1、Designation: C729 11 (Reapproved 2016)Standard Test Method forDensity of Glass by the Sink-Float Comparator1This standard is issued under the fixed designation C729; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、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 test method covers the determination of the densityof glass or nonporous solids of density from 1.1 to 3.3 g/cm3.It ca
3、n be used to determine the apparent density of ceramics orsolids, preferably of known porosity.1.2 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 pr
4、actices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1217 Test Method for Density and Relative Density (Spe-cific Gravity) of Liquids by Bingham PycnometerE77 Test Method for Inspection and Verification of Ther-mometersF77 Test M
5、ethod for Apparent Density of Ceramics forElectron Device and Semiconductor Application (With-drawn 2001)33. Summary of Method3.1 The specimen of unknown density is compared with areference standard of known density. The specimen to bemeasured is placed in a test tube containing a solution whosedens
6、ity at 35C is within 0.0200 g/cm3of the density of thespecimen at 25C. The solution is prepared using miscibleliquids of known densities bracketing the desired range. Thetube also contains a glass density reference standard whosedensity at 35C is close to that of the solution at 35C; the tubeis imme
7、rsed in a variable-temperature comparator bath. Ini-tially the solutions, specimen, and standard are at a temperaturenear 25C, and both the standard and the specimen float in thesolution. The temperature of the system is raised at a uniformrate. Because the volumetric expansion coefficient of thesol
8、ution is much higher than those of the glass pieces, itsdensity decreases more rapidly and eventually both the stan-dard and the specimen will sink (settle) in the solution. Thetemperatures at which the specimen and standard reach themid-point of the test tube are noted and by use of special tables,
9、the density of the specimen is obtained.3.2 Range of a Given Density SolutionA given densitysolution can be used to measure specimens whose density iswithin 60.0200 g/cm3of the density of the solution at 35C, byoperating the comparator bath in the range 25 to 45C.4. Significance and Use4.1 The sink-
10、float comparator method of test for glassdensity provides the most accurate (yet convenient for practicalapplications) method of evaluating the density of small piecesor specimens of glass. The data obtained are useful for dailyquality control of production, acceptance or rejection underspecificatio
11、ns, and for special purposes in research and devel-opment.4.2 Although this test scope is limited to a density rangefrom 1.1 to 3.3 g/cm3, it may be extended (in principle) tohigher densities by the use of other miscible liquids (TestMethod F77) such as water and thallium malonate-formate(approximat
12、ely 5.0 g/cm3). The stability of the liquid and theprecision of the test may be reduced somewhat, however, athigher densities.5. Apparatus5.1 Single Tube and Multiple-Tube Comparators (TestMethod E77)A single-tube comparator can be constructedfrom materials readily available in a typical laboratory,
13、 anduseful if one wishes to measure the density of materials withina fairly narrow range, or if only a few tests need to be run eachday. The multiple-tube comparator can be purchased commer-cially. It is useful if materials with a wide range of density mustbe tested or if many specimens must be test
14、ed each day. Thecomparators shall consist of the following:5.1.1 Single-Tube Comparator (Fig. 1):5.1.1.1 Circulating Water Bath, consisting of a 4000-cm3beaker, a cover plate supporting test tubes and thermometer, a1This test method is under the jurisdiction of ASTM Committee C14 on Glassand Glass P
15、roducts and is the direct responsibility of Subcommittee C14.04 onPhysical and Mechanical Properties.Current edition approved Oct. 1, 2016. Published October 2016. Originallyapproved in 1972. Last previous edition approved in 2011 as C729 11. DOI:10.1520/C0729-11R16.2For referenced ASTM standards, v
16、isit 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright
17、ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1cooling water coil made from copper tubing, an electricallydriven stirrer, and containing an immersion heater with rheostatfor controlling heating rate, or heated by an external heatsource such as
18、 a hot plate.5.1.1.2 Test Tubes, two, 100-cm3capacity. The cover platesupports the test tubes, which extended into the water bath.One tube contains the density solution, the test specimen, thestandard, and a glass or TFE-fluorocarbon cage (Fig. 2) thatkeeps the specimens immersed in the solution. Th
