1、Designation: B962 15B962 17Standard 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.1.6 This international standard was developed in accordance with internationally recognized principles on standardiza
7、tionestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2B243 Terminology of Powder MetallurgyB311 Test Method
8、for Density of Powder 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 AST
9、M Standards.3.2 Definitions 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
10、 mass per unit volume 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
11、is then weighed when 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
12、 April 1, 2015April 1, 2017. Published April 2015May 2017. Originally approved in 2008. Last previous edition approved in 20142015 as B962 14.15. DOI: 10.1520/B0962-15.10.1520/B0962-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm
13、.org. For Annual 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. Because
14、it may not be technically 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
15、at the end of this 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 vo
16、lume, a precise 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 othe
17、r means.5.2 The 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 sin
18、tered PM test specimens 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 a
19、n indication that 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 po
20、rositysealed by 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 c
21、ontain the water.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.
22、10in. (2.5 mm) 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 preve
23、nt air bubbles 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
24、 attached to the 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 i
25、n Table 2.NOTE 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 b
26、e suitable.7.5.1 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 t
27、he 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 reach the minimum mass.8.2 Thoroughly clean all surfaces of the test specimen to remove any adhering foreign materials such as d
28、irt or oxide scale. 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 SensitivityReadabilityMass,gBalance Sensitivity,Readable to,gless than 10 0.000110 to less tha
29、n 100 0.001100 to less than 1000 0.011000 to less than 10 000 0.1B962 1729. 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 ma
30、de for all mass measurements. Adjust theanalytical 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
31、the part or test specimen mass.9.4 This 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 de
32、termine the green density of PM parts 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
33、Immerse the part or test specimen in oil 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 grea
34、ter 0.020 (0.50)B962 1739.5.4 Reduce the 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
35、care not to extract oil absorbed within 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
36、 (82 6 5 C) for at least 4 hours.9.5.9 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 speci
37、men.9.5.11 Do not place or store parts 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 preve
38、nt the absorption of water. If the test 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 speci
39、men to the precision stated in Table 1. 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
40、 below thebalance for weighing larger 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 1749.5.15 Suspend
41、the test specimen support along with the 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
42、specimen shall hang freely from the balance 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 wa
43、ter. 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 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 de
44、pth, as a change in depthwill change the 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, befor
45、e weighing the specimen support and part/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, fr
46、om Table 3.9.5.22 Calculate the green 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 o
47、f the oil-impregnated part/test specimen 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
48、 the water, g/cm3.If the green part did not need to be oil impregnated then use the following formula: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.9.6.1 Determine the mass of the sintered
49、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.TABLE 3 Effect of Temperature on the Density of Air-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 Metrological Handbook 145, “Quality As
