ASTM E1582-17 Standard Test Method for Temperature Calibration of Thermogravimetric Analyzers.pdf

1、Designation: E1582 17Standard Test Method forTemperature Calibration of Thermogravimetric Analyzers1This standard is issued under the fixed designation E1582; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio

2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method describe the temperature calibration ofthermogravimetric analyzers over the temperature range from25 to 1500 C a

3、nd is applicable to commercial and custom-built apparatus. This calibration may be accomplished by theuse of either melting point standards or magnetic transitionstandards.1.2 The weight change curve in thermogravimetry resultsfrom a number of influences, some of which are characteristicof the speci

4、men holder assembly and atmosphere rather thanthe specimen. The variations from instrument to instrumentoccur in the point of measurement of the temperature, thenature of the material, its size and packing, the geometry andcomposition of the specimen container, the geometry anddesign of the furnace,

5、 and the accuracy and sensitivity of thetemperature sensor and displaying scales. These all contributeto differences in measured temperatures, which may exceed 20C. In addition, some sample holder assemblies will showvariations of measured temperature with sample size orheating/cooling rate, or both

6、. Since it is neither practical noradvisable to standardize sample holders or thermobalancegeometries, instruments may be calibrated by measurement ofthe deviation of a melting or magnetic (Curie Point) transitiontemperature from the standard reference temperature. Thisdeviation can be applied as a

7、correction term to subsequentmeasurements.1.3 This test method assumes that the indicated temperatureof the instrument is linear over the range defined by a two-pointcalibration and that this linearity has been verified. These twocalibration temperatures should be as close to the experimentalmeasure

8、ments to be made as possible.1.4 This test method describes two procedures for tempera-ture calibration of thermogravimetric analyzers using any typebalance. Procedure A uses melting point standards for calibra-tion. Procedure B uses magnetic transition standards forcalibration.1.5 The data generate

9、d by these procedures can be used tocorrect the temperature scale of the instrument by either apositive or negative amount using either a one- or two-pointtemperature calibration procedure.1.6 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in

10、thisstandard.1.7 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, health, and environmental practices and deter-mine the applicability of regulatory limitations

11、 prior to use.1.8 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization Techni

12、calBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E473 Terminology Relating to Thermal Analysis and Rhe-ologyE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE967 Test Method for Temperature Calibration of Differen-tial Sca

13、nning Calorimeters and Differential Thermal Ana-lyzersE1142 Terminology Relating to Thermophysical PropertiesE2040 Test Method for Mass Scale Calibration of Thermo-gravimetric Analyzers3. Terminology3.1 DefinitionsTechnical terms used in this document aredefined in Terminologies E473 and E1142, incl

14、uding Celsius,Curie temperature, derivative, Kelvin, magnetictransformation, onset point, thermogravimetry, and thermo-gravimetric analyzer.1This test method is under the jurisdiction ofASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on Calo-rimetry

15、and Mass Loss.Current edition approved Oct. 1, 2017. Published October 2017. Originallyapproved in 1993. Last previous edition approved in 2014 as E1582 14. DOI:10.1520/E1582-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer service at serviceastm.org.

16、For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis

17、international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT

18、) Committee.13.1.1 magnetic reference temperature, nthe observed tem-perature at which a change in the magnetic properties of amaterial in a magnetic field produces an apparent mass change.This temperature is read from the dynamic thermogravimetrycurve as the point of intersection of the extrapolate

19、d highertemperature portion of the base line with a tangent drawn to thepoint of greatest slope of apparent mass-change curve. Thistemperature most closely represents the Curie Point, that pointon the mass change curve where the magnetic effect of thestandard material has disappeared completely (see

20、 Fig. 1).3.1.1.1 DiscussionThe position of the magnet and thedesign of the instrument will affect the direction of the masschange.4. Summary of Practice4.1 This test method provides a set of different proceduressince thermogravimetric apparatus is often of significantlydiffering design.4.2 Calibrati

21、on of Analyzers Using Magnetic TransitionStandards:4.2.1 In this procedure, the apparent mass change of one ormore of the magnetic transition standards is obtained under thenormal operating conditions of the instrument. The extrapo-lated endpoint temperature (see Fig. 1) is determined andcompared wi

