1、Designation: C 1351M 96 (Reapproved 2007)METRICStandard Test Method forMeasurement of Viscosity of Glass Between 104Pas and108Pas by Viscous Compression of a Solid Right CylinderMetric1This standard is issued under the fixed designation C 1351M; the number immediately following the designation indic
2、ates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination
3、of the viscos-ity of glass from 104Pas to 108Pas by measuring the rate ofviscous compression of a small, solid cylinder.21.2 The values stated in SI units are to be regarded as thestandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is
4、 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:3C 338 Test Method for Softening Point of GlassC 965 Practice for Measuring Viscosit
5、y of Glass Above theSoftening PointC 1350M Test Method for Measurement of Viscosity ofGlass Between Softening Point and Annealing Range(Approximately 108 Pas to Approximately 1013 Pas) byBeam Bending (Metric)3. Terminology3.1 parallel plate viscometera device used to determinethe viscosity of glass
6、from approximately 104Pas to 108Pasby measuring the rate of change in thickness of a cylindricalspecimen between parallel plates moving perpendicular to theircommon central axis. The equation for calculating viscosity bythe parallel plate method is:h52pMgh530V dh/dt!2ph31 V!1 1aT!(1)where:h = viscos
7、ity, Pas,M = applied load, g,g = acceleration due to gravity, 980 cm/s2,t = time, s,V = specimen volume, cm3,h = specimen thickness at time t, cm,dh/dt = compression rate, cm/s, anda = glass mean coefficient of thermal expansion, 25Cto the measurement temperature, T, m/m/C. SeeNote 1.NOTE 1The term
8、(1 + aT) corrects for the specimen dimensionalchanges due to thermal expansion. For low thermal expansion glasses, itcan be ignored. However, for a glass with an a of 20 3 106/C at ameasurement temperature of 1000C, this term produces a correction of2 %. Only an estimate of a is necessary since the
9、correction is small. Usetwice the room temperature coefficient if data are unavailable.4. Significance and Use4.1 This test method is well suited for measuring theviscosity of glasses between the range within which rotationalviscometry (see Practice C 965) is useful and the range withinwhich beam be
10、nding viscometry is useful (see Test MethodC 1350M). It can be used to determine the viscosity/temperature curve in the region near the softening point (seeTest Method C 338). This test method is useful for providinginformation related to the behavior of glass as it is formed intoan object of commer
11、ce, and in research and development.5. Apparatus5.1 The apparatus shall consist of a furnace, a means ofcontrolling and measuring its temperature and heating rate,specimen holders and loading rod, and a means of measuringthe rate of viscous compression of the glass specimen.1This test method is unde
12、r the jurisdiction of ASTM Committee C14 on Glassand Glass Products and is the direct responsibility of Subcommittee C14.04 onPhysical and Mechanical Properties.Current edition approved April 1, 2007. Published May 2007. Originallyapproved in 1996. Last previous edition approved in 2002 as C 1351M -
13、 96(2002).2Fontana, E. H., “A Versatile Parallel-Plate Viscometer For Glass ViscosityMeasurements to 1000C,” Bulletin of the American Ceramic Society, Vol 49, No.6, 1970, pp. 594597.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.o
14、rg. 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, United States.5.2 Furnace:5.2.1 The furnace shall be electrically heated by re
15、sistanceelements. The dimensions and details of the furnace construc-tion are not critical; its cross-section can be circular of 75 mm(3 in.) diameter or square of sides of 75 mm. The furnaceshould have a constant temperature zone that covers thespecimen geometry, including the compression range. Di
16、ffer-ences in temperature greater than 2C within the constanttemperature zone are unacceptable.5.3 Temperature Measuring and Indicating Instruments:5.3.1 For the measurement of temperature, there shall beprovided a calibrated Type K, R, or S thermocouple. Thethermocouple shall be housed in a double-
17、bore alumina tubewith its junction placed within 5 mm of the specimen near theaxis of the furnace. The thermocouple shall be referenced to0C by means of an ice bath, and its emf measured with acalibrated potentiometer that can be read with a sensitivityequivalent to6 0.1C and an accuracy of 60.5C. P
18、recautionsshall be taken to ensure that the ice bath is maintained at 0Cthroughout the test.Alternately, the output of the thermocouplecan be measured on a calibrated, direct reading meter (elec-tronic thermometer) that can be read with a sensitivity of60.1C and an accuracy of 60.5C. See Note 3 for
