1、Designation: E2980 15Standard Test Methods forEstimating Average Particle Size of Powders Using AirPermeability1This standard is issued under the fixed designation E2980; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、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. Scope*1.1 These test methods use air permeability to determine anenvelope-specific surface area and its associated averageequiv
3、alent spherical diameter (from 0.2 to 75 m) of powders.Two test methods are described: One test method for inorganicmaterials (Test Method 1), and another test method for organicmaterials (Test Method 2). The values obtained are notintended to be absolute but are generally useful on a relativebasis
4、for control purposes.1.2 UnitsWith the exception of the values for density andthe mass used to determine density, for which the use of thegram per cubic centimetre (g/cm3) and gram (g) units is thelongstanding industry practice; and the units for pressure, cmH2Oalso long-standing practice; the value
5、s in SI units are tobe regarded as 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 regulat
6、ory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B330 Test Methods for Estimating Average Particle Size ofMetal Powders and Related Compounds Using Air Per-meabilityB859 Practice for De-Agglomeration of Refractory MetalPowders and Their Compounds Prior to Particle SizeAnalysis
7、E29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE1638 Terminology Relating to Sieves, Sieving Methods,and Screening MediaE2589 Terminology Relating to Nonsieving Methods ofPowder Characterization2.2 ISO Documents:3ISO 10070 Metallic Powders: Determin
8、ations of Envelope-Specific Surface Area from Measurements of the Perme-ability to Air of a Powder Bed Under Steady-State FlowConditions3. Terminology3.1 DefinitionsMany terms used in this test method aredefined in Terminologies E1638 and E2589.3.2 Definitions of Terms Specific to This Standard:3.2.
9、1 air permeability, nmeasurement of air pressure dropacross a packed bed of powder.3.2.2 average particle size, nfor the purposes of these testmethods only, an estimate of the equivalent average sphericalparticle diameter, calculated from the measured envelope-specific surface area, assuming that al
10、l the powder particles arespherical and that all are exactly the same size.3.2.3 de-agglomeration, nprocess used to break up ag-glomerates of particles.3.2.4 envelope-specific surface area, nspecific surfacearea of a powder as determined by gas permeametry inaccordance with ISO 10070.3.2.5 MIC Sub-S
11、ieve AutoSizer (MIC SAS), na commer-cially available permeability instrument for measuringenvelope-specific surface area and estimating average particlesize from 0.2 to 75 m.3.2.6 porosity of a bed of powder, nratio of the volume ofthe void space in the powder bed to that of the overall volumeof the
12、 powder bed.4. Significance and Use4.1 These test methods provide procedures for determiningthe envelope-specific surface area of powders, from which iscalculated an “average” particle diameter, assuming the par-ticles are monosize, smooth surface, nonporous, spherical1These test methods are under t
13、he jurisdiction of ASTM Committee E29 onParticle and Spray Characterization and is the direct responsibility of SubcommitteeE29.02 on Non-Sieving Methods.Current edition approved Dec. 1, 2015. Published January 2016. Originallyapproved in 2014. Last previous edition approved in 2014 as E2980 14. DOI
14、:10.1520/E2980-15.2For 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.3Available from American National Standards
15、 Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1particles. For this reason, values ob
16、tained by these test methodswill be reported as an average particle size. The degree ofcorrelation between the results of these test methods and thequality of powders in use will vary with each particularapplication and has not been fully determined.4.2 These test methods are generally applicable to
17、 allpowders, including metals (see Test Methods B330 for specificmetal powder requirements), ceramics, and organic materials,for particles having diameters between 0.2 and 75 m. Theyshould not be used for powders composed of particles whoseshape is too far from equiaxed - that is, flakes or fibers.
