1、Designation: D 7214 07aAn American National StandardStandard Test Method forDetermination of the Oxidation of Used Lubricants by FT-IRUsing Peak Area Increase Calculation1This standard is issued under the fixed designation D 7214; the number immediately following the designation indicates the year o
2、foriginal 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.INTRODUCTIONThis test method was jointly developed with “Groupement F
3、rancais de Coordination” (GFC),technical committee LM5 and “Coordinating European Council” (CEC) Surveillance Group T-048 forthe purpose of monitoring the oxidation stability of artificially aged automotive transmission fluids.This test method has been used in the CEC L-48-A-00 method as an end of t
4、est measurementparameter.1. Scope*1.1 This test method covers the determination of the oxida-tion of used lubricants by FT-IR (Fourier Transform InfraredSpectroscopy). It measures the concentration change of con-stituents containing a carbonyl function that have formedduring the oxidation of the lub
5、ricant.1.2 This test method may be used to indicate relativechanges that occur in an oil under oxidizing conditions. Thetest method is not intended to measure an absolute oxidationproperty that can be used to predict performance of an oil inservice.1.3 This test method was developed for transmission
6、 oilswhich have been degraded either in service, or in a laboratorytest, for example a bulk oxidation test. It may be used for otherin-service oils, but the stated precision may not apply.1.4 The results of this test method may be affected by thepresence of other components with an absorbance band i
7、n thezone of 16001800 cm-1. Low PAI values may be difficult todetermine in those cases. Section 6 describes these possibleinterferences in more detail.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does no
8、t 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 ASTM Standard
9、s:2D 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD 6299 Practice for Applying Statistical Quality AssuranceTechniques to Evaluate Analytical Measurement SystemPerformanceE 131 Terminology Relating to Mol
10、ecular SpectroscopyE 1421 Practice for Describing and Measuring Performanceof Fourier Transform Mid-Infrared (FT-MIR) Spectrom-eters: Level Zero and Level One TestsE 1866 Guide for Establishing Spectrophotometer Perfor-mance Tests2.2 CEC Standard:CEC L-48-A-00 Oxidation Stability of Lubricating Oils
11、Used in Automotive Transmissions by Artificial Aging33. Terminology3.1 DefinitionsFor terminology relating to molecularspectroscopic methods, refer to Terminology E 131.3.2 Definitions of Terms Specific to This Standard:1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Pr
12、oducts and Lubricants and is the direct responsibility of SubcommitteeD02.96 on In-Service Lubricant Testing and Condition Monitoring Services.Current edition approved Dec. 1, 2007. Published January 2008. Originallyapproved in 2006. Last previous edition approved in 2007 as D 721407.2For referenced
13、 ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Coordinating European Council (CEC), c/o Interlynk Admin-ist
14、rative Services, Ltd., P.O. Box 6475, Earl Shilton, Leicester, LE9 9ZB, U.K.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Copyright by ASTM Intl (all rights reserved
15、); Fri May 23 03:48:11 EDT 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.3.2.1 carbonyl region, nregion of the FT-IR spectrumcorresponding to the absorbance of compounds containing acarbonyl function. Depending on the nature of the carbo
16、nylcompounds, this region is usually located between approxi-mately 1820 cm-1and 1650 cm-1.3.2.2 differential spectrum, nFT-IR absorbance spectrumresulting from the subtraction of the fresh oil from the used oil.3.2.3 PAI (peak area increase), narea of the carbonylregion of the differential FT-IR sp
17、ectrum, divided by the cellpathlength in millimetres. In this standard, PAI refers to arelative measurement of the oxidation of a used lubricant byFT-IR.4. Summary of Test Method4.1 FT-IR spectra of the fresh oil and of the used oil arerecorded in a transmission cell of known pathlength. Bothspectra
18、 are converted to absorbance and then subtracted. Usingthis resulting differential spectrum, a baseline is set under thepeak corresponding to the carbonyl region around 1650 cm-1and 1820 cm-1and the area created by this baseline and thecarbonyl peak is calculated. The area of the carbonyl region isd
