1、Designation: D 5187 91 (Reapproved 2007)An American National StandardStandard Test Method forDetermination of Crystallite Size (Lcof Calcined PetroleumCoke by X-Ray Diffraction1This standard is issued under the fixed designation D 5187; the number immediately following the designation indicates the
2、year 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 of the me
3、ancrystallite thickness of a representative, pulverized sample ofcalcined petroleum coke by interpretation of a X-ray diffractionpattern produced through conventional X-ray scanning tech-niques.1.2 Calcined petroleum coke contains crystallites of differ-ent thicknesses. This test method covers the d
4、etermination ofthe average thickness of all crystallites in the sample byempirical interpretation of the X-ray diffraction pattern. Thecrystallite diameter (La) is not determined by this test method.1.3 The values stated in SI (metric) units are to be regardedas the standard. The inch-pound units gi
5、ven in parentheses areprovided for information purposes only.1.4 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-
6、bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 346 Practice for Collection and Preparation of CokeSamples for Laboratory AnalysisD 2013 Practice for Preparing Coal Samples for AnalysisD 2234/D 2234M Practice for Collection of a Gross Sampleof CoalD 4057 Pr
7、actice for Manual Sampling of Petroleum andPetroleum Products3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 crystallitesstacks of graphitic carbon platelets lo-cated parallel to one another.3.1.2 Lcthe mean or average thickness of crystallites in asample. It is expressed as a
8、 linear dimension in angstrom units,A(101nm).3.1.3 hkl(002)the Miller indices of the crystalline planesof graphite corresponding to a lattice spacing (d) of 3.35 .3.1.4 Qthe glancing angle produced when a parallel beamof uniform X-rays impinges upon a crystalline lattice. Thisangle is measured by th
9、e X-ray goniometer and is usuallyexpressed in 2Q.4. Summary of Test Method4.1 A packed sample pulverized to less than 75 m issubjected to a monochromatic X-ray beam and rotated toproduce a diffraction pattern under specific conditions. Thelocation and shape of the peak with hkl = (002) at d = 3.35;
10、Ais used to calculate the Lcby manual interpretation of the peakor by computer simulation.5. Significance and Use5.1 The crystallinity of petroleum coke, as reflected by theLcvalue, is a general measure of quality affecting suitability forend use and is a function of the heat treatment.5.2 The cryst
11、allite thickness is used to determine the extentof such heat treatment, for example, during calcination. Thevalue of the Lcdetermined is not affected by coke microporos-ity or the presence of foreign, non-crystalline materials such asdedust oil.6. Apparatus6.1 X-Ray Powder Diffractometer, equipped w
12、ith an X-raysource, a monochromator or filter for restricting the wave-length range, a sample holder, a radiation detector, a signalprocessor, and readout (chart or computer memory). Thediffractometer must be capable of rate scanning at 1 perminute or incrementally step scanning at 0.2 per step.6.2
13、Sample Holders, as specified by the manufacturer of thediffractometer that enables packing of a pulverized sample ofsufficient thickness to expose a level, smooth surface to theX-ray beam.6.3 Briquetting Press, capable of generating pressures up to10 000 psi (69 MPa).6.4 Compressible Aluminum Caps,
14、used as a support forproducing a briquetted sample.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.05 on Properties of Fuels, Petroleum Coke and Carbon Material.Current edition approved May 1, 2
15、007. Published June 2007. Originallypublished in 1991. Last previous edition approved in 2002 as D 518791 (2002).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
16、 standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.5 Silicon or Quartz Sample, available from NationalInstitute of Standards and Technology (NIST).7. Reagents and Materials7.1 Purity
17、 of ReagentsReagent grade chemicals shall beused in all tests. It is intended that all reagents shall conform tothe specifications of the Committee on Analytical Reagents ofthe American Chemical Society where such specifications areavailable.3Other grades may be used, provided it is firstascertained
18、 that the reagent is of sufficiently high purity topermit its use without lessening the accuracy of the determi-nation.7.2 Acetone.7.3 Polyethylene Glycol, (approximate molecular weight of200).7.4 Binding AgentPrepare a 15 mass % solution ofpolyethylene glycol and acetone by adding 15 g of polyethyl
19、-ene glycol to 85 g of acetone.8. Sample Preparation8.1 For recommended practices for obtaining, handling andpreparing coke samples, refer to Test Methods D 2013 andD 2234 and Practices D 346 and D 4057. The equipment andprocedures for crushing and dividing are also described inthese test methods.8.