18、In thesecases, it is permissible to use the test methods described onlyby agreement between the parties concerned. These test meth-ods shall not be used for mixtures of different powders, nor forpowders containing binders or lubricants. When the powdercontains agglomerates, the measured surface area
19、 may beaffected by the degree of agglomeration. Methods of de-agglomeration such as that specified in Practice B859 may beused if agreed upon between the parties concerned.4.3 When an “average” particle size of powders is deter-mined by these methods, it should be clearly kept in mind thatthis avera
20、ge size is derived from the determination of thespecific surface area of the powder using a relationship that istrue only for powders of uniform size and spherical shape.Thus, the results of these methods are only estimates ofaverage particle size.4.4 Reported particle size measurement is a function
21、 of boththe actual dimension and shape factor as well as the particularphysical or chemical properties of the particle being measured.Caution is required when comparing data from instrumentsoperating on different physical or chemical parameters or withdifferent particle size measurement ranges. Samp
22、le acquisition,handling, and preparation can also affect reported particle sizeresults.5. Apparatus5.1 MIC Sub-Sieve AutoSizer (MIC SAS),4consisting of anair pump, a calibrated gas mass flow controller, a precision-bore sample tube, a sample tube retaining collar, a spacer tool,a gas flow metering v
23、alve, two precision pressure transducers(inlet and outlet), a stepper motor controlled ballscrew-mounted piston, and computer hardware and software forinstrument control and calculation and reporting of results.Included is accessory equipment consisting of a plug manipu-lator (extraction rod), two p
24、orous plugs, and a supply of paperdisks.NOTE 1When homing the piston, adjust the sample packing assembly(1) as described in the manufacturers directions, with the plugs and paperdisks stacked together and placed on the fixed anvil spigot, or (2) using aspecially designed baseline (homing) gauge inst
25、ead of the plugs and paperdisks. This baseline gauge shall have a height of 20.30 6 0.10 mm. Checkall plug heights when new plugs are purchased and periodically thereafterto make sure all are equal in height.5.2 Powder funnel, stainless steel, with spout outside diam-eter slightly smaller than the s
26、ample tube inside diameter.5.3 The manufacturer provides instructions which should befollowed. Particular attention should be given to proper main-tenance of the instrument with special reference to the instruc-tions on (1) “homing” the piston when turning on from anunpowered state, (2) setting the
27、pressure and periodic checkingof the pressure, (3) condition of O-rings on the piston andsample spigot, and (4) the sample packing assembly (plugs andpaper disks).5.4 Balance, having a capacity of at least 50 g and asensitivity of 0.001 g.6. Standardization of Apparatus6.1 Before proceeding with sta
28、ndardization of the MIC SASinstrument, the following items shall be checked:6.1.1 The sample tube and plugs shall not be worn to thepoint where results are affected.6.1.2 Inspect the O-ring seals for tears and abrasion marks.The O-ring seals shall not be worn to the point where thesample tube moves
29、easily by hand or the pressure readingvaries as the sample tube is moved.6.1.3 The drying agent shall be in proper condition.6.2 Whenever the instrument is turned on from an unpow-ered state, the piston shall be “homed” according to themanufacturers instructions. See Note 1 above.6.3 Before running
30、the initial sample, the pressure shall beset to 50.0 (+0.1, 0.5) cm H2O, using the metering valve; thenchecked and reset if necessary every few hours, or if theambient temperature changes more than 62C.NOTE 2The metering valve position should not be adjusted for repeatruns of the same sample as this
31、 will likely lead to a loss of precision evenif the inlet pressure reading has drifted a little outside the 50.0 (+0.1, 0.5)cm H2O range. Further adjustment is not necessary as the pressure iscontrolled precisely during the particle size measurement.6.4 Standardization is recommended before and afte
32、r anyseries of determinations or at least every 4 hours of continuedoperation. Warm-up of the instrument is required if it has beenoff for more than 30 minutes.6.5 Calibration of the pressure transducers is recommendedevery 36 months, using a traceable external pressure gaugeper the manufacturers in
33、structions.7. Procedure7.1 Temperature of TestMake average particle size deter-minations within 62C of the temperature at which standard-ization of the MIC Sub-Sieve AutoSizer was made. Reset thepressure if the temperature of the test varies more than 62C.7.2 Size of Test SampleThe mass of sample us
