1、Designation: D 6186 98 (Reapproved 2003)e1An American National StandardStandard Test Method forOxidation Induction Time of Lubricating Oils by PressureDifferential Scanning Calorimetry (PDSC)1This standard is issued under the fixed designation D 6186; the number immediately following the designation
2、 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.e1NOTEWarning notes were editorially moved into
3、the standard text in August 2003.1. Scope1.1 This test method covers the determination of oxidationinduction time of lubricating oils subjected to oxygen at 3.5MPa (500 psig) and temperatures between 130 and 210C.1.2 The values stated in SI units are to be regarded as thestandard.1.3 This standard d
4、oes 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. Terminology2.1 Definitions of T
5、erms Specific to This Standard:2.1.1 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.2.1.2 oxidation induction time, (OIT), na period of timeduring which the oxi
6、dation rate accelerates from zero to amaximum and which corresponds to the extrapolated onsettime.2.1.3 thermal curve, na graph of sample heat flow versustime.3. Summary of Test Method3.1 A small quantity of oil is weighed into a sample pan andplaced in a test cell. The cell is heated to a specified
7、temperature and then pressurized with oxygen. The cell is heldat a regulated temperature and pressure until an exothermicreaction occurs. The extrapolated onset time is measured andreported as the oxidation induction time for the lubricating oilat the specified test temperature.4. Significance and U
8、se4.1 Oxidation induction time, as determined under theconditions of this test method, may be used as an indication ofoxidation stability.2This test method is faster than other oiloxidation tests and requires a very small amount of sample. Itmay be used for research and development, quality control,
9、 andspecification purposes. However, no correlation has beenestablished between the results of this test method and serviceperformance.5. Apparatus5.1 Pressure Differential Scanning Calorimeter (PDSC),equipped with the following items:5.1.1 Sample Enclosure, with capability to 3.5 6 0.2 MPa(500 6 25
10、 psig) at 210C and pressure gage graduated atintervals of 200 KPa (28.6 psig) or less.5.1.2 Thermal Analyzer.5.1.3 Aluminum Solid Fat Index (SFI) Sample PanSeeNote 1.5.1.4 Oxidation Stability Software.5.1.5 Calibration Software.5.1.6 Calibrated Flowmeter, with a capacity of at least 200mL/min and gr
11、aduated in intervals of 5 mL or less.5.1.7 Sample Encapsulation Press.NOTE 1It has been found that when oil samples are prepared with SFIpans which have more consistent surface areas than standard flat bottompans, reproducibility is improved.NOTE 2Stainless steel or copper tubing is compatible with
12、oxygen.NOTE 3See Fig. 1 for a diagram of a typical test unit.6. Reagents and Materials6.1 Oxygen, a minimum purity of 99.5 % oxygen by vol-ume. (WarningOxidizer. Gas under pressure.)6.2 Indium, of not less than 99.9 % indium by mass.1This test method is under the jurisdiction of ASTM Committee D02 o
13、nPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.09 on Oxidation.Current edition approved May 10, 2003. Published August 2003. Originallyapproved in 1997. Last previous edition approved in 1998 as D 618698.2Rhee, In-Sik, “Development of New Oxidation Stability T
14、est Method forLubricating Oils Using a Pressure Differential Scanning Calorimeter (PDSC),”NLGI Spokesman, Vol 65, No. 3, June 2001, pp. 1623.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Calibration7.1 Sample Temperature Calibra
15、tion:7.1.1 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 crimped pan onto the sampleplatform in the pressure cell. Seal an empty pan in the samemanner and place it on the reference platform. Set the
16、 cellcover in place and close the cell.7.1.2 Open the oxygen cylinder valve slightly and set apressure of 3.5 6 0.2 MPa (500 6 25 psig) on the cell inlet linewith the pressure regulator. Partially open the inlet valve on thecell and allow the pressure to slowly build up in the cell. Thisrequires app
17、roximately 2 min. Using the outlet valve, adjustand maintain the oxygen purge rate through the flowmeter at100 6 10 mL/min.7.1.3 Set the thermal analyzer to heat from ambient tem-perature (approximately 22C) to 180C at a programmed rateof 10C/min. After completion of the run measure the meltingtempe