20、2 Reduce and divide the gross sample to obtain a labora-tory analysis sample.8.3 Divide, by riffling, a minimum of 100 g from thelaboratory analysis sample.8.4 Crush 100 g of the test sample such that 98 % will passthrough a 75 m (No. 200) sieve.8.5 TechniquesAny of the following techniques can beus
21、ed for packing the sample into the X-ray diffractometerspecimen holder:8.5.1 Back Fill TechniquePut the window on a glass slide(Slide 1) and transfer sufficient quantities of sample into thewindow. Work the sample towards the corners of the holder byuse of a glass slide or spatula. Press down using
22、a flat glassslide and scrape off any excess material. Place a glass slide(Slide 2) on top of the sample and secure with tape. RemoveSlide 1 to expose a flat, smooth surface before inserting into thediffractometer for analysis.8.5.2 Front Fill TechniquePlace a confining ring over theround sample hold
23、er and fill the holder cavity and ring withsample. The ring will initially overfill the sample holder. Workthe sample into the entire cavity and ring. Scrape the excess offwith a glass plate or spatula. Press down using a flat glass slide.Remove any excess material on the front face of the holder.Re
24、press the sample with the glass slide while turning clockwiseand anti-clockwise. Continue until the sample is level with theholder face. Place the sample in diffractometer holder.8.5.3 Side Loading TechniquePack the sample followingthe procedure used by the National Institute of Standards andTechnol
25、ogy and the Joint Committee on Powder DiffractionStandards to prepare standard powder diffraction patterns.4Clamp a glass slide over the top face to form a temporarycavity wall. With the holder in a vertical position, drift thepowdered sample into the end opening. If necessary, use acardboard pusher
26、 cut to fit the cavity to lightly compress thesample so it will remain in the cavity. Return the holder to ahorizontal position and carefully remove the glass slide. Placethe sample in diffractometer holder.8.5.4 Briquetting TechniqueWeigh out 4.0 g of the sampleonto a watch glass and pipette exactl
27、y 3 mL of the bindingagent onto the sample and mix thoroughly with a spatula. Placethe sample under an infrared heat lamp and allow the acetoneto evaporate. Typically, about 1 or 2 min will be required toeliminate the acetone odor from sample. Break up the cakedsample with a spatula and transfer to
28、an aluminum cap whosediameter is compatible with the sample holder of the diffrac-tometer. Place the cap in a briquetting press and press at7000 psi (48 MPa). Transfer the pelletized sample to thesample holder and insert into the diffractometer for analysis.9. Calibration9.1 Calibration consists of
29、ensuring that the diffractometeris in correct mechanical and optical alignment and intensitieshave been maximized through the procedures described in theinstrument manufacturers documentation. This is best accom-plished by a service engineer or in-house technician who hasbeen well instructed in the
30、correct alignment proceduressuggested by the manufacturer.9.2 Proper angles and intensities are monitored by a refer-ence material such as NIST silicon and corrective actions takenif necessary.10. Procedure10.1 Prepare and operate the diffractometer in accordancewith the manufacturers instructions.
