1、Designation: B962 14B962 15Standard Test Methods forDensity of Compacted or Sintered Powder Metallurgy (PM)Products Using Archimedes Principle1This standard is issued under the fixed designation B962; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、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.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.1 T
3、his standard describes a method for measuring the density of powder metallurgy products that usually havesurface-connected porosity.1.2 The density of impermeable PM materials, those materials that do not gain mass when immersed in water, may bedetermined using Test Method B311.1.3 The current metho
4、d is applicable to green compacts, sintered parts, and green and sintered test specimens.1.4 With the exception of the values for density and the mass used to determine density, for which the use of the gram per cubiccentimetre (g/cm3) and gram (g) units is the long-standing industry practice, the v
5、alues in inch-pound units are to be regarded asstandard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and arenot considered standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with it
6、s use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B243 Terminology of Powder MetallurgyB311 Test Method for Density of Powde
7、r Metallurgy (PM) Materials Containing Less Than Two Percent Porosity3. Terminology3.1 Definitions of powder metallurgy (PM) terms can be found in Terminology B243. Additional descriptive material isavailable in the Related Material section of Vol. 02.05 of the Annual Book of ASTM Standards.3.2 Defi
8、nitions of Terms Specific to This Standard:3.2.1 green density (Dg)the mass per unit volume of an unsintered PM part or test specimen.3.2.2 impregnated density (Di)the mass per unit volume of a sintered PM part or test specimen, impregnated with oil.3.2.3 sintered density (Ds)the mass per unit volum
9、e of a sintered, non oil-impregnated PM part or test specimen.4. Summary of Test Method4.1 The test specimen is first weighed in air. It is then oil impregnated or some other treatment is used to seal thesurface-connected porosity and the specimen is reweighed. The test specimen is then weighed when
10、 immersed in water and itsdensity calculated based on Archimedes principle.1 These test methods are under the jurisdiction of ASTM Committee B09 on Metal Powders and Metal Powder Products and are the direct responsibility of SubcommitteeB09.04 on Bearings.Current edition approved Sept. 1, 2014April
11、1, 2015. Published September 2014April 2015. Originally approved in 2008. Last previous edition approved in 20132014 asB962 13.14. DOI: 10.1520/B0962-14.10.1520/B0962-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annua
12、l Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be t
13、echnically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of t
14、his standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 The volume of a complex shaped PM part cannot be measured accurately using micrometers or calipers. Since density ismass per unit volume, a precise
15、 method for measuring the volume is needed. Archimedes principle may be used to calculate thevolume of water displaced by an immersed object. For this to be applicable to PM materials that contain surface connectedporosity, the surface pores are sealed by oil impregnation or some other means.5.2 The
16、 green density of compacted parts or test pieces is normally determined to assist during press set-up, or for qualitycontrol purposes. It is also used for determining the compressibility of base powders, mixed powders, and premixes.5.3 The sintered density of sintered PM parts and sintered PM test s
17、pecimens is used as a quality control measure.5.4 The impregnated density of sintered bearings is normally measured for quality control purposes as bearings are generallysupplied and used oil-impregnated.6. Interferences6.1 A gain in mass when a test specimen is immersed in water is an indication th
18、at the specimen contains surface-connectedporosity. Unsealed surface porosity will absorb water and cause the calculated density values to be higher than the true value.6.2 Test specimens that contain surface-connected porosity shall be oil impregnated or have the surface-connected porositysealed by
19、 some other means prior to their immersion in water.7. Apparatus7.1 Analytical BalancePrecision single-pan balance that will permit readings within 0.01% of the test specimen mass. SeeTable 1.7.2 Water ContainerA glass beaker or other suitable transparent container should be used to contain the wate
20、r.NOTE 1A transparent container makes it easier to see air bubbles adhering to the test specimen and specimen support when immersed in water.NOTE 2For the most precise density determination, the water container should be of a size that the level of the water does not rise more than 0.10in. (2.5 mm)
21、when the test specimen is lowered into the water.7.3 WaterDistilled or deionized water to which 0.05 to 0.1 volume percent of a wetting agent has been added to reduce theeffects of surface tension.NOTE 3Degassing the water by evacuation, boiling, or ultrasonic agitation helps to prevent air bubbles
22、from collecting on the test specimen andsupport when immersed in water.7.4 Test Specimen Support for Weighing in WaterTwo typical arrangements are shown in Fig. 1. The suspension wire may betwisted around the test specimen or the test specimen may be supported in a wire basket that is attached to th
23、e suspension wire.For either arrangement, a single corrosion-resistant wirefor example, austenitic stainless steel, copper, or nichromeshall beused for the basket and suspension wire. The maximum recommended diameter of suspension wire to be used for various massranges is summarized in Table 2.NOTE
24、4For the most precise density determinations, it is important that the mass and volume of all supporting wires immersed in water be minimized.7.5 Oil for Oil-ImpregnationOil with a viscosity of 20 to 65 cSt or 100 to 300 SSU (20 10-6 to 65 10-6 m2/s) at100 F (38 C) has been found to be suitable.7.5.
