1、Designation: B 962 08Standard Test Methods forDensity of Compacted or Sintered Powder Metallurgy (PM)Products Using Archimedes Principle1This standard is issued under the fixed designation B 962; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、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 standard describes a method for measuring thedensity of powder metallurgy products that
3、usually havesurface-connected porosity.1.2 The density of impermeable PM materials, those mate-rials that do not gain mass when immersed in water, may bedetermined using Test Method B311.1.3 The current method is applicable to green compacts,sintered parts, and green and sintered test specimens.1.4
4、With the exception of density values, for which theg/cm3unit is the industry standard, the values stated in SI unitsare to be regarded as the standard. The values given inparentheses are converted in accordance with IEEE/ASTMSI 10 and are for information only.1.5 This standard does not purport to ad
5、dress 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:2B 243 Termin
6、ology of Powder MetallurgyB311 Test Method for Density Determination for PowderMetallurgy (P/M) Materials Containing Less Than TwoPercent Porosity2.2 IEEE/ASTM Standard:SI 10 American National Standard for Use of the Interna-tional System of Units (SI): The Modern Metric System3. Terminology3.1 Defi
7、nitions of powder metallurgy (PM) terms can befound in Terminology B 243. Additional descriptive material isavailable in the Related Material section of Vol. 02.05 of theAnnual Book of ASTM Standards.3.2 Definitions of Terms Specific to This Standard:3.2.1 green density (Dg)the mass per unit volume
8、of anunsintered PM part or test specimen.3.2.2 impregnated density (Di)the mass per unit volumeof a sintered PM part or test specimen, impregnated with oil.3.2.3 sintered density (Ds)the mass per unit volume of asintered, non oil-impregnated PM part or test specimen.4. Summary of Test Method4.1 The
9、test specimen is first weighed in air. It is then oilimpregnated or some other treatment is used to seal thesurface-connected porosity and the specimen is reweighed. Thetest specimen is then weighed when immersed in water and itsdensity calculated based on Archimedes principle.5. Significance and Us
10、e5.1 The volume of a complex shaped PM part cannot bemeasured accurately using micrometers or calipers. Sincedensity is mass per unit volume, a precise method for measur-ing the volume is needed. Archimedes principle may be usedto calculate the volume of water displaced by an immersedobject. For thi
11、s to be applicable to PM materials that containsurface connected porosity, the surface pores are sealed by oilimpregnation or some other means.5.2 The green density of compacted parts or test pieces isnormally determined to assist during press set-up, or for qualitycontrol purposes. It is also used
12、for determining the compress-ibility of base powders, mixed powders, and premixes.5.3 The sintered density of sintered PM parts and sinteredPM test specimens is used as a quality control measure.5.4 The impregnated density of sintered bearings is nor-mally measured for quality control purposes as be
13、arings aregenerally supplied and used oil-impregnated.6. Interferences6.1 A gain in mass when a test specimen is immersed inwater is an indication that the specimen contains surface-connected porosity. Unsealed surface porosity will absorbwater and cause the calculated density values to be higher th
14、anthe true value.1These test methods are under the jurisdiction of ASTM Committee B09 onMetal Powders and Metal Powder Products and are the direct responsibility ofSubcommittee B09.04 on Bearings.Current edition approved Nov. 1, 2008. Published January 2009.2For referenced ASTM standards, visit the
15、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, Un
16、ited States.6.2 Test specimens that contain surface-connected porosityshall be oil impregnated or have the surface-connected porositysealed by some other means prior to their immersion in water.7. Apparatus7.1 Analytical BalancePrecision single-pan balance thatwill permit readings within 0.01 % of t
17、he test specimen mass.See Table 1.7.2 Water ContainerA glass beaker or other suitabletransparent container should be used to contain the water.NOTE 1A transparent container makes it easier to see air bubblesadhering to the test specimen and specimen support when immersed inwater.NOTE 2For the most p
18、recise density determination, the water con-tainer should be of a size that the level of the water does not rise more than2.5 mm (0.10 in.) when the test specimen is lowered into the water.7.3 WaterDistilled or deionized water to which 0.05 to 0.1volume percent of a wetting agent has been added to r
19、educe theeffects of surface tension.NOTE 3Degassing the water by evacuation, boiling, or ultrasonicagitation helps to prevent air bubbles from collecting on the test specimenand support when immersed in water.7.4 Test Specimen Support for Weighing in WaterTwotypical arrangements are shown in Fig. 1.