31、Once established, closelycontrol all instrumental parameters to ensure repeatable analy-ses.10.2 Place the packed sample in the instruments sampleholder and energize the X-ray source.10.3 Obtain a diffraction pattern rate scanned at 1/min orstep scanned at 0.2/step over the range of 14 to 34 2Q.Reco
32、rd the data either on a strip chart recorder scanning at1/min or through computer software designed to read andstore the angular and intensity measurements.10.4 For manual interpretation from a strip chart recording,refer to Fig. 1.10.4.1 Determine the average low and high background(Points A and B,
33、 respectively) on the diffraction scan andconnect them with a straight line.10.4.2 Construct Line CD parallel to AB and going throughthe apex of the peak at point G (hkl = 002 at 3.35A). Drawthe line such that if the peak is irregular it will pass through theaverage of the irregularities.3“Reagent C
34、hemicals, American Chemical Society Specification.” AmericanChemical Society, Washington, D.C. For suggestions on the testing of reagents notlisted by the American Chemical Society, see “Analar Standards for LaboratoryU.K. Chemicals,” BDH Ltd., Poole, Dorset, and the “United States Pharamacopeia.”4M
35、cMurdie, et al., “Methods of Producing X-Ray Diffraction Powder Diffrac-tions,” Powder Diffraction, Vol 1, No. 1, March 1986.D 5187 91 (2007)210.4.3 Determine the full width half maximum (FWHM) ofthe peak by measuring the vertical distance between CD andAB. Construct Line EF such that it intersects
36、the peak at halfof its maximum value. The points at which EF intersects thepeak are 2Q1and 2Q2, respectively.10.5 For computer simulation based on the intensities re-corded at 0.2 intervals, produce a mathematical representationof the diffraction curve. Determine the baseline, peak, peakheight, and
37、half peak height to produce the half peak heightangles, 2Q1and 2Q2, as above.11. Calculation11.1 Determine the following parameter:Dpo 5 2sin Q2 sin Q1!/l (1)where:l = the wavelength of the target material of the X-raytube expressed in angstrom units,Q1= the angle at the half peak intensity (2Q1/2)
38、width onthe low side, andQ2= the angle at the half peak intensity (2Q2/2) width onthe high side.NOTE 1The latter calculations were derived from the Scherrer equa-tion:Lc5 Kl!/b cos Q! (2)where:K = an arbitrary constant that is equivalent to 0.89 for Lc,l = wavelength of the source radiation measured
39、 inangstroms,b = line breadth of the pure diffraction peak measured inradians, andQ = angular location of the peak maximum (2Q/2) mea-sured in degrees.11.2 Determine the mean crystallite height by:Lc5 0.89/Dpo (3)NOTE 2The above calculation makes the assumption that the true linewidth is equal to th
40、e measured width, the contribution of instrumental linebroadening is negligible.12. Report12.1 Report the mean crystallite thickness to the first deci-mal as Lc= xx.x angstroms ().13. Precision and Bias513.1 The precision of this test method as determined by thestatistical examination of inter-labor
41、atory test results in whichone operator in ten laboratories made duplicate analysis oneach of six materials is as follows:13.1.1 RepeatabilityThe difference between successiveresults by the same operator using the same apparatus underconstant operating conditions on identical test materials will, in
42、the long run, in normal and correct operation of the testmethod, exceed the following value only in one case in twenty:Repeatability = 0.021Xwhere:X = the average of two results in angstroms.13.1.2 ReproducibilityThe difference between two singleand independent results obtained by different operator
43、s work-ing in different laboratories on identical test materials will, inthe long run, in normal and correct operation of the testmethod, exceed the following values only in one case intwenty:Reproducibility = 0.11Xwhere:X = the average of two results in angstroms.13.2 BiasSince there is no accepted
44、 reference materialsuitable for determining the bias for the procedure in this testmethod for measuring crystallinity of petroleum coke, bias hasnot been determined.14. Keywords14.1 crystallinity; Lc; petroleum coke; X-ray diffraction5The values in the statements were determined in a cooperative pro
45、gramfollowing RR:D02-1007. Supporting data have been filed at ASTM InternationalHeadquarters. Request RR:D02-1280.FIG. 1 Typical Diffraction Scan of Petroleum CokeD 5187 91 (2007)3ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item m
46、entionedin 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 responsibility.This standard is subject to revision at any time by the responsible technical committ
47、ee 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 ASTM International Headquarters. Your comments will receive careful consideration at a meet
48、ing 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 shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, P
49、O 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 5187 91 (2007)4
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