ASTM_D_4616_-_95_2013.pdf

Designation:D461695(Reapproved 2013)Standard Test Method forMicroscopical Analysis by Reflected Light andDetermination of Mesophase in a Pitch1This standard is issued under the fixed designation D4616;the number immediately following the designation indicates the 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()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers laboratory procedures for thepreparation of granular and melted samples for microscopicanalysis using reflected light to identify and estimate theamount and size of the mesophase.1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.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 to use.2.Referenced Documents2.1 ASTM Standards:2D329 Specification for AcetoneD1160 Test Method for Distillation of Petroleum Products atReduced PressureD2318 Test Method for Quinoline-Insoluble(QI)Content ofTar and PitchD3104 Test Method for Softening Point of Pitches(MettlerSoftening Point Method)D4296 Practice for Sampling PitchE11 Specification for Woven Wire Test Sieve Cloth and TestSievesE562 Test Method for Determining Volume Fraction bySystematic Manual Point Count3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 cenospheresusually a minor component of coal tarpitch.They are formed by the rapid pyrolysis of unconfinedcoal particles that are carried over from the coke oven to thetar.Microscopically,they appear like hollow spheres or seg-ments thereof(see Fig.1),and are typically sized from about10 to 500 m.In polarized light(crossed polarizers),acenosphere may be optically active.The size of the anisotropicpattern or mosaic depends upon the rank of the coal carbon-ized.Cenospheres are harder than the continuous phase andpolish in relief(see Fig.1).3.1.2 coke-oven-cokeusually a minor component of coaltar pitch.It originates in carry-over from the coke oven to thetar side.It differs from cenospheres only in terms of its shapeand porosity.Coke-oven-coke is angular and less porous.3.1.3 isotropic phaseusually the predominant,andcontinuous,phase.It is a complex mixture of organic aromaticcompounds composed mainly of carbon and hydrogen.Atroom temperature,the isotropic phase is a glass-like solid.It isoptically inactive in polarized light(see Fig.1 and Fig.2).3.1.4 mesophasean optically anisotropic liquid crystalcarbonaceous phase that forms from the parent liquor whenmolecular size,shape,and distribution are favorable.In theearly stages of its development,mesophase usually appears asspheroids.The planar molecules are lined up equatorially asshown schematically in Fig.3.This equatorial arrangementmay be distinguished in crossed polarized light.Under crossedpolarizers,the distinctive mesophase spheroids,with theircomplex extinction patterns shown in Fig.2,can be readilyseen.33.1.4.1 spheroidsAt magnifications of 400 and 500,theminimum spheroid size which can be resolved with confidenceis 4 m in diameter.At magnifications of 1000 to 1800,theminimum spheroid size that can be resolved with confidence isabout 2 m in diameter.Typically,the upper size may be 100m.Mesophase spheroids are relatively soft and do not formrelief structures(see Fig.4).Quinoline insoluble particles oftenaggregate at the interface between the continuous isotropicphase and mesophase.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.05 on Properties of Fuels,Petroleum Coke and Carbon Material.Current edition approved May 1,2013.Published August 2013.Originallyapproved in 1986.Last previous edition approved in 2008 as D4616 95(2008).DOI:10.1520/D4616-95R13.2For 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 website.3Amore complete discussion will be found in a paper by Honda,H.,Kimura,H.,and Sanada,Y.,“Changes of Pleochroism and Extinction Contours in CarbonaceousMesophase,”Carbon,9,1971,pp.695697.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.4.2 isotropic phaseThe isotropic phase is more solublethan the mesophase in solvents such as toluene.Solventetching is achieved by soaking the polished surface in toluenefor a few seconds,rinsing the surface with cold flowing water,FIG.1 Photomicrographs o