18、rature of the indium. If the melting temperature differsfrom 157.4 6 0.2C (see Note 4) correct the difference byusing either the hardware or software calibration proceduredescribed in the manufacturers instruction manual. If thehardware calibration procedure is used, perform the tempera-ture correct
19、ion under 3.5 MPa (500 psig) oxygen pressure witha 100 mL/min purge rate. A typical melting calibration curve isshown in Fig. 2.NOTE 4The melting temperature of indium is 156.6C at atmosphericpressure, but has been found to be elevated to 157.4C under theconditions of this test method, 3.5 MPa (500
20、psig) of oxygen.37.2 Temperature Controller Calibration:7.2.1 Remove both the sample pan and the reference panfrom the cell, then close the cell. Slowly pressurize the cellwith 3.5 6 0.2 MPa (500 6 25 psig) oxygen and adjust thepurge rate to 100 6 10 mL/min using the cell outlet valve.Select the des
21、ired test temperature (either 210, 180, 155, or130C).7.2.2 Program the cell to maintain the selected test tempera-ture. If, after 10 min, the displayed cell temperature differs bymore than 6 0.2C from the selected temperature, slowlyadjust the temperature controller until they agree. After makingan
22、adjustment, wait at least 5 min to make certain that thetemperature is stable before continuing. If the PDSC equip-ment does not have this function, the control calibration shallbe followed according to the equipment manufacturers rec-ommendations.7.3 Cell Base Pressure Gage CalibrationConduct theca
23、libration using a calibrated pressure transducer or a previ-ously calibrated gage according to the pressure cell manufac-turers instructions.8. Procedure8.1 Before starting a test, the control thermocouple calibra-tion shall be conducted at the test temperature (either 210, 180,155, or 130C) accordi
24、ng to 7.2.1 and 7.2.2. When the testtemperature is not known, conduct the calibration at 210C.8.2 Weigh 3.0 6 0.2 mg of oil into a new sample pan.Spread the sample evenly upon the flat portion. Do not spillany of the sample into the trough portion of the pan. A flatbottom pan can be used if the samp
25、le is placed upon a 0.5 cmdiameter circle in the center of the pan.8.3 Place the uncovered pan containing the sample onto theplatform of the cell according to the PDSC manufacturersinstructions for placing the sample pan. Place a new empty panof the same configuration onto the cell platform accordin
26、g tothe PDSC manufacturers instructions for placing the referencepan. Close the cell and the pressure release valve.8.4 Beginning at ambient temperature (approximately22C), program the sample temperature to increase at a rate of100C/min to the test temperature.8.5 Allow the sample to equilibrate at
27、the test temperaturefor 2 min.8.6 Open the oxygen valve and slowly pressurize the cell to3.5 6 0.2 MPa (500 6 25 psig). This requires approximately2 min to reach maximum pressure. Measure the oxidationinduction time from the time when the oxygen valve is opened.8.7 As soon as the pressure has equili
28、brated, check the cellpurge rate and adjust and maintain at 100 6 10 mL/min withthe outlet valve.8.8 After a duration of 120 min from the time when theoxygen valve was opened, close the oxygen valve and slowlyrelease the cell pressure by opening the cell pressure release3Supporting data have been fi
29、led at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1007.FIG. 1 PDSC Test UnitFIG. 2 Calibration Curve for PDSCD 6186 98 (2003)e12valve. In the case of a sample for which the approximateoxidation induction time is known, the test can be stopped afterthe oxi
30、dation exotherm has occurred.8.9 Plot the thermal curve and measure the extrapolatedonset time for the oxidation exotherm. Report this time, to thenearest 1 min, as the oxidation induction time for the sample.If more than one oxidation exotherm is observed, report theoxidation induction time for the
31、 largest exotherm.NOTE 5A typical thermal curve is shown in Fig. 3.8.10 If the induction time is less than 10 min, rerun the testat the next lower temperature, starting at 8.2. Allow the cell tocool to ambient temperature before running the test at the nextlower temperature.9. Report9.1 Report, to t