20、 The suspension wiremay be twisted around the test specimen or the test specimenmay be supported in a wire basket that is attached to thesuspension wire. For either arrangement, a single corrosion-resistant wirefor example, austenitic stainless steel, copper,or nichromeshall be used for the basket a
21、nd suspension wire.The maximum recommended diameter of suspension wire tobe used for various mass ranges is summarized in Table 2.NOTE 4For the most precise density determinations, it is importantthat the mass and volume of all supporting wires immersed in water beminimized.7.5 Oil for Oil-Impregnat
22、ionOil with a viscosity of20 3 10-6to 65 3 10-6m2/s (20 to 65 cSt or 100 to 300 SSU)at 38 C (100 F) has been found to be suitable.7.5.1 In the case of oil-impregnated bearings, make an effortto match the oil that was originally used to impregnate them.7.6 Vacuum Impregnation ApparatusEquipment to im
23、-pregnate the part or test specimen with oil.7.7 ThermometerA thermometer with an accuracy of0.5 C (1.0 F) to measure the temperature of the water.8. Preparation of Test Specimens8.1 The mass of the test specimen shall be a minimum of1.0 g. For small parts, several parts may be combined to reachthe
24、minimum mass.8.2 Thoroughly clean all surfaces of the test specimen toremove any adhering foreign materials such as dirt or oxidescale. Take care with cut specimens to avoid rough surfaces towhich an air bubble may adhere.A100-grit sanding or abrasivegrinding is recommended to remove all rough surfa
25、ces.9. Procedure9.1 The part or test specimen, the analytical balance andsurrounding air shall be at a uniform temperature whenweighing is performed.9.2 For the most precise density determinations, duplicateweighings should be made for all mass measurements. Adjustthe analytical balance to zero prio
26、r to each weighing. Averagethe mass determinations before calculating the density.9.3 For improved repeatability and reproducibility, verifythe analytical balance periodically with a standard mass that isapproximately equal to the part or test specimen mass.9.4 This standard contains three separate
27、test methods;determination of green density, determination of sintereddensity, and determination of impregnated density. Each isdetailed in the following sections.Determination of Green Density9.5 This procedure is used to determine the green density ofPM parts and test specimens.9.5.1 Determine the
28、 mass of the green part or test specimen.This is mass A. This and all subsequent weighings shall be tothe precision stated in Table 1.9.5.2 Oil impregnate the green part or test specimen asfollows:Preferred Procedure9.5.3 Immerse the part or test specimen in oil at roomtemperature.9.5.4 Reduce the p
29、ressure over the sample to 7 kPa (1 psi)or less for 30 minutes, then increase the pressure back toatmospheric pressure and keep the sample immersed for atleast 30 minutes.9.5.5 Remove excess oil by wiping gently with an absor-bent, lint-free material. Take care not to extract oil absorbedwithin the
30、part or test specimen.9.5.6 Do not place or store parts on porous surfaces such aspaper, cloth, or cardboard as these will absorb oil.9.5.7 Proceed to 9.5.13.Alternative Procedure9.5.8 Immerse the part or test specimen in oil at a tempera-ture of 82 6 5 C (180 6 10 F) for at least 4 hours.9.5.9 Cool
31、 by immersing in a bath of the same oil held atroom temperature and keep in this oil for at least 30 minutes.9.5.10 Remove excess oil by wiping gently with an absor-bent, lint-free material. Take care not to extract oil absorbedwithin the part or test specimen.9.5.11 Do not place or store parts on p
32、orous surfaces such aspaper, cloth, or cardboard as these will absorb oil.9.5.12 Proceed to 9.5.13.NOTE 5It may not be necessary to oil impregnate the green part withoil. There may be enough admixed lubricant present in the surface-connected pores to prevent the absorption of water. If the test spec
33、imengains mass when immersed in water it is an indication that the specimenTABLE 1 Balance SensitivityMass,gBalance Sensitivity,gless than 10 0.000110 to less than 100 0.001100 to less than 1000 0.011000 to less than 10 000 0.1B962082contains surface-connected porosity and that it needs to be sealed
34、 by oilimpregnation or some other means.9.5.13 Determine the mass of the oil-impregnated green partor test specimen to the precision stated in Table 1. This is massB.9.5.14 Support the container of water over the pan of thebalance using a suitable bridge as shown in Fig. 2a. Take careto ensure that