19、tempera-ture lag-lead corrections.5.4 Furnace Control:5.4.1 Suitable means shall be provided for maintaining thefurnace at a fixed control point and for controlling the heatingand cooling rates. Commercially available programmingequipment provides excellent control. A variable transformerwith manual
20、 control is an inexpensive, but less adequate meansof accomplishing the required control.5.5 Specimen Holder and Loading Rod:5.5.1 A typical configuration is presented in Fig. 1. Posi-tioned horizontally on top of the support stand is a stationaryplate (see Note 2),6mm(;14 in.) thick by diameter of
21、thesupport stand. A movable plate, 6 mm thick by 44 mmminimum diameter is placed parallel and concentrically abovethe fixed plate. (See parallel plates in Fig. 1.) Attached to thetop center of the movable plate in a shrink fit configuration isa 9-mm (;38-in.) diameter centerless-ground alumina rod o
22、flength sufficient to reach approximately 150 mm (6 in.) beyondthe top of the furnace or its supporting structure, or both. Thisassembly provides a means for loading the specimen duringmeasurement. Bushings attached to the external frame guidethe shaft with a minimum amount of friction.NOTE 2Alumina
23、 and vitreous silica are suitable materials for theassembly components, as are noble or low expansion metals used in pairs.The user must observe temperature limitations for these alternate materi-als.5.6 Extensometer for Measuring Thickness Change:5.6.1 The means of observing the rate of thickness c
24、hangeof the specimen should allow reliable reading of total change ofat least 6 mm. The extensometer shall permit direct reading of0.010 mm and estimates of 0.001 mm. Its accuracy shall besuch that the error of indication will not exceed 62 % for anymeasured translation. This will limit the minimum
25、translationthat may be used in calculation. A linearly variable differentialtransformer (LVDT) is suitable for this purpose, as is any otherdevice (for example, optical or capacitative), provided thatlength changes are reliably measured as specified.5.7 Micrometer Calipers:5.7.1 Micrometer calipers,
26、 which can be read to an accuracyof at least 0.01 mm are required for measuring specimendimensions.6. Preparation of Test Specimen6.1 Specimens required for this test method are small, right,circular cylinders. Nominal dimensions are 6 mm (;14 in.) to12 mm (;12 in.) diameter and 3 to 6 mm thick. Spe
27、cimens canbe either core-drilled from flat stock or sliced from a rod. Inboth cases, the flat surfaces must be ground and polished to beplane-parallel to 60.001 mm. Cylinders made by dry pressingof frit at high pressure can provide meaningful data.7. Calibration7.1 Direct calibration of the apparatu
28、s is accomplished byusing standard glasses, such as those supplied and certified bythe National Institute of Standards and Technology (NIST),having known viscosity/temperature values.4Bias should becorrected by overall instrument calibration.4Table 2, Annual Book of ASTM Standards , Vol 15.01, NIST
29、Special PublicationNo. 260.FIG. 1 A Typical Parallel Plate ViscometerC 1351M 96 (2007)27.1.1 Determine the viscosity using test cylinders of cali-brating glasses which cover a range of cross-sections expectedto be used for routine testing. Determine the viscosity byfollowing the standard procedure d
30、escribed in Sections 8 and 7.7.1.2 Mathematically fit resulting data to a convenient form(for example, polynomial or Fulcher5equation). Fit the datasupplied for the glass SRM to a Fulcher equation.7.1.3 Calculate the viscosities from both equations deter-mined in 7.1.2 at 20C minimum intervals over
31、the measuredrange. Determine the viscosity ratio, hSRM fit/hmeasured fit=fractional correction, and construct a calibration curve offractional correction versus log viscosity (measured fit). This isused to correct experimental viscosity data. (See Note 3.)Corrections greater than 20 % are cause for
32、concern and shouldinitiate apparatus troubleshooting.NOTE 3If analyses are performed under some heating or cooling ratetime-temperature function, the thermocouple temperature may lag or leadthe actual sample temperature. If thermocouple lag or lead does occur, thecalibration curve described in 7.1.3
33、 would incorporate this temperaturebias as well as any viscosity bias. To assess whether thermocouple lag orlead exists, viscosities for a glass SRM may be measured under isothermalconditions at several temperatures. Compare temperatures at equivalentviscosity levels from the analysis of the same gl
