1、Designation: D5483 05 (Reapproved 2015)Standard Test Method forOxidation Induction Time of Lubricating Greases byPressure Differential Scanning Calorimetry1This standard is issued under the fixed designation D5483; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, the year of last revision. A 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 test method covers the determination of oxidationinduction time of lu
3、bricating greases subjected to oxygen at3.5 MPa (500 psig) and temperatures between 155 C and210 C.1.2 The values stated in SI units are to be regarded asstandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any,
4、 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 ASTM Standards:2E473 Terminology Relating to Thermal Analysis and Rh
5、e-ology3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 extrapolated onset time, na time determined on athermal curve, as the intersection of the extrapolated baselineand a line tangent to the oxidation exotherm constructed at itsmaximum rate.3.1.2 oxidation induction time (OIT
6、), n the period of timefrom the first exposure to an oxidizing atmosphere until theextrapolated onset time.3.1.3 pressure differential scanning calorimeter, (PDSC),na differential scanning calorimeter, as defined in Terminol-ogy E473, that is capable of maintaining the test sample at acontrolled, el
7、evated pressure.3.1.4 thermal curve, na graph of sample heat flow versustime.4. Summary of Test Method4.1 A small quantity of grease is weighed into a sample panand placed in a test cell. The cell is heated to a specifiedtemperature and then pressurized with oxygen. The cell is heldat a regulated te
8、mperature and pressure until an exothermicreaction occurs. The extrapolated onset time is measured andreported as the oxidation induction time for the grease underthe specified test temperature.4.2 A kinetic equation incorporated with this test methodcan estimate oxidation induction times at other t
9、emperatures.5. Significance and Use5.1 Oxidation induction time, as determined under theconditions of this test method, can be used as an indication ofoxidation stability.3This test method can be used for researchand development, quality control and specification purposes.However, no correlation has
10、 been determined between theresults of this test method and service performance.6. Apparatus6.1 Pressure Differential Scanning Calorimeter (PDSC),equipped with the following items (see Fig. 1).4NOTE 1At the time that the round robin data for this test method wasgenerated, only TA Instruments4manufac
11、tured equipment that met therequirements of 5.1. Subsequently, other companies have manufacturedequipment meeting these requirements. Their use is permitted providedtheir performance is consistent with the repeatability and reproducibilitydescribed in Section 10.6.1.1 Sample Enclosure, with capabili
12、ty to 3.5 MPa(500 psig) at 210 C and pressure gauge graduated at intervalsof 200 kPa (28.6 psi) or less.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.09.0E on Oxidation of Greas
13、es.Current edition approved Oct. 1, 2015. Published December 2015. Originallyapproved in 1993. Last previous edition approved in 2010 as D5483 05 (2010).DOI: 10.1520/D5483-05R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.
14、For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Rhee, In-Sik, “Development of a New Oxidation Stability Test Method forGreases Using a Pressure Differential Scanning Calorimeter (PDSC),” NLGISpokesman, Vol 55, No. 4, July 1991, pp
15、. 123132.4The sole source of supply of the apparatus known to the committee at this timeis TA Instruments, Inc., 109 Lukens Drive, New Castle, DE 19720. If you are awareof alternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful con
16、sideration at a meeting of theresponsible technical committee,1which you may attend.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.2 Thermal Analyzer.6.3 Aluminum Sample Solid Fat Index (SFI), pan (see Note2).6.4 Oxidation Stabilit
17、y Software.6.5 Calibration Software.6.6 Flowmeter, with a capacity of at least 200 mL min.6.7 Sample Encapsulation Press.NOTE 2It has been found that grease samples can be prepared withmore consistent surface areas using SFI pans as compared to flat bottompans, resulting in better reproducibility.NO
18、TE 3See Fig. 1 for a diagram of a typical test unit.7. Reagents and Materials7.1 Oxygen, extra dry, of not less than 99.5 % purity byvolume. (WarningOxidizer. Gas under pressure. In additionto other precautions, use stainless steel or copper tubing whichis compatible with oxygen, and pressure gauges