35、the bridge does not restrict the free movement ofthe balance pan. The container of water may also be supportedbelow the balance for weighing larger specimens if the balancehas a lower beam hook for this purpose. See Fig. 2b. If thisarrangement is used, it is important to shield the weighingsystem, i
36、ncluding the wire, from the effect of air drafts.9.5.15 Suspend the test specimen support along with thepart or test specimen from the beam hook of the balance. Thewater should cover any wire twists and the specimen supportbasket by at least 6 mm (14 in.) to minimize the effect ofsurface tension for
37、ces on the weighing.9.5.16 The test specimen support and test specimen shallhang freely from the balance beam hook, be free of air bubbleswhen immersed in the water, and be at the same temperature asthe water and the balance.9.5.17 The surface of the water shall be free of dustparticles.9.5.18 Weigh
38、 the part/test specimen and specimen supportimmersed in water. This is mass C.9.5.19 Remove the part/test specimen from the support.9.5.20 Weigh the test specimen support immersed in waterat the same depth as before. This is mass E. The suspensionsupport shall be free of air bubbles and the suspensi
39、on wireshall not be immersed below its normal hanging depth, as achange in depth will change the measured mass.NOTE 6Some balances are capable of being tared. This automaticallyremoves the necessity of reweighing the specimen support every time. Inthis case, tare the specimen support alone, immersed
40、 in water to the samedepth as with the specimen, before weighing the specimen support andpart/test specimen immersed in water. The mass of the specimen supportand specimen immersed in water is mass F, which replaces mass C minusmass E.9.5.21 Measure the temperature of the water to the nearest1 C (2
41、F) and record its density rw, at that temperature, fromTable 3.9.5.22 Calculate the green density of a part or test piecefrom the following formula:FIG. 1 Methods for Holding the Test Specimen When Weighing in WaterTABLE 2 Maximum Recommended Wire DiametersMass,gWire Diameter,mm (in.)less than 50 0.
42、12 (0.005)50 to less than 200 0.25 (0.010)200 to less than 600 0.40 (0.015)600 and greater 0.50 (0.020)B962083Green Density, Dg5ArwB C E!(1)orGreen Density, Dg5ArwB F(2)where:A = the mass of the green part or test piece in air, g,B = the mass of the oil-impregnated green part or testpiece, g,C = the
43、 mass of the oil-impregnated part/test specimenand specimen support immersed in water, g,E = the mass of the oil-impregnated part/test specimensupport immersed in water, g,F = the mass of the oil-impregnated part/test specimen inwater with the mass of the specimen support tared, g,andrw= the density
44、 of the water, g/cm3.If the green part did not need to be oil impregnated then usethe following formula:Green Density, Dg5ArwC E(3)Determination of Sintered Density9.6 This procedure is used to determine the sintered densityof PM parts and test pieces.9.6.1 Determine the mass of the sintered part or
45、 testspecimen to the precision stated in Table 1. This is mass A.This and all subsequent weighings shall be to the precisionstated in Table 1.FIG. 2 Methods for Weighing in WaterTABLE 3 Effect of Temperature on the Density of Air-Free WaterATemperature DensityC (F) g/cm315 (59.0) 0.999116 (60.8) 0.9
46、98917 (62.6) 0.998818 (64.4) 0.998619 (66.2) 0.998420 (68.0) 0.998221 (69.8) 0.998022 (71.6) 0.997823 (73.4) 0.997524 (75.2) 0.997325 (77.0) 0.997026 (78.8) 0.996827 (80.6) 0.996528 (82.4) 0.996229 (84.2) 0.995930 (86.0) 0.9956AMetrological Handbook 145, “Quality Assurance for Measurements,” Nationa
47、lInstitute of Standards and Technology, 1990, pp. 9-10.B9620849.6.2 In order to seal the surface-connected porosity theparts/test pieces are oil impregnated or the pores are filled witha suitable material. If using oil impregnation, oil impregnatethe part or test specimen using one of the procedures
48、 describedin sections 9.5.2-9.5.12.9.6.3 Determine the mass of the oil-impregnated part or testspecimen to the precision stated in Table 1. This is mass B.9.6.4 Support the container of water over the pan of thebalance using a suitable bridge as shown in Fig. 2a. Take careto ensure that the bridge d
49、oes not restrict the free movement ofthe balance pan. The container of water may also be supportedbelow the balance for weighing larger specimens if the balancehas a lower beam hook for this purpose. See Fig. 2b. If thisarrangement is used, it is important to shield the weighingsystem, including the wire, from the effect of air drafts.9.6.5 Suspend the test specimen support along with the partor test specimen from the beam hook of the balance. The watershould cover any wire twists and the specimen support basketby at least 6 mm (14 in.) to mi
