ASTM_C_1282_-_08.pdf

Designation:C 1282 08Standard Test Method forDetermining the Particle Size Distribution of AdvancedCeramics by Centrifugal Photosedimentation1This standard is issued under the fixed designation C 1282;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers determination of the particlesize distribution of advanced ceramic powders specificallysilicon nitride and carbides,in the range of 0.1 to 20 m,having a median particle diameter from 0.5 to 5.0 m.1.2 The procedure described in this test method may beapplied successfully to other ceramic powders in this generalsize range,provided that appropriate dispersion procedures aredeveloped.It is the responsibility of the user to determine theapplicability of this test method to other materials.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.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-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2C 242 Terminology of Ceramic Whitewares and RelatedProducts3.Terminology3.1 DefinitionsRefer to Terminology C 242 for definitionsof terms used in this test method.4.Summary of Test Method4.1 A homogeneous aqueous dispersion of the powder isprepared.While kept in a thoroughly mixed condition,a smallaliquot is transferred to the analyzer sample cell,which isplaced in the instrument and subjected to a controlled centrifu-gal acceleration at a known or controlled temperature.Atpredetermined times related to the sedimentation of specificStokes diameters(Note 1),the optical absorbance is recordedand compared to the initial value to determine the fraction ofthe total sample that has sedimented a specific distance.Avolume-based size distribution is calculated from theabsorbance-time data.The results are reported as equivalentdiameter(spherical)(Note 2)since particles in these powdersare not truly spherical.NOTE1This diameter in m is referred to as D in the equation givenbelow.NOTE2Refer to Terminology C 242 for the ASTM definition of thisterm.Most equipment manufacturers refer to this as the equivalentspherical diameter.D2518h logX1X2ps pf!u2t3 108(1)where:h=viscosity of the fluid,cP,X1=distance from the middle of the centrifugal disc cell to the pointin the cell where sedimentation starts,X2=distance from the center of the centrifugal disc cell to the pointwhere the light beam intersects the particlet=time for the particle to settle,srs=particle density,g/cm3,rf=fluid density,g/cm3,andu=rotational angular velocity,rad/s.4.2 The instruments that have been found suitable for thistest method incorporate microcomputers that control instru-ment operation and perform all required data acquisition andcomputation functions.5.Significance and Use5.1 Manufacturers and users of advanced ceramic powderswill find this test method useful for determining the particlesize distribution of these materials for product specification,quality control,and research and development.6.Apparatus6.1 Centrifugal Particle Size Distribution AnalyzerTheanalyzer shall incorporate a centrifuge capable of subjecting anhomogeneous dispersion of the sample to centrifugal accelera-tion in specially designed sample cells.A collimated beam of1This test method is under the jurisdiction of ASTM Committee C28 onAdvanced Ceramics and is the direct responsibility of Subcommittee C28.03 onPhysical Properties and Performance.Current edition approved Jan.1,2008.Published January 2008.Originallyapproved in 1994.Last previous edition approved in 2006 as C 1282 00(2006).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.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.Copyright by ASTM Intl(all rights reserved);Thu Apr 16 08:44:25 EDT 2009Downloaded/printed byLaurentian University pursuant to License Agreement.No further reproductions authorized.visible light(either monochromatic or broad-band)shalltraverse the sample cell at a defined distance from the top of thecell.The change in photo-extinction resulting from sedimen-tation of the sample shall be measured by a photo-detector andappropriate electronic circuits and used to calculate thevolume-based size distribution of the sample.6.2 Ultrasonic Probe,consisting of a 200 to 300-W powerunit,ultrasonic transducer,and 13-mm(12-in.)diamete