1、Designation: E 634 05Standard Practice forSampling of Zinc and Zinc Alloys for Optical EmissionSpectrometric Analysis1This standard is issued under the fixed designation E 634; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar 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 practice covers the sampling of zinc and zinc alloysto obtain a sample suitable for quantitative optical e
3、missionspectrochemical analysis. Included are procedures for obtain-ing representative samples from molten metal, from fabricatedor cast products that can be melted, and from other forms thatcannot be melted.1.2 The values stated in SI units are to be regarded as thestandard. The values given in par
4、entheses are 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 limitat
5、ions prior to use.2. Summary of Practice2.1 Molten metal representative of the furnace melt ispoured into a mold to produce a chill-cast sample. The sample,which must represent the average composition, is machined toa specified shape to produce an acceptable surface for excita-tion.2.2 Fabricated or
6、 cast products are remelted and cast intomolds or are excited directly without remelting.3. Significance and Use3.1 This practice, used in conjunction with an appropriatequantitative optical emission spectrochemical method, is suit-able for use in manufacturing control, material or productacceptance
7、, and development and research.4. Apparatus4.1 Ladle, of steel, designed to hold sufficient molten metalto completely fill the sample mold, with a handle of sufficientlength to reach into a furnace, trough, pot, or crucible.NOTE 1Pure zinc metal (Special High Grade) is sampled using aceramic or grap
8、hite ladle, as the solubility of iron in Special High GradeZinc is sufficient to cause a measurable contamination.4.2 Sample Molds, designed to produce homogeneous chill-cast specimens having smooth surfaces, free from surfacepockets and pores. The specimens shall be representative (inthe region to
9、be excited) of the product metal. The samplesshall have a spectrochemical response similar to the standardsused in preparing the analytical curves. This is ensured bycasting standards and specimens in the same manner. Also, thespecimens shall have a repeatability of measurement for majorelements fro
10、m excitation-to-excitation with a relative error ofno more than 2 %. Several types of molds have been foundacceptable.4.2.1 Type A, Pin Mold (Fig. 1)This mold produces twodiagonally cast pins with sprues at the top of the specimens.The mold dimensions are such as to produce pins approxi-mately 100 m
11、m (3.9 in.) in length by 11 mm (0.4 in.) indiameter. The mold is made of steel or cast iron and weighsapproximately 4.5 to 5.5 kg (10 to 12 lb). Pin specimens havebeen found to be very homogeneous. If properly prepared,these specimens provide very reliable results with only oneburn. However, pin spe
12、cimens must be reshaped for eachadditional burn.4.2.2 Type B, Book Mold (Fig. 2)This mold produces avertically cast disk with a sprue on the edge of the specimen.The mold dimensions are such as to produce a disk ofapproximately 64 mm (2.5 in.) in diameter by 6 to 8 mm (0.2to 0.3 in.) in thickness. A
13、 circular central recess, 15 to 25 mm(0.6 to 1.0 in.) in diameter, on one side of the specimenfacilitates machining of that side in preparation for excitation.It also promotes more uniform freezing of the raised peripheralarea. The mold is made of steel or cast iron and weighsapproximately 2 to 3 kg
14、 (4 to 7 lb). This mold works well forhigh purity zinc grades, but with alloys may cause segregationdue to solidification phenomena. Specimens should be excitedonly in the areas indicated in Fig. 3, and it may be necessary tomake several burns and report an average. The user is stronglycautioned to
15、thoroughly investigate specimen homogeneity foreach alloy system to be analyzed.4.2.3 Type C, Center Pour Mold (Fig. 4)This moldproduces a horizontally cast disk with a sprue over the centeron the back side. The mold dimensions are such as to producea disk approximately 64 mm (2.5 in.) in diameter b
16、y 8 mm (0.31This practice is under the jurisdiction of ASTM Committee E01 on AnalyticalChemistry for Metals, Ores and Related Materials and is the direct responsibility ofSubcommittee E01.05 on Cu, Pb, Zn, Cd, Sn, Be, TheirAlloys, and Related Metals.Current edition approved Oct. 1, 2005. Published N
17、ovember 2005. Originallyapproved in 1978. Last previous edition approved in 2001 as E 634 96 (2001).1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.in.) in thickness. A circular central recess, 10 to 20 mm (0.4 to0.8 in.) in diameter
18、, on one side of the specimen facilitatesmachining of that side in preparation for excitation. It alsopromotes more uniform freezing of the raised peripheral area,but the corresponding raised portion of the mold shall not be solarge as to restrict the throat for the sprue. A slight taper, 1 to2 deg,
19、 on the hinged portion of the mold facilitates openingwhen a specimen has been cast. The mold is made of steel orcast iron and weighs approximately 3.5 to 4.5 kg (8 to 10 lb).The advantage of this mold is that the specimen obtained maybe excited around the entire annular area. However, as with theve
20、rtically cast disk specimens, although not as severe, segre-gation can be a problem. Therefore, it may be necessary tomake several burns and report an average.4.2.4 Other MoldsMolds of different types, materials, anddimensions may be used provided that the uniformity of thespecimens obtained is comp
21、arable to the uniformity of speci-mens obtained from Type A, B, or C molds. Further, thespecimens shall have a spectrochemical response similar to thestandards used for preparing the analytical curves.4.3 Lathe or Milling Machine, capable of machining asmooth flat surface.FIG. 1 Type A Mold and Spec
22、imenFIG. 2 Type B Mold and SpecimenE634052NOTE 2When using pin specimens, reproducibility of the exact pinshape is very important. To maintain the integrity of the pin shapes it maybe necessary to equip a micrometer cross-fed lathe with a specialpin-shaping tool.4.4 Cutting ToolsEither alloy steel o