22、th the established transition temperature for thematerial. The difference provides an adjustment or calibrationthat may be applied to the temperature scale of the instrument.4.2.2 The apparent mass change of the magnetic transitionmaterials is caused by the magnetic (ferromagnetic) to non-magnetic (

23、paramagnetic) transition in the presence of a mag-netic field.4.3 Calibration of Analyzers That Have SimultaneousThermogravimetry-Differential Scanning Calorimeter orThermogravimetry-Differential Thermal Analysis CapabilityThese instruments may be calibrated using melting temperaturestandards follow

24、ing Practice E967.5. Significance and Use5.1 Thermogravimetric analyzers are used to characterize abroad range of materials. In most cases, one of the desiredvalues to be assigned in thermogravimetric measurements isthe temperature at which significant changes in specimen massoccur. Therefore, the t

25、emperature axis (abscissa) of allapparent-mass-change curves must be calibrated accurately,either by direct reading of a temperature sensor, or by adjustingthe programmer temperature to match the actual temperatureover the temperature range of interest. In the latter case, this isaccomplished by the

26、 use of either melting point or magnetictransition standards.5.2 This test method permits interlaboratory comparisonand intralaboratory correlation of instrumental temperaturescale data.6. Interferences6.1 The reference metals are sensitive to impurities and mayoxidize at elevated temperatures.All r

27、uns shall be conducted inan oxygen-free inert purge gas of the same type to be used inthe experimental procedures.6.2 Care must be taken to stay below temperatures at whichthe magnetic transition standard will react with the specimen orits holder.6.3 The atmosphere, purge gas type, purge gas flow ra

28、te,and heating rate will affect the calibration. These rates andconditions must be the same for both calibration and analysis.In addition, high heating rates should be avoided, if possible.Due to the differing heat exchange (emissivity and heatcapacity) during the calibration and analysis, higher he

29、atingrates increase the error in the temperature measurement.7. Apparatus7.1 Thermogravimetric AnalyzerA system of related in-struments that are capable of continuously measuring the massof a specimen in a controlled atmosphere and in a controlledtemperature environment ranging from ambient to at le

30、ast 25C above the temperature range of interest over a selected timeperiod. This instrument shall consist of the following:7.1.1 Thermobalance, composed of:7.1.1.1 Furnace, to provide uniform controlled heating of aspecimen from 25 C to a constant temperature or at a constantrate within the applicab

31、le temperature range of this testmethod.7.1.1.2 Temperature Sensor, to provide an indication of thespecimen/furnace temperature to 60.1 C.7.1.1.3 A continuously recording Balance, to measure thespecimen apparent mass with a minimum capacity of 50 mgand a sensitivity of 65 g.7.1.1.4 A means of mainta

32、ining the specimen/containerunder Atmospheric Control, of nitrogen or other inert gas of99.9 +% purity at a purge rate of 50 mL/min to 100 mL/minconstant to within 65 mL/min.7.1.2 A Temperature Controller, capable of executing aspecific temperature program by operating the furnace betweenselected te

33、mperature limits at a specified heating rate between0.5 C/min to 20 C/min constant to within 60.1 C/min or toan isothermal temperature that is maintained constant to 60.5C for a minimum of 10 min.7.1.3 A Data Collection Device, to provide a means ofacquiring, storing, and displaying measured or calc

34、ulatedsignals, or both. The minimum output signals required forthermogravimetery are weight, temperature, and time.7.1.4 Containers (pans, crucibles, and the like), that areinert to the specimen and will remain dimensionally stablewithin the temperature limits of this test method.FIG. 1 Magnetic Ref

35、erence TemperatureE1582 1727.2 For the Magnetic Transition Method, a means of apply-ing a magnetic field sufficient to producea2%weight changein the test specimen.8. Calibration and Standardization8.1 Calibration of ApparatusIf necessary, calibrate themass base and temperature sensors of the instrum

36、ent at roomtemperature using the procedure described in the instrumentmanual or Test Method E2040.8.2 Calibration Materials:8.2.1 Melting Point StandardsFor the temperature rangecovered by many applications, the melting transition of the99.9+% pure materials listed in Table 1 may be used forcalibrat

