore, it may benecessary to make several burns and report an average.4.2.4 Other MoldsMolds of different types, materials, a

24、nd dimensions may be used provided that the uniformity of thespecimens obtained is comparable to the uniformity of specimens obtained from Type A, B, or C molds. Further, the specimensshall have a spectrochemical response similar to the standards used for preparing the analytical curves.4.3 Lathe or

25、 Milling Machine, capable of machining a smooth flat surface.NOTE 2When using pin specimens, reproducibility of the exact pin shape is very important. To maintain the integrity of the pin shapes it may benecessary to equip a micrometer cross-fed lathe with a special pin-shaping tool.4.4 Cutting Tool

26、sEither alloy steel or cemented carbide is recommended.NOTE 1Shaded areas are acceptable for analysis.FIG. 3 Specimens from Type A, B, and C MoldsFIG. 4 Type C Mold and SpecimenE634 1835. Sampling5.1 Molten MetalWhen molten metal is sampled, the temperature shall be well above the point at which any

27、 solid phase canbe present. Using a clean ladle, push any dross away from the sampling area. Then dip the ladle sideways into the clear area, wellbelow the surface, and stir momentarily. Turn the ladle upright and quickly withdraw. Heating the ladle prevents metal freezing,while obtaining metal well

28、 beneath the surface minimizes the danger of inclusion of oxide. Unless the mold is already hot, castand discard a preliminary specimen. Remove any excess metal from the ladle, dip it into the molten metal as before, and fill themold using an even rate of pour so as to allow for the escape of air. D

29、o not dump the metal into the mold. Avoid overfilling thesprue or the mold may be difficult to open. Allow the metal to freeze without jarring. The cast surfaces of the specimen, uponremoval from the mold, shall be free from shrinkage, inclusions, cracks, or roughness.NOTE 3A change in the temperatu

30、re profile of the mold, caused by a significant change in the sampling rate, may result in different chill-castcharacteristics and poor repeatability. Therefore, it is recommended that the sampling schedule be considered when an analysis program is beingdeveloped. Also, experience has shown that pin

31、 specimens are much less sensitive than disk samples to temperature profile changes in the mold.5.2 Fabricated and Cast ProductsWhen the metal is in the wrought or cast form and a destructive test is practical, remelt arepresentative portion of the metal at a temperature well above the liquidus line

32、 on the phase diagram of the metal. The sampleis placed in a graphite or other inert crucible and heated in a laboratory electric furnace. The melt is then cast in the mold asoutlined in 5.1. If the sample is in the form of thin sheet, turnings, or other finely divided material, remove any coatings

33、or greasewith an appropriate solvent and press into a briquet before melting. Details of briquet size and formation are not critical to thesuccessful preparation of a melt. It is imperative that the specimen and the standards used in preparing the analytical curvesundergo the same sampling procedure

34、, that is, remelting, to ensure valid analyses. However, when possible, it is recommended thatanalytical methods involving dissolution of the metal be used in preference to the remelting of samples.6. Preparation of Specimens6.1 Chill-Cast Pins from Type A MoldCut off the sprues from the pins and ma

35、chine the sprue ends of both pins to the sameshape. Each time the pins are reshaped, about 3 mm (0.1 in.) of metal should be removed from the end of the pins. Then makea second cut to produce a surface at an angle of about 60 deg to the axis of the pin. Continue this cut until the flat end of the pi

36、nmeasures exactly 3 mm (0.1 in.) in diameter. The completed pin tip is a truncated cone with a 120-deg apex angle and a 3-mm(0.1-in.) diameter (Fig. 3). The machined surface shall be smooth and free from scuffs, pits, or inclusions. The ideal surface isneither polished nor visibly grooved, but shoul

37、d show a very fine tool pattern. More specifically, the ideal surface may be definedas approximately a 1.6 by 103-mm (63-in.) standard machine finish. A surface much finer or coarser may result in an analyticaldifference. Further, it is important that both specimens and standards have the same machi

38、ne finish. Pin specimens have been foundto be very homogeneous and can be excited over the entire length of the pin. However, it is recommended that the lower 13 mm(0.5 in.) of the pin specimen (Fig. 3) not be excited because of potential solidification effects.6.2 Chill-Cast Disk from Type B or C M

39、oldsCut off the sprue and machine the raised peripheral area surrounding the recessto a depth of 1 to 1.5 mm (0.04 to 0.06 in.) below the original surface. This depth is important because it corresponds to thecomposition on the phase diagram which represents the average composition of the entire dis

40、k and, in turn, the actual compositionof the melt. Any other depth may result in an invalid analysis. The machined surface shall be smooth, and free from scuffs, pits,or inclusions. The ideal surface is neither polished nor visibly grooved, but should show a very fine tool pattern. The ideal surface

41、may be defined as approximately a 1.6 by 103-mm (63-in.) standard machine finish. A surface much finer or much coarser mayresult in an analytical difference. It is also important that both specimens and standards have the same machine finish. A type Bdisk may be excited only in certain areas (Fig. 3

42、), while a Type C disk may be excited around the entire annular area. For bothtypes, the outer 5 mm (0.2 in.) to the edge and the inner region up to about a 12-mm (0.48-in.) radius should not be excited (Fig.3).6.3 Chill-Cast Specimens from Other Acceptable MoldsSince a mold of different dimensions

43、may result in a different freezingpattern, each type of mold shall be evaluated to determine the proper area and depth to machine the specimen to represent the truecomposition of the melt.6.4 Direct Excitation Without Casting a SpecimenIf the procedure outlined in Section 5 cannot be followed, only

44、approximateanalyses can be made. The specimen shall be massive enough to prevent undue heating and shall have a flat surface suitable forexcitation. Further, standards having a similar spectrochemical response shall be available. On sheet or plate specimens, machineoff about 0.8 mm (0.03 in.) or one

45、-fourth of the thickness, whichever is smaller. On thicker specimens, machine at least 1.3 mm(0.05 in.) below the original surface. Choose the location, depth, and number of areas to be analyzed to provide a representativeanalysis of the product.E634 1847. Keywords7.1 optical emission; sampling; spa

46、rk atomic emission; spectrochemical analysis; zinc and zinc alloysASTM 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 s

47、uch 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 comments are invit

48、ed 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 have not received a

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