19、e second testtube contains density solution and a thermometer; both testtubes employ rubber stoppers for supporting the cage orthermometer.5.1.1.3 Thermometers, two, mercury, readable to 0.1Cbetween 20 and 50C. One thermometer passes through arubber stopper supported by the cover plate into the wate
20、r bath.The second thermometer passes through a rubber stopper intothe test tube that contains density solution only. Thermistors,resistive thermal devices (RTD), or thermocouples capable ofMetric Equivalentsin.1412 1134 29mm 6.4 12.7 25.4 44.4 51 229FIG. 1 Single Tube Sink-Float Density ApparatusC72
21、9 11 (2016)2measuring and displaying at least 0.1C accuracy between 20and 50C can be used in lieu of mercury thermometers.5.1.2 Multiple-Tube ComparatorThe commercially ob-tainable multiple-tube comparator employs the same principleas the single-tube comparator, except that the multiple-tubetype con
22、tains additional specimen tubes. These specimen tubesmay contain similar density solutions if a large number ofspecimens with similar density are to be measured; they maycontain density solutions of differing density if a number ofspecimens with a range of densities are to be measured.6. Reagents an
23、d Materials6.1 Density Reference StandardsThe reference standardshall be a solid piece of glass with a volume between 0.10 and0.15 cm3, and a ratio of major to minor dimensions notexceeding 2.0. It shall have a smooth surface and be free ofseeds, cords, and cracks. A quantity of such standards may b
24、ecut from a 20-g piece of glass similarly free of defects, withdensity at 25C (25) known to 60.0001 g/cm3. The density ofsuch a standard glass can be determined to 60.00001 g/cm3bya precise buoyancy method.4Determine the settling tempera-ture of each reference standard to the nearest 0.1C and discar
25、dany that deviate more than 0.1C from mean temperature. Lessprecise density standards are commercially available.6.2 Density SolutionThe following organic liquids5aremixed to provide a solution of the desired density:6.2.1 Isopropyl Salicylate, density (25C) approximately1.10 g/cm3or alpha-bromonaph
26、thalene, density (25C) ap-proximately 1.49 g/cm3.6.2.2 sym-Tetrabromoethane, density (25C) approximately2.96 g/cm3.6.2.3 Methylene Iodide, density (25C) approximately 3.32g/cm3.NOTE 1Methylene iodide, sym-tetrabromoethane, and alpha-bromonaphthalene are light-sensitive. These liquids should be store
27、d inlight-protective containers.Apiece of copper wire in the methylene iodidecontainer will help retard decomposition.6.2.4 The density solution consists of mixtures of isopropylsalicylate and sym-tetrabromoethane for densities between 1.10and 2.96 g/cm3, and of sym-tetrabromoethane and methyleneiod
28、ide for densities between 2.96 and 3.32 g/cm3. Properamounts of the two liquids to be used are found by simultane-ous solution of:sVs5 1V112V2(1)Vs5 V11V2(2)s51V112V2!/V11V2! (3)where:s= density of solution density of standard at35C,Vs= volume of solution to be prepared,1and 2= densities of the comp
29、onent liquids at 35C,andV1and V2= volumes of the component liquids at 35C.6.2.5 Solution PreparationApproximate volumes of liq-uids required to supply desired density sare shown in Table1. Mix the two required volumes of liquids 1 and 2 (6.2.4)ina beaker, set on a hot plate, and warm to 35C. Place a
30、 densitystandard in the solution. Adjust the mixture by adding one ormore drops of either component until the density standardsettles at 35 6 0.2C in the well-stirred solution.4Bowman, H.A., and Schoonover, R. M., “Procedure for High Precision DensityDeterminations by Hydrostatic Weighing,” Journal
31、of Research, National Bureau ofStandards, 71 C, 3, 1967, p. 179.5These liquids are available from most chemical supply companies.FIG. 2 TFE-Flourocarbon Cage for 100-mL Test TubeTABLE 1 Volumes of Liquids for Solutions of Various Densitiessg/cm3at 35CVolume of Material Used, cm3IsopropylSalicylatesy
32、m-Tetra-bromo-ethaneMethyleneIodide2.103 135 165 .2.136 127 173 .2.190 120 180 .2.222 115 185 .2.236 113 187 .2.257 109 191 .2.291 104 196 .2.315 100 200 .2.335 95 205 .2.363 92 208 .2.403 85 215 .2.434 80 220 .2.448 78 222 .2.473 74 226 .2.495 70 230 .2.511 68 232 .2.529 65 235 .2.560 60 240 .2.589
33、 56 244 .2.596 54 246 .2.619 50 250 .2.633 48 252 .2.669 42 258 .2.702 37 263 .2.728 33 267 .2.757 28 272 .2.812 19 281 .2.847 13 287 .2.863 10 290 .2.893 6 294 .2.933 . 300 12.960 . 277 232.999 . 248 523.035 . 214 863.054 . 198 1023.096 . 168 132C729 11 (2016)37. Preparation of Density-Temperature
34、Tables7.1 Tables are prepared from the equations of this section torelate the specimen density at 25C to its settling temperature.These tables are prepared once for each glass referencestandard-density solution system. Subsequent supplies of den-sity solutions prepared for use with the same glass re