37、ion.NOTE 1The values in Table 1 were determined using special 99.9999% pure materials and highly accurate steady-state conditions that are notattainable with this test method. The actual precision of this test methodis given in Section 13.8.2.2 Magnetic Transition Standards.NOTE 2Materials with know

38、n magnetic transitions determined withhigh precision are required (3).3For sources of materials of known orcertified Curie transition temperatures, contact the ASTM InformationCenter. The values for Curie transition temperatures differ from lot to lotof the material. Curie point temperatures given i

39、n Table 2 were obtainedfrom Ref. (4).9. Procedure AMelting Point Standard Calibration9.1 Positioning of the Temperature Sensor (Thermocouple):9.1.1 The temperature sensor is an integral part of thesample holder and cannot be adjusted.9.2 Standard Preparation Procedure:9.2.1 Press the metal standard

40、flat and place it in the middleof the crucible. Place the sample/crucible on the center of thesample holder (sensor), see Fig. 2.9.2.2 Close the balance assembly. Purge the balance andfurnace tube with the desired atmosphere and at the selectedflow rate. Select the heating rate that will be used in

41、subsequentanalyses. See 6.3.9.2.3 Adjust the balance so that it now gives a zero masssignal.9.2.4 Open the system and carefully suspend a platinummass of approximately 50 mg from the end of the wirestandard.9.2.4.1 Close the system.9.2.5 Rapidly heat the system to 50 C below the theoreticalmelting t

42、emperature, and allow the system to equilibrate for 5minutes. Then heat at the selected programmed rate up throughthe melting temperature of the standard. When the standardmelts, the heat flow signal will show and endothermic peak asis typically seen with a traditional. A typical curve is shown inFi

43、g. 3.9.2.6 Measure the onset temperature of the endothermicheat flow peak.10. Procedure BMagnetic Transition StandardCalibration10.1 For those systems using internal microfurnaces with anadjustable temperature sensor, it shall be adjusted so that it is3The boldface numbers in parentheses refer to a

44、list of references at the end ofthis standard.TABLE 1 Recommended Melting Temperature StandardsCalibration Material Melting Temperature, C (K)IndiumA156.5985 (429.7485)TinA231.928 (505.078)ZincA419.527 (692.677)AluminumA660.323 (933.473)SilverA961.78 (1234.93)GoldA1064.18 (1337.33)CopperA1084.62 (13

45、57.77)NickelB1455 (1728)PalladiumB1554.8 (1828.0)PlatinumB1768.2 (2041.3)APrimary fixed points, ITS-90 (1).BSecondary reference points, ITS-90 (2).TABLE 2 Curie Temperature StandardsA,BMetalCurie Point (Magnetic) Transition,CALUMEL (trademark)A152.6NickelB358.2Nickel (83 %)Cobalt (17 %) 554.4Nickel

46、(63 %)Cobalt (37 %) 746.4Nickel (37 %)Cobalt (63 %) 930.8Cobalt 1116AAvailable from TA Instruments, 109 Lukens Drive, New Castle, DE., the onlyknown source of certified and traceable Curie Temperature Reference Materials.Interested parties are invited to submit information regarding the identificati

47、on ofacceptable alternatives to the Committee on Standards. ASTM InternationalHeadquarters, 100 Barr Harbor Drive, West Conshohocken, PA 194282959.BFrom Ref. (4).FIG. 2 Sample Positioning for Procedure AFIG. 3 Heat Flow Curve for Procedure AE1582 173just beneath (but not touching) the thermogravimet

48、ric analyzerspecimen container (see Figs. 4 and 5).10.2 Close the system, adjust the atmospheric flow rate tothe selected rate, and zero the balance and chart recorder ifused.10.3 Open the system and place a specimen of the magnetictransition material in the specimen container in the sameposition as

49、 that in which one would place a specimen. Closethe system.10.4 Place a permanent magnet or electromagnet outside thefurnace in a position as close to the furnace and specimencontainer as is practical in order to affect an apparent masschange at the reference material transition temperature. Re-move (or turn off) the magnet to ascertain whether a conve-niently measurable apparent mass change occurs.NOTE 3The choice of magnets or magnetic fields should be so that anapparent mass change of up to2%isobserved by turning the field on andoff.10.4.1 Adjust th