1、Designation: C 1350M 96 (Reapproved 2003)METRICStandard Test Method forMeasurement of Viscosity of Glass Between Softening Pointand Annealing Range (Approximately 108Pas toApproximately 1013Pas) by Beam Bending (Metric)1This standard is issued under the fixed designation C 1350M; the number immediat
2、ely following the designation indicates 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 te
3、st method covers the determination of glassviscosity from approximately 108Pas to approximately 1013Pas by measuring the rate of viscous bending of a simplyloaded glass beam.2Due to the thermal history of the glass, theviscosity may not represent conditions of thermal equilibriumat the high end of t
4、he measured viscosity range. Measurementscarried out over extended periods of time at any temperature orthermal preconditioning will minimize these effects by allow-ing the glass to approach equilibrium structural conditions.Conversely, the method also may be used in experimentalprograms that focus
5、on nonequilibrium conditions.1.2 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 theresponsibility of the user of this standard to establish appro-priate safety and health
6、practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:C 336 Test Method for Annealing Point and Strain Point ofGlass by Fiber Elongation3C 338 Test Method for Softening Point of Glass3C 598 Test Method for Annealing Point and Stra
7、in Point ofGlass by Beam Bending3C 965 Practice for Measuring Viscosity of Glass Above theSoftening Point3C 1351M Test Method for Measurement of Viscosity ofGlass between 104Pas and 108Pas by Viscous Compres-sion of a Solid Right Cylinder Metric33. Terminology3.1 Definitions:3.1.1 beam bending visco
8、metera device used to determinethe viscosity of glass from approximately 108Pas to approxi-mately 1013Pas by measuring the deflection rate of a simplysupported beam. The equation for calculating viscosity by thismethod is:h5gL31440 Icdh/dt!FM 1rAL1.6GF1 1asT!31 1agT!4G(1)where:h = viscosity, Pas,M =
9、 load (applied load + loading train), gms,dh/dt = midpoint deflection rate of test beam, cm/s,g = acceleration of gravity, 980 cm/s2,Ic= cross-sectional moment of inertia, cm4,r = density of glass, g/cm3,A = cross-sectional area of the beam, cm2,L = support span, cm, andasand ag= mean coefficient of
10、 linear thermal expansionof support stand and glass, respectively, 25Cto temperature of measurement, T, m/m/C.See Note 1.NOTE 1The term (1 + asT)3/(1 + agT)4corrects for thermal expan-sion changes of room temperature dimensions. It can be ignored when asand agare approximately equal. A fused silica
11、support stand in combina-tion with a high expansion glass can make this term 3 % in magnitude.Only an estimate of agis required, singe the correction is small. Use 1.51This test method is under the jurisdiction of ASTM Committee C14 on Glassand Glass Products and is the direct responsibility of Subc
12、ommittee C14.04 onPhysical and Mechanical Properties.Current edition approved Apr. 10, 2003. Published July 2003. Originallyapproved in 1996. Last previous edition approved in 1996 as C 1350M 96.2Hagy, H. E., “Experimental Evaluation of Beam Bending Method of Deter-mining Glass Viscosities in the Ra
13、nge 108to 1015Poises”, Journal of the AmericanCeramic Society, Vol 46, No. 2, 1963, pp. 9597.3Annual Book of ASTM Standards, Vol 15.02.4The sole source of supply of flamebent hooks known to the committee at thistime is Insaco Inc., P.O. Box 422, Quakertown, PA 18951. If you are aware ofalternative s
14、uppliers, please provide this information to ASTM Headquarters. Yourcomments will receive careful consideration at a meeting of the responsibletechnical committee, which you may attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
15、times the room temperature coefficient if data are unavailable.4. Significance and Use4.1 This test method is well suited for measuring theviscosity of glasses in ranges higher than those covered byparallel plate (see Test Method C 1351) and rotational viscom-etry (see Practice C 965) methods. This
16、test method is usefulfor providing information related to the behavior of glass afterit has been formed into an object of commerce and in researchand development.5. Apparatus5.1 The apparatus shall consist of a furnace, a means ofcontrolling its temperature and heating rate, specimen holdersand load