19、 which aredesignated for use with oxygen.)7.2 Indium, of not less than 99.9 % purity by mass.8. Calibration8.1 Sample Temperature Calibration:8.1.1 Weigh approximately 10 mg of indium into an alumi-num sample pan, insert a lid and crimp the lid to the pan usingthe encapsulation press. Place the crim
20、ped pan onto the sampleplatform in the pressure cell. Seal an empty pan in the samemanner and place it on the reference platform. Set the cellcover in place and close the cell.8.1.2 Open the oxygen cylinder valve slightly and set apressure of 3.5 MPa 6 0.2 MPa (500 psig 6 25 psig) on thecell inlet l
21、ine with the pressure regulator. Partially open theinlet valve on the cell and allow the pressure to slowly build upin the cell. This should require approximately 2 min. Using theoutlet valve, adjust the oxygen purge rate through the flowme-ter to 100 mL min 6 10 mL min. The open position of theseva
22、lves should remain fixed during the test.8.1.3 Set the thermal analyzer to heat from ambient tem-perature (approximately 22 C) to 180 C) at a programmedrate of 10 C min. After completion of the run, measure themelting temperature of the indium. If the melting temperaturediffers from 157.4 C 6 0.2 C
23、(see Note 4), correct thedifference by using either the hardware or software calibrationprocedure described in the manufacturers instruction manual.If the hardware calibration procedure is used, the temperaturecorrection should be performed under 3.5 MPa (500 psig)oxygen pressure with a 100 mL min p
24、urge rate. A typicalmelting calibration curve is shown in Fig. 2.NOTE 4The melting temperature of indium is 156.6 C at atmosphericpressure, but has been found to be elevated to 157.4 C under theconditions of this test method, 3.5 MPa (500 psig) of oxygen.58.2 Temperature Controller Calibration:8.2.1
25、 Remove both the sample pan and the reference panfrom the cell, then close the cell. Slowly pressurize the cellwith 3.5 MPa 6 0.2 MPa (500 psig 6 25 psig) oxygen andadjust the purge rate to 100 mL min 6 10 mL min using thecell outlet valve. Select the desired test temperature (either210 C, 180 C, or
26、 155 C).8.2.2 Program the cell to maintain the selected test tempera-ture. If, after 10 min, the displayed cell temperature differs bymore than 60.2 C from the selected temperature, slowlyadjust the temperature controller until they agree.After makingan adjustment, wait at least 5 min to make certai
27、n that thetemperature is stable before continuing.8.2.3 Some of the newest instruments do not need this stepdue to their automatic calibration system. Therefore, thecontrol thermocouple calibaration should be performed accord-ing to the instruments manual.8.3 Cell Base Pressure Gauge CalibrationThe
28、calibrationshould be conducted using a calibrated pressure transducer ora previously calibrated gauge according to the pressure cellmanufacturers instructions.9. Procedure9.1 Before starting a test, the control thermocouple calibra-tion shall be conducted at the test temperature (either 210 C,180 C,
29、 or 155 C) according to 8.2.1 and 8.2.2. When the testtemperature is not known, the calibration should be conductedat 210 C. Ignore this step if the instrument already has anautomatic temperature controller calibration system.9.2 Weigh 2.0 mg 6 0.1 mg of grease into a sample pan.Spread the sample ev
30、enly upon the flat portion. Do not spillany of the sample into the trough portion of the pan (See Fig.3).NOTE 5Examples of suitable and poor sample on pan patterns areshown in Fig. 3.9.3 Place the uncovered pan containing the sample onto theplatform of the cell according to the PDSC manufacturersins
31、tructions for placing the sample pan. Place an empty pan ofthe same configuration onto the cell platform according to thePDSC manufacturers instructions for placing the referencepan. Close the cell and the pressure release valve.9.4 Beginning at ambient temperature (approximately22 C), program the s
32、ample temperature to increase at a rate of100 C min to the test temperature.5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1007.FIG. 1 PDSC Test UnitD5483 05 (2015)29.5 Allow the sample to equilibrate at the test temperatur
33、efor 2 min.NOTE 6This step did not appear in the test method which was used inthe round robin to generate the precision statement. The round robin testmethod used the software of a PDSC manufacturer to determine whenequilibration at test temperatures occurred. Step 9.5 removes this depen-dence on on
34、e PDSC manufacturer and is not expected to significantlyaffect the measured OIT since this step precedes the pressurization of thetest cell with oxygen.9.6 Open the oxygen valve and slowly pressurize the cell to3.5 MPa 6 0.2 MPa (500 psig 6 25 psig). This should requireapproximately 2 min to reach m