25、1 In the case of oil-impregnated bearings, make an effort to match the oil that was originally used to impregnate them.7.6 Vacuum Impregnation ApparatusEquipment to impregnate the part or test specimen with oil.7.7 ThermometerA thermometer with an accuracy of1.0 F (0.5 C) to measure the temperature
26、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 reach the minimum mass.8.2 Thoroughly clean all surfaces of the test specimen to remove any adhering foreign materials such as dirt or oxide sc
27、ale. Takecare with cut specimens to avoid rough surfaces to which an air bubble may adhere. A 100-grit sanding or abrasive grinding isrecommended to remove all rough surfaces.TABLE 1 Balance SensitivityMass,gBalance Sensitivity,gless than 10 0.000110 to less than 100 0.001100 to less than 1000 0.011
28、000 to less than 10 000 0.1B962 1529. Procedure9.1 The part or test specimen, the analytical balance and surrounding air shall be at a uniform temperature when weighing isperformed.9.2 For the most precise density determinations, duplicate weighings should be made for all mass measurements. Adjust t
29、heanalytical balance to zero prior to each weighing. Average the mass determinations before calculating the density.9.3 For improved repeatability and reproducibility, verify the analytical balance periodically with a standard mass that isapproximately equal to the part or test specimen mass.9.4 Thi
30、s standard contains three separate test methods; determination of green density, determination of sintered density, anddetermination of impregnated density. Each is detailed in the following sections.Determination of Green Density9.5 This procedure is used to determine the green density of PM parts
31、and test specimens.9.5.1 Determine the mass of the green part or test specimen. This is mass A. This and all subsequent weighings shall be to theprecision stated in Table 1.9.5.2 Oil impregnate the green part or test specimen as follows:Preferred Procedure9.5.3 Immerse the part or test specimen in o
32、il at room temperature.FIG. 1 Methods for Holding the Test Specimen When Weighing in WaterTABLE 2 Maximum Recommended Wire DiametersMass,gWire Diameter,in. (mm)less than 50 0.005 (0.12)50 to less than 200 0.010 (0.25)200 to less than 600 0.015 (0.40)600 and greater 0.020 (0.50)B962 1539.5.4 Reduce t
33、he pressure over the sample to 1 psi (7 kPa) or less for 30 minutes, then increase the pressure back to atmosphericpressure and keep the sample immersed for at least 30 minutes.9.5.5 Remove excess oil by wiping gently with an absorbent, lint-free material. Take care not to extract oil absorbed withi
34、n thepart or test specimen.9.5.6 Do not place or store parts on porous surfaces such as paper, 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 temperature of 180 6 10 F (82 6 5 C) for at least 4 hours.9.5.9
35、 Cool by immersing in a bath of the same oil held at room temperature and keep in this oil for at least 30 minutes.9.5.10 Remove excess oil by wiping gently with an absorbent, lint-free material. Take care not to extract oil absorbed withinthe part or test specimen.9.5.11 Do not place or store parts
36、 on porous surfaces such as paper, 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 with oil. There may be enough admixed lubricant present in the surface-connectedpores to prevent the absorption of water. If the tes
37、t specimen gains mass when immersed in water it is an indication that the specimen containssurface-connected porosity and that it needs to be sealed by oil impregnation or some other means.9.5.13 Determine the mass of the oil-impregnated green part or test specimen to the precision stated in Table 1