23、r cemented carbide isrecommended.5. Sampling5.1 Molten MetalWhen molten metal is sampled, thetemperature shall be well above the point at which any solidphase can be present. Using a clean ladle, push any dross awayfrom the sampling area. Then dip the ladle sideways into theclear area, well below th
24、e surface, and stir momentarily. Turnthe ladle upright and quickly withdraw. Heating the ladleprevents metal freezing, while obtaining metal well beneath thesurface minimizes the danger of inclusion of oxide. Unless themold is already hot, cast and discard a preliminary specimen.Remove any excess me
25、tal from the ladle, dip it into the moltenmetal as before, and fill the mold using an even rate of pour soas to allow for the escape of air. Do not dump the metal into themold. Avoid overfilling the sprue or the mold may be difficultto open. Allow the metal to freeze without jarring. The castsurface
26、s of the specimen, upon removal from the mold, shall befree from shrinkage, inclusions, cracks, or roughness.NOTE 3A change in the temperature profile of the mold, caused by asignificant change in the sampling rate, may result in different chill-castcharacteristics and poor repeatability. Therefore,
27、 it is recommended thatthe sampling schedule be considered when an analysis program is beingdeveloped. Also, experience has shown that pin specimens are much lesssensitive than disk samples to temperature profile changes in the mold.5.2 Fabricated and Cast ProductsWhen the metal is inthe wrought or
28、cast form and a destructive test is practical,remelt a representative portion of the metal at a temperatureNOTE 1Shaded areas are acceptable for analysis.FIG. 3 Specimens from Type A, B, and C MoldsFIG. 4 Type C Mold and SpecimenE634053well above the liquidus line on the phase diagram of the metal.T
29、he sample is placed in a graphite or other inert crucible andheated in a laboratory electric furnace. The melt is then cast inthe mold as outlined in 5.1. If the sample is in the form of thinsheet, turnings, or other finely divided material, remove anycoatings or grease with an appropriate solvent a
30、nd press into abriquet before melting. Details of briquet size and formationare not critical to the successful preparation of a melt. It isimperative that the specimen and the standards used in prepar-ing the analytical curves undergo the same sampling proce-dure, that is, remelting, to ensure valid
31、 analyses. However,when possible, it is recommended that analytical methodsinvolving dissolution of the metal be used in preference to theremelting of samples.6. Preparation of Specimens6.1 Chill-Cast Pins from Type A MoldCut off the spruesfrom the pins and machine the sprue ends of both pins to the
32、same shape. Each time the pins are reshaped, about 3 mm (0.1in.) of metal should be removed from the end of the pins. Thenmake a second cut to produce a surface at an angle of about 60deg to the axis of the pin. Continue this cut until the flat end ofthe pin measures exactly 3 mm (0.1 in.) in diamet
33、er. Thecompleted pin tip is a truncated cone with a 120-deg apex angleand a 3-mm (0.1-in.) diameter (Fig. 3). The machined surfaceshall be smooth and free from scuffs, pits, or inclusions. Theideal surface is neither polished nor visibly grooved, but shouldshow a very fine tool pattern. More specifi
34、cally, the idealsurface may be defined as approximately a 1.6 by 103-mm(63-in.) standard machine finish. A surface much finer orcoarser may result in an analytical difference. Further, it isimportant that both specimens and standards have the samemachine finish. Pin specimens have been found to be v
35、eryhomogeneous and can be excited over the entire length of thepin. However, it is recommended that the lower 13 mm (0.5in.) of the pin specimen (Fig. 3) not be excited because ofpotential solidification effects.6.2 Chill-Cast Disk from Type B or C MoldsCut off thesprue and machine the raised periph
36、eral area surrounding therecess to a depth of 1 to 1.5 mm (0.04 to 0.06 in.) below theoriginal surface. This depth is important because it correspondsto the composition on the phase diagram which represents theaverage composition of the entire disk and, in turn, the actualcomposition of the melt. An
37、y other depth may result in aninvalid analysis. The machined surface shall be smooth, andfree from scuffs, pits, or inclusions. The ideal surface is neitherpolished nor visibly grooved, but should show a very fine toolpattern. The ideal surface may be defined as approximately a1.6 by 103-mm (63-in.)
38、 standard machine finish. A surfacemuch finer or much coarser may result in an analyticaldifference. It is also important that both specimens andstandards have the same machine finish. A type B disk may beexcited only in certain areas (Fig. 3), while a Type C disk maybe excited around the entire ann
39、ular area. For both types, theouter 5 mm (0.2 in.) to the edge and the inner region up toabout 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 may result in a differentfreezing pattern, each type of mol
40、d shall be evaluated todetermine the proper area and depth to machine the specimento represent the true composition of the melt.6.4 Direct Excitation Without Casting a SpecimenIf theprocedure outlined in Section 5 cannot be followed, onlyapproximate analyses can be made. The specimen shall bemassive
41、 enough to prevent undue heating and shall have a flatsurface suitable for excitation. Further, standards having asimilar spectrochemical response shall be available. On sheetor plate specimens, machine off about 0.8 mm (0.03 in.) orone-fourth of the thickness, whichever is smaller. On thickerspecim
42、ens, machine at least 1.3 mm (0.05 in.) below theoriginal surface. Choose the location, depth, and number ofareas to be analyzed to provide a representative analysis of theproduct.7. Keywords7.1 optical emission; sampling; spectrochemical analysis;zinc and zinc alloysASTM International takes no posi
43、tion 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 riskof infringement of such rights, are entirely their own responsibili
44、ty.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 this standard or for additional standardsand should be addressed to AST
45、M 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 fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address
46、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).E634054
