1、Designation: E1582 14Standard Practice forCalibration of Temperature Scale for Thermogravimetry1This 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 revision. A
2、 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 practice describe the temperature calibration ofthermogravimetric analyzers over the temperature range from25 to 1500C and is app
3、licable to commercial and custom-builtapparatus. This calibration may be accomplished by the use ofeither melting point standards or magnetic transition standards.1.2 The mass change curve in thermogravimetry resultsfrom a number of influences, some of which are characteristicof the specimen holder
4、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, and the ac
5、curacy and sensitivity of thetemperature sensor and displaying scales. These all contributeto differences in measured temperatures, which may exceed20C. In addition, some sample holder assemblies will showvariations of measured temperature with sample size orheating/cooling rate, or both. Since it i
6、s 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 correction t
7、erm to subsequentmeasurements.1.3 This practice assumes that the indicated temperature ofthe 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 experimentalmeasurements to be mad
8、e as possible.1.4 This practice describes two procedures for temperaturecalibration of thermogravimetric analyzers using any typebalance. Procedure A uses melting point standards for calibra-tion. Procedure B uses magnetic transition standards forcalibration.NOTE 1Since all electronic data treatment
9、s are not equivalent, the usershall verify equivalency prior to use.1.5 The data generated by these procedures can be used tocorrect the temperature scale of the instrument by either apositive or negative amount using either a two-point tempera-ture calibration procedure or a multi-point temperature
10、 calibra-tion with best line fit for the generated data.NOTE 2A single-point calibration may be used where this is the onlyprocedure possible or practical. The use of a single-point procedure is notrecommended.1.6 The values stated in SI units are to be regarded asstandard. No other units of measure
11、ment are included in thisstandard.1.7 This practice is related to ISO 11358 but providesinformation and methods not found in ISO 11358.1.8 This standard does not purport to address all of thesafety problems, if any, associated with its use. It is theresponsibility of the user of this standard to est
12、ablish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E473 Terminology Relating to Thermal Analysis and Rhe-ologyE691 Practice for Conducting an Interlaboratory Study toDetermine the Precisio
13、n of a Test MethodE967 Test Method for Temperature Calibration of Differen-tial Scanning Calorimeters and Differential Thermal Ana-lyzersE1142 Terminology Relating to Thermophysical Properties2.2 Other Standards:ISO 11358 Plastics Part 4: Thermogravimetry (TG) ofPolymers General Principles33. Termin
14、ology3.1 DefinitionsTechnical terms used in this document aredefined in Terminologies E473 and E1142.1This practice is under the jurisdiction of ASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on Calo-rimetry and Mass Loss.Current edition approved Ma
15、y 1, 2014. Published June 2014. Originallyapproved in 1993. Last previous edition approved in 2010 as E1582 10. DOI:10.1520/E1582-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer service at serviceastm.org. For Annual Book of ASTMStandards volume infor
16、mation, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. U
17、nited States13.1.1 magnetic reference temperaturethe 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 TG curve as thepoint of intersection of the extrapolated higher temperat
18、ureportion of the base line with a tangent drawn to the point ofgreatest slope of apparent mass-change curve. This tempera-ture most closely represents the Curie Point, that point on themass change curve where the magnetic effect of the standardmaterial has disappeared completely (see Fig. 1).3.1.1.
19、1 DiscussionThe position of the magnet and thedesign of the instrument will affect the direction of the masschange.4. Summary of Practice4.1 This practice provides a set of different procedures sincethermogravimetric apparatus is often of significantly differingdesign.4.2 Calibration of Analyzers Us
20、ing 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. 2) is determined andcompared with the established
21、 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 to nonmagnetic transitionin the presence of a magne
22、tic field.4.3 Calibration of Analyzers That Have SimultaneousThermogravimetry-Differential Scanning Calorimeter orThermogravimetry-Differential Thermal Analysis CapabilityThese instruments may be calibrated using melting temperaturestandards following Practice E967.5. Significance and Use5.1 Thermog
23、ravimetric 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 temperature axis (abscissa) of allapparent-mass-chang
24、e 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 use of either melting point or magnetictransition s
25、tandards.5.2 This practice permits interlaboratory comparison andintralaboratory correlation of instrumental temperature scaledata.6. Interferences6.1 The reference metals are sensitive to impurities and mayoxidize at elevated temperatures.All runs shall be conducted inan oxygen-free inert purge gas
26、 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 rate,and heating will affect the calibration. These rates