19、ivided by the cell pathlength in millimetres and this result isreported as Peak Area Increase (PAI).5. Significance and Use5.1 The PAI is representative of the quantity of all thecompounds containing a carbonyl function that have formed bythe oxidation of the lubricant (aldehydes, ketones, carboxyli
20、cacids, esters, anhydrides, etc.). The PAI gives representativeinformation on the chemical degradation of the lubricant whichhas been caused by oxidation.5.2 This test method was developed for transmission oilsand is used in the CEC L-48-A-00 test (Oxidation Stability ofLubricating Oils Used in Auto
21、motive Transmissions by Artifi-cial Aging) as a parameter for the end of test evaluation.6. Interferences6.1 Some specific cases (very viscous oil, use of ester asbase stock, high soot content) may require a dilution of thesample and a specific area calculation, which are described in14.1-14.3. In t
22、hose cases, the result is corrected by a dilutionfactor, which is applied to the sample.7. Apparatus7.1 FT-IR Spectrophotometer, suitable for recording mea-surements between 1650 cm-1and 1820 cm-1and with aresolution of 4 cm-1.7.2 Transmission Cell, with windows of potassium bromide,having a known p
23、athlength of approximately 0.025 to 0.1 mm.7.3 Syringe, or Other Automated or Semi-Automated De-vice, with adequate volume to fill the cell, for example, 2 mL.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended
24、thatall reagents shall conform to the specifications of the commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available. Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without l
25、essening theaccuracy of the determination.8.2 Heptane, used as cleaning solvent. Other solvents andsolvent mixtures may be used provided they adequately cleanthe cell(s) between samples. A 50/50 mixture of cyclohexaneand toluene has been found to be useful in cleaning cells afterhighly contaminated
26、and degraded samples have been run.(WarningFlammable.)8.3 PAO4, used as dilution oil (PAO4: PolyAlphaOlefinwith a kinematic viscosity at 100C of approximately 4 mm2/s)9. Calibration and Standardization9.1 Calculation of the Cell PathlengthUse a cell with aknown pathlength of approximately 0.025 to 0
27、.1 mm. Calibratethe infrared cell pathlength using the interference fringemethod:9.1.1 Acquire the single beam background infrared spec-trum. Using the empty infrared cell in the infrared spectrometersample compartment, acquire the cell single beam infraredspectrum. Calculate the transmittance spect
28、rum by dividing thecell single beam spectrum by the background single beamspectrum. Optionally, convert the transmittance spectrum to anabsorbance spectrum by taking the negative logarithm (base10) of the transmittance spectrum. The fringe calculation maybe done on either the transmittance or absorb
29、ance. spectrum.The final spectrum is obtained by subtraction of the back-ground spectrum from the cell spectrum.NOTE 1This computation is generally an integral part of the infraredspectrometer software.9.1.2 Choose 2 minima separated by about 20 measurableinterference fringes as shown in Fig. 1. Cou
30、nt the number ofinterference fringes between the lower and the higher wave-numbers, referred to as l1and l2.NOTE 2The spectral range may be chosen freely in an area where thefringes are regular.9.1.3 The cell pathlength is calculated by the formula:e 55nl12l2!(1)where:e = the pathlength in mm, andn
31、= the number of fringes between l1and l2.9.2 Instrument Performance Checks:9.2.1 Periodically, the performance of the FT-IR instrumentshould be monitored using the Level 0 procedure of PracticeE 1421. If significant change in performance is noted, thentesting should be suspended until the cause of t
32、he performancechange is diagnosed and corrected.9.2.2 Alternative instrument performance tests conformingto the recommendations of Guide E 1866 may be substitutedfor the Practice E 1421 test.10. Conditioning10.1 Before using the infrared cell ensure that it is clean bywashing through with a suitable
33、 solvent, for example, heptane.Dry the cell using dry air or nitrogen, if necessary. Calibratethis cell as described in Section 9.D 7214 07a2Copyright by ASTM Intl (all rights reserved); Fri May 23 03:48:11 EDT 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further repro
34、ductions authorized.11. Preparation of Sample of Used Oil11.1 Refer to Practice D 4057 (Manual Sampling) or Prac-tice D 4177 (Automatic Sampling) for proper sampling tech-niques.11.2 When sampling used lubricants, the specimen shall berepresentative of the system sampled and shall be free ofcontamin
