1、Designation: E 2040 03Standard Test Method forMass Scale Calibration of Thermogravimetric Analyzers1This standard is issued under the fixed designation E 2040; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisi
2、on. 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 describes the calibration or perfor-mance confirmation of the mass (or weight) scale of thermo-gravimetric anal
3、yzers and is applicable to commercial andcustom-built apparatus.1.2 Electronic instrumentation or automated data analysisand reduction systems or treatments equivalent to this testmethod may be used.1.3 SI units are the standard.1.4 There is no ISO standard equivalent to this test method.1.5 This st
4、andard 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 practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1
5、 ASTM Standards:2E 473 Terminology Relating to Thermal AnalysisE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 1142 Terminology Relating to Thermophysical Properties3. Terminology3.1 DefinitionsSpecific technical terms used in this testmethod are de
6、fined in Terminologies E 473 and E 1142.4. Summary of Test Method4.1 The mass signal generated by a thermogravimetricanalyzer is compared to the mass of a reference materialtraceable to a national reference laboratory. A linear correlationusing two calibration points is used to relate the mass (orwe
7、ight) signal generated by the thermogravimetric analyzerand that of the reference material.5. Significance and Use5.1 This test method calibrates or demonstrates conformityof thermogravimetric apparatus at ambient conditions. Mostthermogravimetry analysis experiments are carried out undertemperature
8、 ramp conditions or at isothermal temperaturesdistant from ambient conditions. This test method does notaddress the temperature effects on mass calibration.5.2 In most thermogravimetry experiments, the masschange is reported as weight percent in which the observedmass at any time during the course o
9、f the experiment is dividedby the original mass of the test specimen. This method ofreporting results assumes that the mass scale of the apparatusis linear with increasing mass. In such cases, it may benecessary only to confirm the performance of the instrument bycomparison to a suitable reference.5
10、.3 When the actual mass of the test specimen is recorded,the use of a calibration factor to correct the calibration of theapparatus may be required, on rare occasions.6. Apparatus6.1 The essential equipment required to provide the mini-mum thermogravimetric analytical capability for this testmethod
11、includes the following:6.1.1 Thermobalance, composed of a furnace;atempera-ture sensor;abalance to measure the specimen mass with aminimum capacity within the range to be calibrated and asensitivity of 6 1 g; and a means of maintaining thespecimen/container under atmospheric control of the gas to be
12、used at a purge rate between 10 to 1006 5 mL/min.NOTE 1Excessive purge rates should be avoided as this may intro-duce noise due to bouyancy effects and temperature gradients.6.1.2 Temperature Controller, capable of maintaining am-bient temperature to 6 1K.6.1.3 Recording Device, capable of recording
13、 and display-ing any fraction of the specimen mass signal including thesignal noise, versus any faction of the temperature signalincluding noise.1This test method is under the jurisdiction of ASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on TestMet
14、hods and Recommended Practices.Current edition approved Sept. 10, 2003. Published November 2003. Originallyapproved in 1999. Last previous edition approved in 1999 as E 2040 99.2For referenced ASTM standards, visit the website,www.astm.org, or contactASTM Customer service at serviceastm.org. For Ann
15、ual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTMwebsite.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.1.4 Containers (pans, crucibles, etc.), which are inert tothe specimen an
16、d which will remain gravimetrically stable.7. Reagents and Materials7.1 A reference material of known mass, which is traceableto a national standards laboratory, such as the National Instituteof Standards and Technology (NIST). Such mass referencematerials are available from most general laboratory
17、equipmentsuppliers.7.2 The mass of the reference material should correspond tothe working range of the analysis. For most work, the massmaximumshould be 25 to 50 % greater than the material beingexamined.8. Calibration and Standardization8.1 Perform any mass signal calibration procedures recom-mende