27、 and condi-tions must be the same for both calibration and analysis. Inaddition, high heating rates should be avoided, if possible. Dueto the differing heat exchange (emissivity and heat capacity)during the calibration and analysis, higher heating rates in-crease the error in the temperature measure
28、ment. The ICTACSixth International Test Program (1)4warns that heating ratesabove 6C/min can produce errors in the temperature calibra-tion.7. Apparatus7.1 Thermogravimetric AnalyzerA system of related in-struments that are capable of continuously measuring the massof a specimen in a controlled atmo
29、sphere and in a controlledtemperature environment ranging from ambient to at least25C above the temperature range of interest over a selectedtime period. This instrument shall consist of the following:7.1.1 Thermobalance, composed of:7.1.1.1 Furnace, to provide uniform controlled heating of aspecime
30、n from 25C to a constant temperature or at a constantrate within the applicable temperature range of this practice.7.1.1.2 Temperature Sensor, to provide an indication of thespecimen/furnace temperature to 60.1C.7.1.1.3 A continuously recording Balance, to measure thespecimen weight with a minimum c
31、apacity of 50 mg and asensitivity of 65 g.4The boldface numbers in parentheses refer to a list of references at the end ofthis standard.FIG. 1 Magnetic Reference TemperatureE1582 1427.1.1.4 A means of maintaining the specimen/containerunder Atmospheric Control, of nitrogen or other inert gas of99.9
32、+% purity at a purge rate of 50 to 100 mL/min constant towithin 65 mL/min.7.1.2 A Temperature Controller, capable of executing aspecific temperature program by operating the furnace betweenselected temperature limits at a specified heating rate between0.5 to 20C/min constant to within 60.1C/min or t
33、o anisothermal temperature that is maintained constant to 60.5Cfor a minimum of 10 min.7.1.3 ARecording Device, capable of recording and display-ing any fraction of the specimen weight (TGA thermal curve)including the signal noise, on the Y-axis versus any fraction oftemperature, including signal no
34、ise, on the X-axis.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.8. Calibration and Standardization8.1 Calibration of ApparatusIf necessary, calibrate thetemperature sensor of the
35、instrument at room temperature usingthe procedure described in the instrument manual.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 forcalibration.NOTE 3The
36、 melting temperatures of the first seven materials given inthis table are taken from Mangum and Furukawa (2) and have beenselected as primary fixed points for the International Temperature Scale of1990. The remaining melting temperatures give in this table are takenfrom Bedford, Bonnier, Mass, and P
37、avese (3).8.2.2 Magnetic Transition Standards.NOTE 4Materials with known magnetic transitions determined withhigh precision are required (4). For sources of materials of known orcertified Curie transition temperatures, contact the ASTM InformationCenter. The values for Curie transition temperatures
38、differ from lot to lotof the material. Curie point temperatures given in Table 2 were obtainedfrom Ref. (5).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 adju
39、sted.9.2 Standard Preparation Procedure:9.2.1 Press the metal standard 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
40、at the selectedflow rate. Select the heating rate that will be used in 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 syst
41、em.9.2.5 Rapidly heat the system to 50C below the theoreticalmelting temperature, and allow the system to equilibrate for 5minutes. Then heat at the selected programmed rate up throughFIG. 2 Sample Positioning for Procedure ATABLE 1 Recommended Melting Temperature StandardsCalibration Material Melti
42、ng 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 (1357.77)NickelB1455 (1728)PalladiumB1554.8 (1828.0)PlatinumB1768.2 (2041.3)APrimary fixed points, ITS-90 (2).BSecondary ref
43、erence points, ITS-90 (3).TABLE 2 Curie Temperature StandardsA,BMetalCurie Point (Magnetic) Transition,CALUMEL (trademark)A152.6NickelB358.2Nickel (83%)-Cobalt (17%) 554.4Nickel (63%)-Cobalt (37%) 746.4Nickel (37%)-Cobalt (63%) 930.8Cobalt 1116AAvailable from TA Instruments, 109 Lukens Drive, New Ca
44、stle, DE., the onlyknown source of certified and traceable Curie Temperature Reference Materials.Interested parties are invited to submit information regarding the identification ofacceptable alternatives to the Committee on Standards. ASTM InternationalHeadquarters, 100 Barr Harbor Drive, West Cons
45、hohocken, PA 194282959.BFrom Ref. (5).E1582 143the 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 inFig. 3.9.2.6 Measure the onset temperature of the endothermicheat flo
46、w peak.10. Procedure BMagnetic Transition StandardCalibration10.1 For those systems using internal microfurnaces with anadjustable temperature sensor, it shall be adjusted so that it isjust beneath (but not touching) the thermogravimetric analyzerspecimen container (see Figs. 4 and 5).10.2 Close the
47、 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 that in which one would place a specimen. Closethe system.10.4 P
48、lace 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 me
49、asurable apparent mass change occurs.NOTE 5The choice of magnets or magnetic fields should be made sothat at least a 2 % change in apparent mass is observed by turning the fieldon and off.10.4.1 Adjust the specimen size or mass loss sensitivity, ifnecessary, and replace (or turn on) the magnet.10.5 Rapidly heat the magnetic transition standard to atemperature at least 50C below the transition temperature ofthe standard and hold that temperature for 5 min.10.6 Heat the test specimen at the desired heating ratethrough the transition temperature regi