35、ferencestandard will be sufficiently similar in expansion and densitycharacteristics so that the same table can be used.7.2 Determination of Temperature Coeffcient of DensityMeasure the density of the solution at approximately 25 and45C using the Bingham pycnometer, Test Method D1217,orequivalent py
36、cnometer method. Calculate the temperaturecoefficient of density, C, as follows:C5T12 T2!/T12 T2! (4)where:C= temperature coefficient of the solution,g/cm3C, andT1and T2= density of the solution at temperature T1andT2, g/cm3.7.3 Equations for Determination of Density:NOTE 2Alternative equations or m
37、ethod of calculation may be used inconjunction with different density tables and standard settling tempera-tures.7.3.1 These equations relate the specimen density to itssettling temperatures. Express the exact relationship:T5 s1CT 2 Ts! (5)where:T= density of specimen at its settling temperature, T,
38、 ands= density of standard at its settling temperature, Ts,approximately 35C.7.3.2 If the thermal expansions of a specimen and standardare similar, express their densities at 25C as follows:255 s251C13ss!T 2 Ts!(6)where:25= specimen density at 25C,s 25= standard density at 25C, ands= linear expansio
39、n of standard expansion ofspecimen.7.3.3 It is convenient to fix 35C as the settling temperatureof the standard, as it will vary slightly with heating rate,operator, and liquid density. The specimen settling temperaturemust be corrected as follows:Tc5 T135 2 Ts!(7)where:Tc= corrected specimen settli
40、ng temperature,T = observed specimen settling temperature, andTs= observed standard settling temperature.Eq 6 then becomes:255 s251C13ss!Tc2 35! (8)7.4 Density TableThis table is prepared and used whenmany routine densities are to be determined. Eq 8 is solved forTcbetween 25 and 45C in 0.1C increme
41、nts, and specimendensity at 25C is tabulated with corrected specimen settlingtemperature Tc. A typical density table is shown in Table 2.7.5 Density Equation for Unlike ExpansionsIf the thermalexpansions of specimen and standard differ, specimen densitywill be in error by approximately 0.0001 g/cm3f
42、or every20107/C mismatch in expansion. This error is greater if thespecimen settles above 35C and less if it settles below 35C.Use the following equation, which is accurate to 60.0001g/cm3:255 s251.0000 2 30 s!13Tc2 25!#1CTc2 35!(9)where: = linear expansion coefficient of specimen.8. Procedure for D
43、etermining Density of Test Specimens8.1 Prepare the specimen for testing by cutting from thesample a piece comparable in size with the standard. The testspecimen should be smooth and free of bubbles and cracks.Identify the specimen using a diamond-point marking pencil orby cutting it to a distinctiv
44、e shape. Clean the specimen inreagent grade alcohol or acetone and wipe dry with silicone-free lens tissue. Place specimen in the solution (Note 3) thatcontains the standard. The bath and solution temperaturesshould be approximately 25 6 3C, and both specimen andstandard should float.NOTE 3Adsorbed
45、moisture on the specimen surface will lower themeasured density. Moisture, from condensation, on the solution surfaceshould be removed by periodically filtering the solution through coarsefilter paper.8.2 Place all the tubes, thermometers, stoppers, etc., in theirproper location in the bath, and rap
46、idly heat the bath (1 to2C/min), noting the temperature of the density solution atwhich the test specimen (or the standard) begins to settle.8.3 Adjust the bath temperature by cooling to 2 to 4Cbelow the expected settling temperature of the specimen (orstandard). Allow the bath and solutions to come
47、 to equilibriumfor 10 min, then heat the bath at a rate of 0.1 6 0.02C/min.Heating rates can be controlled by adjusting the power to thehotplate or immersion heater and the cooling water flow rate.Cooling water is used as a fine adjustment of heating rate.8.4 As either the specimen or standard begin
48、 to settle in thesolutions, note the temperature at which either is halfwaybetween upper and lower cage disks. The bath and densitysolution temperatures must agree within 0.4C when thetemperature is recorded, with the bath temperature beinghigher. Record T and Ts.8.5 Calculate the corrected specimen
49、 settling temperature,Tc,byEq 7. From an appropriate density table prepared fromEq 4 and 8, read the density that corresponds to the correctedspecimen settling temperature, Tc. This density is the density ofthe specimen at 25C, 25.8.6 Up to three test specimens can be run in a single tubesimultaneously.C729 11 (2016)49. Report9.1 Report the following:9.1.1 Identification of test sample, product, manufacturer,code number, date, etc. as required,9.1.2 Test
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