18、d by the manufacturer of the thermogravimetric analyzeras described in the operators manual.9. Procedure9.1 Prepare the thermogravimetric analyzer for operationunder the test conditions to be used for the characterization oftest specimens, including loading an empty specimen containerand initiating
19、a purge gas. The temperature to be used isambient.9.2 Tare the apparatus by setting the mass of the emptyspecimen container to 0.00 mg.9.3 Open the apparatus, place the reference material into thespecimen container, and reassemble the apparatus under thetest conditions to be used for the characteriz
20、ation of the testspecimens.9.4 Record the mass observed by the apparatus as mo.9.5 Record the mass of the reference material from itscertificate as ms, retaining all available decimal places in themeasured value.9.6 Calculate and report the value for the slope (S) andconformity (C) using Eq 2 and Eq
21、 3.10. Calculation10.1 For the purpose of this test method, it is assumed thatthe relationship between observed mass (mo) and the referencemass (ms) is linear and governed by the slope (S)ofEq1:ms5 mo3 S! (1)10.2 By using the mass values taken from 9.4 and 9.5,calculate S using Eq 2.S 5 ms/ mo(2)NOT
22、E 2When performing this calculation, retain all available decimalplaces in the calculated value.10.3 Using the value of S from 10.2, the percent conformityof the instrument mass scale, C, may be calculated using Eq 3.C 51.00000 2 S!3100 % (3)NOTE 3The percent conformity usually is a very small numbe
23、r andexpressing it as a percent value may be inconsistent with SI metricnotation. Because of its effect on the experiment and because of commonuse, its expression as a percent is used in this procedure.10.3.1 Conformity may be estimated to one significantfigure using the following table of criteria:
24、10.3.1.1 If S is between 0.9999 and 1.0001, then conformityis better than 0.01 %.10.3.1.2 If S is between 0.9990 and 0.9999 or between1.0001 and 1.0010, then conformity is better than 0.1 %.10.3.1.3 If S is between 0.9900 and 0.9990 or between1.0010 and 1.0100, then conformity is better than 1 %.10.
25、3.1.4 If S is between 0.9000 and 0.9900 or between1.0100 and 1.1000, then conformity is better than 10 %.10.4 Report the value of S and the conformity, C.10.5 Using the determined value of S from Eq 2, Eq 1 maybe used to calculate the true corrected mass (m) from anobserved mass (mo).11. Report11.1
26、The report shall include the following information:11.1.1 Details and description, including the manufacturerand instrumental model number, where applicable, of thethermogravimetric analyzer.11.1.2 The value of S as determined in 10.2, reported to atleast four places to the right of the decimal poin
27、t.11.1.3 The conformity, C, as determined in 10.3.11.1.4 The specific dated version of this method used.12. Precision and Bias12.1 An interlaboratory study was conducted in 1998 thatincluded participation by seven laboratories using instrumentsfrom a single manufacturer (TA Instruments). The results
28、 weretreated by Practice E 691.12.2 Precision:12.2.1 The mean value for the calibration constant was S =0.99818.12.2.2 The repeatability (within laboratory) standard devia-tion for S was 0.00047.12.2.3 Two values, each the mean of duplicated determina-tions within a single laboratory, should be cons
29、idered suspect ifthey differ by more than 95 % repeatability limit r = 0.0013.12.2.4 The reproducibility (between laboratory) standarddeviation for S was 0.0030.12.2.5 Two values, each the mean of duplicated determina-tions in differing laboratories, should be considered suspect ifthey differ by mor
30、e than 95 % reproducibility limit R = 0.0084.12.3 Bias:12.3.1 The measurement of conformity in this test method isa comparison of the calibration constant S with the theoreticalvalue of 1.0000000 and provides an indication of bias.12.3.2 The mean value for conformity was C = 0.18 %.12.3.3 Conformity
31、 was found to vary widely among instru-ment models but in no case exceeded C = 0.66 %. This valueis far better than the nominal conformity of 1 % required formost thermal analysis experiments.13. Keywords13.1 calibration; conformity; mass; thermogravimetry; ther-mogravimetric analyzerE2040032ASTM In
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35、tandards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).E2040033