38、. This is massB.9.5.14 Support the container of water over the pan of the balance using a suitable bridge as shown in Fig. 2a. Take care to ensurethat the bridge does not restrict the free movement of the balance pan. The container of water may also be supported below thebalance for weighing larger
39、specimens if the balance has a lower beam hook for this purpose. See Fig. 2b. If this arrangement isused, it is important to shield the weighing system, including the wire, from the effect of air drafts.FIG. 2 Methods for Weighing in WaterB962 1549.5.15 Suspend the test specimen support along with t
40、he part or test specimen from the beam hook of the balance. The watershould cover any wire twists and the specimen support basket by at least 14 in. (6 mm) to minimize the effect of surface tensionforces on the weighing.9.5.16 The test specimen support and test specimen shall hang freely from the ba
41、lance beam hook, be free of air bubbles whenimmersed in the water, and be at the same temperature as the water and the balance.9.5.17 The surface of the water shall be free of dust particles.9.5.18 Weigh the part/test specimen and specimen support immersed in water. This is mass C.9.5.19 Remove the
42、part/test specimen from the support.9.5.20 Weigh the test specimen support immersed in water at the same depth as before. This is mass E. The suspension supportshall be free of air bubbles and the suspension wire shall not be immersed below its normal hanging depth, as a change in depthwill change t
43、he measured mass.NOTE 6Some balances are capable of being tared. This automatically removes the necessity of reweighing the specimen support every time. In thiscase, tare the specimen support alone, immersed in water to the same depth as with the specimen, before weighing the specimen support and pa
44、rt/testspecimen immersed in water. The mass of the specimen support and specimen immersed in water is mass F, which replaces mass C minus mass E.9.5.21 Measure the temperature of the water to the nearest2 F (1 C) and record its density w, at that temperature, from Table 3.9.5.22 Calculate the green
45、density of a part or test piece from the following formula:Green Density,Dg 5 AwB 2C 2E! (1)orGreen Density,Dg 5 AwB 2F (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 test piece, g,C = the mass of the oil-impregnated part/test specim
46、en and specimen support immersed in water, g,E = the mass of the oil-impregnated part/test specimen support immersed in water, g,F = the mass of the oil-impregnated part/test specimen in water with the mass of the specimen support tared, g, andw = the density of the water, g/cm3.If the green part di
47、d not need to be oil impregnated then use the following formula:Green Density,Dg 5 AwC 2E (3)Green Density,Dg 5 AwA 2 B 2C!# (3)Determination of Sintered Density9.6 This procedure is used to determine the sintered density of PM parts and test pieces.TABLE 3 Effect of Temperature on the Density of Ai
48、r-Free WaterATemperature DensityF (C) g/cm359.0 (15) 0.999160.8 (16) 0.998962.6 (17) 0.998864.4 (18) 0.998666.2 (19) 0.998468.0 (20) 0.998269.8 (21) 0.998071.6 (22) 0.997873.4 (23) 0.997575.2 (24) 0.997377.0 (25) 0.997078.8 (26) 0.996880.6 (27) 0.996582.4 (28) 0.996284.2 (29) 0.995986.0 (30) 0.9956A
49、 Metrological Handbook 145, “Quality Assurance for Measurements,” NationalInstitute of Standards and Technology, 1990, pp. 9-10.B962 1559.6.1 Determine the mass of the sintered part or test specimen to the precision stated in Table 1. This is mass A. This and allsubsequent weighings shall be to the precision stated in Table 1.NOTE 7Oil impregnated specimens or specimens that contain any oil are to be free of lubricant for determining mass A. Remove the oil in a Soxhletapparatus using a suitable solvent, such as petroleum ether. A