35、aximum pressure. The oxida-tion induction time is measured from the time when the oxygenvalve is opened.9.7 As soon as the pressure has equilibrated, check the cellpurge rate and adjust to 100 mL min 6 10 mL min with theoutlet valve.9.8 After a duration of 120 min from the time when theoxygen valve
36、was opened, close the oxygen valve and slowlyrelease the cell pressure by opening the cell pressure releasevalve. In the case of a sample for which the approximateoxidation induction time is known, the test can be stopped afterthe oxidation exotherm has occurred.9.9 Plot the thermal curve and measur
37、e the extrapolatedonset time for the oxidation exotherm. Report this time, to thenearest tenth of one minute, as the oxidation induction time forthe sample. If more than one oxidation exotherm is observed,record the oxidation induction time for the largest exotherm(See Fig. 4).NOTE 7A typical therma
38、l curve is shown in Fig. 4.9.10 If the induction time is less than 10 min, rerun the testat the next lower temperature, starting at 9.2. Allow the cell tocool to ambient temperature before running the test at the nextlower temperature.9.11 After the oxidation induction time requirement speci-fied in
39、 9.10 is satisfied, perform a duplicate test.9.12 If the difference between the two results is greater thanthe 95 % determinability limit stated in the Precision and Biassection of this test method (Section 12), then reject the resultsand determine two more oxidation induction times for thegrease by
40、 returning to . Otherwise, average the oxidationinduction times of both runs.10. Calculation of Induction Times for OtherTemperatures10.1 After an oxidation induction time has been determinedfor a particular grease, a value can be estimated for othertemperatures using the following equation:t 5 Aexp
41、17500/T! (1)where:t = estimated oxidation induction time, min,A = oxidation coefficient of the grease, andT = temperature, K (for desired temperature).The oxidation coefficient (A) is constant for a given greaseand is calculated by (Eq 1) using the oxidation induction timereported in 9.1.2, thus,A 5
42、 oxidation induction time/exp17500/test temperature, K!. (2)The estimated oxidation induction time can be used as aguide for choosing appropriate alternative test temperatures forFIG. 2 CalibrationFIG. 3 Sample Preparation on SFI PanD5483 05 (2015)3a grease. The estimated oxidation induction time is
43、 not a partof the report for this test method.11. Report11.1 Report the following information:11.1.1 Report, to the nearest tenth of one minute, theaverage value calculated in 9.12 as the oxidation inductiontime (OIT) for the sample.11.1.2 Report the test temperature.12. Precision and Bias612.1 The
44、precision of this test method as determined by thestatistical examination of interlaboratory test results involvingeleven samples, five laboratories, three test temperatures(155 C, 180 C, and 210 C), and oxidation induction times offrom 9.0 min to 45.3 min is as follows.12.1.1 Determinability The di
45、fference between the pair ofdeterminations averaged to obtain a test result would, in thelong run, in the normal and correct operation of the testmethod, exceed the following value in only one case in twenty:Determinability 5 0.59=m (3)where:m = the mean of the two determinations12.1.2 Repeatability
46、 The difference between successiveresults (each the mean of a pair of determinations) obtained bythe same operator with the same apparatus under constantoperating conditions on identical material, would in the longrun, in the normal and correct operation of the test method,exceed the following value
47、 in only one case in twenty:Repeatability 5 0.42=m (4)where:m = is the mean of the two results12.1.3 ReproducibilityThe difference between two inde-pendent results (each the mean of a pair of determinations)obtained by different operators working in different laborato-ries would, in the long run, ex
48、ceed the following value onlyone case in twenty:Reproducibility 5 0.71=m (5)where:m = the mean of the two test results.12.2 BiasThe procedure in this test method has no biasbecause the value of oxidation induction time can be definedonly in terms of a test method.13. Keywords13.1 differential scanni
49、ng calorimetry; lubricating grease;OIT; onset temperature; oxidation; oxidation coefficient; oxi-dation induction time; PDSC; thermal analysis6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1314.FIG. 4 Typical PDSC Thermal CurveD5483 05 (2015)4APPENDIX(Nonmandatory Information)X1. PDSC ROUND ROBIN DATAX1.1 See Table X1.1 for PDSC Round Robin data.ASTM International takes no position respecting the validity of any patent rights asserted in connecti
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