32、he nearest minute, the oxidation inductiontime (OIT) for the sample.9.2 Report the test temperature.10. Precision and Bias10.1 PrecisionThe precision of this test method wasdetermined in accordance with currently accepted guidelines inCommittee D02s “Manual on Determining Precision Data forASTM Meth
33、ods on Petroleum Products and Lubricants.” Eightlaboratories evaluated thirteen samples at four different testtemperatures (130, 155, 180, and 210C) in the round robin andreported oxidation induction times ranged from 10 to 119 min.Appendix X2 lists round robin data and PDSC equipment usedby coopera
34、tors.10.1.1 RepeatabilityThe difference between successivetest results, obtained by the same operator with the sameapparatus under constant operating conditions on identical testmaterial, would in the long run, in the normal and correctoperation of the test method, exceed the following values onlyon
35、e case in twenty:r 5 0.17 m (1)wherem = average of the two test results.10.1.2 ReproducibilityThe difference between two singleand independent results obtained by different operators work-ing in different laboratories on identical test material, would inthe long run, in normal and correct operation
36、of the testmethod, exceed the following values only one case in twenty:R 5 0.35 m (2)where:m = average of the two test results.10.2 BiasThe procedure in this test method has no biasbecause the value of oxidation induction time can be definedonly in terms of a test method.11. Keywords11.1 differentia
37、l scanning calorimetry; lubricating oil; OIT;onset temperature; oxidation; oxidation coefficient; oxidationinduction time; PDSC; thermal analysisAPPENDIXES(Nonmandatory Information)X1. CALCULATION OF INDUCTION TIMESX1.1 The following kinetic equation can be used to predictinduction times of lubricat
38、ing oils at various test temperatures:t 5 A 3 e12 000/T(X1.1)A 5 OIT 3 e12 000/test temperature, Kwhere:t = calculated oxidation induction time, min.,A = oxidation coefficient of the oil, andT = temperature, K (for desired temperature).OIT = oxidation induction time at test temperature, min.FIG. 3 A
39、 Typical Thermal Curve From PDSC TestD 6186 98 (2003)e13X2. PDSC ROUND ROBIN DATATABLE X2.1 Round Robin Cooperators and PDSC InstrumentsLAB Instrument Sample pan1 TA 2200 and 961 SFI2 TA 2100 and 961 SFI3 TA 2100 and 961 SFI4 TA 961 SFI5 TA 912 (dural sample cell) SFI6 Mettler DSC 27HP Mettler sampl
40、e pan7 Mettler DSC Mettler sample pan8 thermal science thermal science panTABLE X2.2 PDSC Round Robin DataLAB D-11 D-12 D-13 D-14 D-15 D-16 D-17 D-18 D-19 D-20 D-21 D-22 D-231 42.6 52.7 44.3 86.6 77.9 36.7 26.8 15.8 20.5 118 85.1 29.7 33.940.8 46.9 45.7 77.5 85.1 38.6 26.3 15.4 19.6 116 79.9 29.1 35
41、.62 42.2 65.0 51.5 92.1 56.9 37.8 27.0 14.1 10.2 111 88.8 27.2 28.241.5 60.5 53.9 87.6 60.2 41.4 25.3 16.6 10.1 116 94.7 26.1 30.33 37.4 48.7 39.0 105 90.7 39.8 26.5 16.8 18.9 112 79.0 24.1 32.640.1 52.0 41.0 102 86.2 41.6 26.3 16.7 17.5 109 79.9 21.6 28.04 44.0 55.8 47.4 97.4 69.6 38.7 23.6 17.9 15
42、.2 109 75.6 26.8 34.343.4 45.7 46.0 88.8 67.9 34.0 22.5 13.9 13.2 105 68.1 28.8 34.25 37.0 53.0 41.6 84.6 63.8 38.9 30.1 14.0 14.6 95.8 79.2 26.9 26.136.1 52.2 39.4 85.3 62.9 40.0 31.3 15.6 13.6 96.9 79.0 28.4 26.26 38.8 47.0 39.3 122 57.9 23.3 31.4 18.1 17.9 100 103 32.7 37.238.6 51.8 39.4 121 56.6
43、 27.7 33.6 16.8 17.4 102 103 30.1 38.87 41.7 55.9 42.1 92.3 76.7 30.3 28.7 19.8 13.8 117 94.6 25.0 31.641.4 59.5 41.9 97.7 81.9 34.8 22.2 16.6 13.6 116 93.5 20.1 33.08 38.4 52.4 46.5 81.5 47.5 33.9 26.1 14.5 18.2 118 83.9 25.6 25.837.8 47.4 44.1 77.2 49.9 35.8 26.5 16.6 20.2 119 79.4 26.0 26.9TestTe
44、mperature, C180 130 180 180 180 180 210 210 180 210 155 155 210TABLE X2.3 Round Robin SamplesSample Type of Oil DescriptionD-11 engine oil mineral oilD-12 vegetable based hydraulic fluid rapeseed oilD-13 heavy duty diesel oil mineral oilD-14 hydraulic fluid with Zn mineral oilD-15 hydraulic fluid wi
45、thout Zn mineral oilD-16 turbine oil mineral oilD-17 gear oil mineral oilD-18 engine oil syntheticD-19 hydraulic fluid PAOD-20 aviation turbine oil polyol esterD-21 gear oil syntheticD-22 vegetable based hydraulic fluid sunflowerD-23 synthetic biodegradable oil polyol esterD 6186 98 (2003)e14ASTM In
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47、ly their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand s
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49、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).D 6186 98 (2003)e15