35、ation from external sources. As used oil can changeappreciably in storage, test samples as soon as possible afterremoval from the lubricating system and note the dates ofsampling and testing.11.3 If the sample of used oil contains visible sediment, heatto 60 6 5C in the original container and agitat
36、e until all of thesediment is homogeneously suspended in the oil. If the originalcontainer is a can or if it is glass and more than three-fourthsfull, transfer the entire sample to a clear-glass bottle having acapacity at least one third greater than the volume of thesample. Transfer all traces of s
37、ediment from the originalcontainer to the bottle by vigorous agitation of portions of thesample in the original container.12. Procedure12.1 Acquire a single beam background spectrum. Thisbackground spectrum may be used in the conversion of allsubsequent spectra for at least one day.12.2 With a syrin
38、ge or other injection device, fill the cellwith the fresh oil, and record its single beam sample spectrum.Convert this spectrum to a transmittance spectrum by dividingit by the single beam background spectrum and to a fresh oilabsorbance spectrum by taking the negative logarithm (base10) of the tran
39、smittance spectrum. Accumulate an adequatenumber of scans for a satisfactory noise level of 2 mAbs2000 cm-1.NOTE 3Assuming there are no absorbance peaks in the range from2050 to 1950 cm-1for the sample, the noise level may be estimated as thestandard deviation of the absorbance data over this spectr
40、al range.12.3 Empty and clean the cell. Heptane may be used. Fillthe cell with the aged oil, and record its single beam samplespectrum. Convert this spectrum to a transmittance spectrumby dividing by the single beam background spectrum, and to anaged oil absorbance spectrum by taking the negative lo
41、garithm(base 10) of the transmittance spectrum.NOTE 4It may happen that the aged oil is too viscous to fill the cell.Then it is possible to proceed to a dilution as described in 12.4.1.12.4 Generate a differential spectrum by subtracting thefresh oil absorbance spectrum from the aged oil absorbances
42、pectrum (see Fig. 2). Locate and zoom on the carbonyl regioncentered at 1720 cm-1. Processing may continue if the maxi-mum absorbance of this carbonyl region is lower than 1.5.NOTE 5Since the carbonyl region absorption minima (close to 1820cm-1and 1650 cm-1) can vary with the type of oil sample bein
43、g tested, itwas decided not to use fixed baseline limits for calculating the area A.NOTE 6The carbonyl band may consist of more than one peakmaxima.NOTE 7Do not calculate the differential peak area by difference of thepeak area of the aged oil with the peak area of the fresh oil.FIG. 1 Example of In
44、terference Fringes for Cell Pathlength CalculationD 7214 07a3Copyright by ASTM Intl (all rights reserved); Fri May 23 03:48:11 EDT 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.12.4.1 If the maximum absorbance of the carbonyl region ofth
45、e differential spectrum is higher than 1.5: dilute with 1 %accuracy by weight both fresh and aged oils with the samedilution factor, D (PAO 4 is recommended as dilution oil). Forexample,D=2fora50%(1:1) wt/wt dilution. Record the twospectra, convert them to absorbance and subtract them. If themaximum
46、 absorbance of the carbonyl region is still higher than1.5, then use a higher dilution factor. This occurrence couldhappen in the case of ester or soot-containing oils.NOTE 8The cell pathlength may be changed to 0.05 mm or 0.025 mmif absorbance in the assessment area is greater than 1.5.NOTE 9Diluti
47、on factors are commonly chosen between 2 and 10.12.4.2 If the maximum absorbance of the carbonyl region ofthe differential spectrum is lower than 1.5: draw a base lineconnecting the absorption minima located at each side of thisregion as shown on the spectrum in Fig. 2. These minima areusually close
48、 to 1820 cm-1and 1650 cm-1within 6 20 cm-1.Calculate and record the differential peak area as area A. (Thismay be done automatically with the spectrometer software.)13. Calculation of Results13.1 The results are reported as PAI (peak area increase):carbonyl region area, A multiplied by the dilution
49、factor, D anddivided by the cell pathlength, e in mm:PAI 5area Ae mm!3 D (2)13.1.1 If no dilution was needed, the dilution factor, D is 1.14. Procedures for Interferences14.1 The results of this test method may be affected by thepresence of other components with an absorbance band in thezone of 16001800 cm-1. Low PAI values may be difficult todetermine in those cases. The following procedures may beused if interferences are present.14.2 Soot-Containing OilsThe presence of soot degradesthe spectra by decreasing the transmittance level. This casemay require