34、ed for testsshall be equal in grams (within 65 %) to the true (pore-free)density (in g/cm3) of the powder (for example, iron, 7.8 g;tungsten, 19.3 g; molybdenum, 10.2 g; tantalum, 16.6 g; nickel,8.9 g; and so forth).4The sole source of supply of the MIC Sub-Sieve AutoSizer (MIC SAS) knownto the comm
35、ittee is Micromeritics Instrument Corporation, Particulate Systems,4356 Communications Drive, Norcross, GA 30093-2901, USA. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of th
36、eresponsible technical committee,1which you may attend.E2980 1527.3 Average Particle Size DeterminationThe average par-ticle size determination shall be made by the same operatorwho makes the standardizations and is started after standard-ization or the determination of another sample. Proceed ac-co
37、rding to the MIC SAS manufacturers instructions as fol-lows:7.3.1 Test Method 1 Inorganic Materials (For Example:Metals, Ceramics, Metal Oxides, Metal Carbides):7.3.1.1 Press the “Inorganics” button.7.3.1.2 Determine the mass of the sample to the nearest 0.01g.7.3.1.3 Select the test parameters: 3 c
38、ompressions; slowdecompression; slow termination.7.3.1.4 Proceed to 7.3.3.7.3.2 Test Method2Organic Materials (For Example:Lactose):7.3.2.1 Press the “Organics” button.7.3.2.2 Determine the mass of the sample to the nearest 0.01g.7.3.2.3 Select the test parametersStarting Porosity, StepSize, Final P
39、orositypreviously determined for the particularmaterial being tested.7.3.2.4 Proceed to 7.3.3.7.3.3 Press the “Run Test” button and enter the SampleDetails, including the true density of the material and the actualmass of the sample used.7.3.4 Lay a paper disk over one end of the sample tube usingon
40、e of the porous plugs with the perforated surface of the plugagainst the surface of the paper disk. This crimps the paperaround the edges and the paper precedes the plug into thesample tube. Push the plug into the tube until it is even with theend of the sample tube. Place the sample tube in a verti
41、calposition in a support with the paper side of the plug up.7.3.5 With the aid of the powder funnel, completely transferthe sample into the sample tube by tapping the side of the tubeand funnel. Lay a second paper disk over the top of the sampletube. Place the perforated surface of a porous brass pl
42、ug on topof the paper disk and force the plug and paper disk down intothe sample tube until the plug is just inside the sample tube.7.3.6 Push the sample tube retaining collar onto the sampletube.7.3.7 Push the sample tube onto the fixed anvil spigot withthe retaining collar below the sample tube ho
43、lder, centered inthe sample tube holder and leaving enough of a gap at thebottom of the sample tube to fit the SAS spacer tool below thesample tube.NOTE 3The sample tube may eventually wear and cause faulty values.When this condition is suspected, replace the tube. Sample tubes withobvious wear or s
44、cratches, or both, should be discarded.7.3.8 Insert the SAS spacer tool into the gap below thesample tube.7.3.9 Using an Allen key or cam lock device, lock thesample tube retaining collar into position just below the sampletube holder arms.7.3.10 Press the “Next” button and the test will automati-ca
45、lly run.7.3.11 Monitor the test and remove the spacer after the firstcompression (Test Method 1, Inorganic Materials) or after thepiston has engaged (Test Method 2, Organic Materials).(WarningThe piston moves slowly but with considerableforce. Keep all body parts clear of the mechanism while inmotio
46、n. Do not operate with any guards removed.)NOTE 4The sample tube must be held off the spigot to ensure that thefull force is applied to the sample and not dissipated through the spigot.7.3.12 When the test is finished, the results will be displayedon the instruments screen. Record the Porosity, (Ave
47、rage)Particle Size, and Specific Surface Area (SSA). The data willautomatically be saved with the file name indicated duringentry of the sample details.NOTE 5A calculation of an equivalent spherical diameter (“averageparticle diameter,” “average particle size”), based on the relationshipbetween enve
48、lope-specific surface area and particle diameter, is automati-cally performed by the MIC Sub-Sieve AutoSizer from the values relatedto the porosity and to the permeability of the powder bed measured by theinstrument. In other words, what is determined with the instrument is thespecific surface area
49、of the powder. When an equivalent spherical diameteris determined using the MIC Sub-Sieve AutoSizer, it should be clearlykept in mind that this equivalent spherical diameter is derived from thedetermination of the specific surface area of the powder using a relation-ship that is true only for powders of uniform size and spherical shape.Hence, the term “average particle size,” as defined in 3.2.2, is preferred todescribe the result from this instrument, rather than “particle size” or“equivalent spherical diameter.”7.3.13 For later data extraction
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