34、ass SRM measured underthe heating or cooling rate condition. Temperature differences indicatethermocouple lag or lead. The difference should be applied as a tempera-ture correction to measured temperatures prior to generating the calibra-tion curve (7.1.3) or applying the calibration correction to t
35、est data(Section 9).8. Procedure8.1 Deflection data may be taken either under isothermalconditions or heating at a controlled rate not to exceed5C/min.8.2 Identify the time-temperature function (for example,5C/min heating rate) to be used in the test. Generate a curveof background deflection against
36、 temperature by performing ameasurement with the upper loading plate in contact with thelower support plate (pieces of platinum foil may be used forseparation) while operating the furnace under the chosentime-temperature function. The thickness change of the testspecimen is determined by algebraic s
37、ubtraction of this back-ground curve from the measured curve.8.3 Measure the specimen diameter and thickness with amicrometer to within 0.01 mm and record the results.8.4 To protect the parallel plates from reaction with thespecimen, sandwich the specimen between two platinum foilpieces and place th
38、e sandwich concentrically between theparallel plates. All platinum foil must be the same thicknessand suitably thin (preferably 25 m thick) so as to allow seatingof the components in their required position.8.5 Adjust the position of the extensometer to the lower endof its measuring range. Place the
39、 furnace in position and startthe chosen time-temperature function.8.6 When a usable deflection rate is reached, begin record-ing extensometer, time and temperature data to be used in datareduction. The collection interval should not exceed 1 min.Suitable means of accumulating data include computer-
40、controlled data acquisition or plotting the thickness change andtemperature of the specimen with a two pen recorder operatingon a convenient time base. (If such a recording device is notavailable and data must be taken manually, the thicknesschange and temperature may be recorded by taking readings
41、ofboth the extensometer and temperature alternately at 30-sintervals so that each will be read at 1-min. intervals. Becauseit is less accurate than the other methods, the user is discour-aged from using this method to acquire data.) If the extensom-eter goes off range during the test, reset it. Comp
42、ression of thesample to a thickness less than 1 mm is excessive.9. Calculation9.1 Use the corrected change in extensometer readings, dh,during a given time interval, dt, as the rate of thickness change,dh/dt, at the temperature corresponding to the middle of thatinterval. Also record the specimen th
43、ickness change, d,atthemidpoint of the time interval; use it to calculate the specimenthickness:h 5 h02 d (2)where:h0= the initial specimen thickness.Substitute those data into Eq 1 to calculate the viscosity, h.Correct the viscosity using the calibration curve (see Section 7)by multiplying the visc
44、osity by the fractional correction factorcorresponding to that viscosity.10. Report10.1 At a minimum, report the following information:10.1.1 Identification of the glass tested,10.1.2 Manufacturing source and date,10.1.3 Calibration reference,10.1.4 Temperature and viscosity points,10.1.5 Date of te
45、st and name of operator, and10.1.6 Other observations (for example, sample crystallizedduring measurement).11. Precision and Bias11.1 PrecisionIn the absence of round robin testing, aspecific precision statement cannot be made. However, Fon-tanas paper2describing the parallel plate method can be use
46、dto provide insight into the precision and bias of the test method.Precision can be estimated from the data scatter in mathemati-cal curve fitting of data.11.2 BiasIn general, this procedure should yield valuesfor viscosity points to 610 % of referenced SRM values.Systematic departures may occur for
47、 values obtained near thebeginning and end of the determination where the thicknesschange rates are small. A rigid test of the apparatus is tocalibrate with one NIST SRM glass and then measure otherNIST SRM glasses based on this calibration. If the otherstandard glass values are within 4C of certifi
48、cation, satisfac-tory performance has been established. If errors arise thatincrease or decrease with viscosity, a temperature measurementproblem may exist or thermal gradients in the furnace may betoo large. These should be corrected.5Fulcher, G. S., Journal of the American Ceramic Society , Vol 8,
49、 1925, pp.339355.C 1351M 96 (2007)312. Keywords12.1 glass; parallel plate; viscosityASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years
