ASTM_D_2715_-_92_2012.pdf

Designation:D271592(Reapproved 2012)Standard Test Method forVolatilization Rates of Lubricants in Vacuum1This standard is issued under the fixed designation D2715;the number immediately following the designation 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()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of the rates ofvolatilization of lubricants in a thermal-vacuum environment atpressures and temperatures necessary to obtain a measurablerate of evaporation,or evidence of decomposition.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard 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 ASTM Standards:2E296 Practice for Ionization Gage Application to SpaceSimulatorsE297 Methods for Calibrating Ionization Vacuum GageTubes33.Summary of Test Method3.1 A known quantity of specimen is placed in a thermalvacuum balance system and the evaporated material is con-densed on a cold plate.The weight of the specimen iscontinually recorded as a function of time for nominal constantsurface area.4.Significance and Use4.1 This test method provides data for comparison of theevaporation rate of lubricants used in unshielded bearings inthe space environment.5.Apparatus5.1 Recording Vacuum Microbalance,with capacity of 1 gor more,sensitivity of 0.01 mg or less,zero stability of 0.025mg or less for 8 h with ranges of weight change of 10 mg ormore,and 0.1 mg or less,capable of being pumped to 105Pa(107torr)or less.5.1.1 When Procedure B for the more volatile samples isused,the vacuum requirement shall be 102Pa(104torr)orless.5.2 Vacuum SystemA pumping system capable of main-taining a starting pressure of 106to 105Pa(108to 107torr)(5.1.1).An optically dense baffle system should be used toensure freedom from back-streaming.A conventional bell jarsystem with an oil diffusion pump,a mechanical back-uppump,and an optically dense,liquid,nitrogen-cooled baffle hasbeen found satisfactory on the configuration as shown in Fig.1.5.3 Furnace,with thermocouple indicator,capable of main-taining a constant sample temperature 63C.All parts of thisfurnace must be proved to be usable at the highest temperatureand vacuum contemplated.5.4 Recorder,capable of recording weight changes continu-ously with the balance used,to the performance specified in5.1.5.5 Specimen Container,made of 300 series stainless steelin the form of a straight cylinder with an aspect ratio of heightto diameter of approximately 1:14.Where chemical reactionsare experienced with the container,alternative materials maybe used.5.6 Contacting Thermocouple,touching solid or immersedin liquid specimens,with the leads brought out in such a wayas not to influence balance indication.5.7 Cold PlateA condensing shield cooled with liquidnitrogen to immobilize molecules evaporated from the lubri-cant which subtends,at least,a 160 arc from the center of thesample.5.8 Nude Ionization Gage,installed as described in PracticeE296 and calibrated as described in Methods E297.5.9 Optional Supplemental Equipment:5.9.1 Mass Spectrometer,to identify degassing products andevaporating species.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.L0.07 on Engineering Sciences of High Performance Fluids andSolids(Formally D02.1100).Current edition approved April 15,2012.Published April 2012.Originallyapproved in 1968.Last previous edition approved in 2007 as D271592(2007).DOI:10.1520/D2715-92R12.2For referenced 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.3Withdrawn.The last approved version of this historical standard is referencedon www.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.9.2 Infrared Optical Pyrometer System,for determiningthe specimen temperature.This must be calibrated against thethermocouple for each material used,due to emissivity effects.5.9.3 Copper Tab,on a cold plate facing the specimen,forX-ray analysis of the condensate.5.9.4 Noncontact Specimen Thermocouple,calibratedagainst 5.5.5.9.5 Pressure Recording Pen,added to the recorder.5.9.6 Time Derivative Computer,to report the rate directly.6.Reagents and Materials6.1 Antiwetting AgentA low-surface tension material forcoating the specimen container and the the