17、ing rod, and a means of observing the rate of viscousdeflection of the glass specimen.5.2 Furnace:5.2.1 The furnace shall be electrically heated by resistanceelements. The dimensions and the details of the furnaceconstruction are not critical; its cross-section can be circular of75 mm (;3 in.) diame
18、ter or square with sides of 75 mm. Thefurnace should have a constant temperature zone that coversthe specimen geometry, including the deflection range. Differ-ences in temperature greater than 2C within that constanttemperature zone are unacceptable.5.3 Temperature Measuring and Indicating Instrumen
19、ts: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-bore alumina tubewith its junction placed within 5 mm of the specimen near theaxis of the furnace. The thermocouple shall be referenced to0C by m
20、eans of an ice bath, and its emf measured with acalibrated potentiometer that can be read with a sensitivity of0.1C and an accuracy of 60.5C. Precautions shall be taken toensure that the ice bath is maintained at 0C throughout thetest. Alternately, the output of the thermocouple can bemeasured on a
21、calibrated, direct reading meter (electronicthermometer) that can be read with a sensitivity of 0.1C andan accuracy of 60.5C. See Note 3 for temperature lag-leadcorrections.5.4 Furnace Control:5.4.1 Suitable means shall be provided for maintaining thefurnace temperature at a fixed control point and
22、for controllingthe heating and cooling rates. Commercially available pro-gramming equipment provides excellent control. A variabletransformer with manual control is an inexpensive, but lessadequate means of accomplishing the required control.5.5 Specimen Holder and Loading Rod:5.5.1 A diagram of the
23、 apparatus can be found in TestMethod C 598.5.5.2 A ceramic support stand and a ceramic loading rodshall be provided for supporting the specimen and applying theload to it. The thermal expansion characteristics of bothmembers must be very similar so as to minimize motion of theloading rod due to exp
24、ansion differences. A rectangular alu-mina muffle or circular tube that can be notched to definespecimen position is a suitable support stand (see Note 2). Thesupporting surfaces of these notches shall be flat and lie in aplane perpendicular to the axis of the furnace. The inside edgesof these notch
25、es define the support span once the specimenbeam starts to deflect. A support span of about 5 cm (62 in.)is recommended. A suitable loading rod can be provided by asingle-crystal sapphire rod flame bent at one end in the form ofa shepherds crook.4This crook will contribute to the load onthe specimen
26、, so its weight should be kept to a minimum.NOTE 2Vitreous silica is a suitable material for both support standand loading rod. It is not recommended for temperatures above 900C.5.6 Extensometer for Measuring Midpoint Deflection:5.6.1 The means for observing the rate of deflection of thespecimen sha
27、ll allow reliable reading of total deflection of atleast 10 mm. The extensometer shall permit direct reading of0.010 mm and estimates of 0.0010 mm. Its accuracy shall besuch that the error of indication will not exceed 62 % for anymeasured deflection. This will limit the minimum deflectionthat may b
28、e used in calculation. A linearly variable differentialtransformer (LVDT) is suitable for this purpose, as is any otherdevice (for example, optical or capacitive), provided thatdeflection is reliably measured as specified.5.7 Weights:5.7.1 A set of weights spanning the range from 1 to 500 gand accur
29、ate to 0.1 % relative is required.5.8 Micrometre Calipers:5.8.1 Micrometre calipers which can be read to an accuracyof at least 0.01 mm are required for measuring specimendimensions.5.9 Analytical Balance:5.9.1 An analytical balance capable of weighing the shep-herds crook and loading train to an ac
30、curacy of 0.1 % relative.6. Preparation of Test Specimen6.1 Specimens may either be flame drawn or centerlessground into cylindrical form or diamond-saw cut and millground into rectangular form. Nonuniformity of any dimensionalong the length of the specimen shall not exceed 2 %. Whennonuniformity of
31、 any dimension exists, an average value shallbe used.6.2 The numerical ratio of beam span to moment of inertiashall not be less than 60. The thickness or diameter to spanratio shall be less than 0.1.7. Calibration7.1 Direct calibration of the apparatus is accomplished byusing standard glasses, such
32、as those supplied and certified bythe National Institute of Standards and Technology (NIST),having known temperature values over the viscosity rangecovered by this practice.5Bias should be corrected by overallinstrument calibration:7.1.1 Determine the viscosity using test beams of an SRMglass which
33、cover a range of cross-sectional moments ofinertia. Determine the viscosity over the viscosity range of 108Pas to 1011Pas by following the standard procedure de-scribed in Sections 8 and 9. Carry out tests keeping span andtime-temperature function constant.5Table 2, Annual Book of ASTM Standards, Vo
34、l 15.02 NIST Special PublicationNo. 260.C 1350M 96 (2003)27.1.2 Mathematically fit resulting data to a convenient form(for example, polynomial or Fulcher6equation). 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 a
35、t 20C minimum intervals over the measuredrange. Determine the viscosity ratio, hSRM fit/hmeasuredfit = 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 gr
36、eater than 20 % are cause for 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, thecalibr
37、ation curve described in 7.1.3 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 fr
38、om the analysis of the same glass 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 t
39、he calibration correction to test data(Section 9).8. Procedure8.1 Deflection data may be taken under isothermal condi-tions or heating or cooling at controlled rates not to exceed5C/min.8.2 Identify the time-temperature function (for example,5C/min heating rate) to be used in the test. Use a sapphir
40、e oralumina specimen to generate a curve of background deflectionagainst temperature, using the chosen time-temperature func-tion intended for specimen measurement. The deflection of thetest specimen is then determined by algebraic subtraction ofthis background curve from the measured curve.8.3 Meas
41、ure the dimensions of the test beam to the nearest0.01 mm. Use this data to calculate the cross-sectional momentof inertia. (Formulae for common cross-sections are presentedin Appendix X1 of Test Method C 598.)8.4 To protect the support from reaction with the specimenand reduce friction between spec
42、imen and support, place a thinplatinum foil in each notch, then place the specimen beamacross the support stand at the notch points. Place a thinplatinum foil between the loading rod and the specimen. Allplatinum foil must be the same thickness, and suitably thin(preferably 25 m thick) so as to allo
43、w seating of thecomponents in their required position.8.5 Carefully engage the loading rod to the specimen andcenter it. Apply a weight to the hook on the end of theextensometer, adjusting the total, applied load (consisting ofthe specimen, loading rod, hooks, fixtures, and weight) so thata usable d
44、eflection rate is obtained. Adjust the position of theextensometer to the lower end of its measuring range. Startheating the furnace, using the time-temperature function cho-sen for measurements.8.6 When a usable deflection rate is attained, begin record-ing extensometer, time, and temperature data
45、to be used in datareduction. The collection interval should not exceed 1 min.Suitable means of accumulating data include computer-controlled data acquisition or plotting the deflection andtemperature of the specimen with a two pen recorder operatingon a convenient time base. (If such a recording dev
46、ice is notavailable and data must be taken manually, the deflection andtemperature may be recorded by taking readings of both theextensometer and temperature alternately at 30-s intervals sothat each will be read at 1-min. intervals. Because it is lessaccurate than the other methods, the user is dis
47、couraged fromusing this method to acquire data.) If the extensometer goes offrange during the test, reset it. Total beam deflections greaterthan 10 mm are excessive.9. Calculation9.1 Use the corrected change in extensometer readings, dh,during a given time interval, dt, as the rate of midpointdeflec
48、tion, dh/dt, at the temperature corresponding to themiddle of that interval. Substitute those data into Eq 1 tocalculate the viscosity, h. Correct viscosity using the calibra-tion curve (see Section 7) by multiplying the viscosity by thefractional correction factor corresponding to that viscosity.10
49、. 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 test 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, Hagyspaper3describing the beam bending method can provideinsight into the precision and bia
