1、Designation: E 1559 03Standard Test Method forContamination Outgassing Characteristics of SpacecraftMaterials1This standard is issued under the fixed designation E 1559; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast revision. 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 covers a technique for generating datato characterize the kinetics of the release of outgassingproduc
3、ts from materials. This technique will determine boththe total mass flux evolved by a material when exposed to avacuum environment and the deposition of this flux on surfacesheld at various specified temperatures.1.2 This test method describes the test apparatus and relatedoperating procedures for e
4、valuating the total mass flux that isevolved from a material being subjected to temperatures thatare between 298 and 398K. Pressures external to the sampleeffusion cell are less than 7 3 103Pa (5 3 105torr).Deposition rates are measured during material outgassing tests.A test procedure for collectin
5、g data and a test method forprocessing and presenting the collected data are included.1.3 This test method can be used to produce the datanecessary to support mathematical models used for the predic-tion of molecular contaminant generation, migration, anddeposition.1.4 All types of organic, polymeri
6、c, and inorganic materialscan be tested. These include polymer potting compounds,foams, elastomers, films, tapes, insulations, shrink tubing,adhesives, coatings, fabrics, tie cords, and lubricants.1.5 There are two test methods in this standard. Test MethodA uses standardized specimen and collector
7、temperatures. TestMethod B allows the flexibility of user-specified specimen andcollector temperatures, material and test geometry, and user-specified QCMs.1.6 The values stated in SI units are to be regarded as thestandard.1.7 This standard does not purport to address all of thesafety concerns, if
8、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:E 177 Practice for Use of the Terms Precision and
9、 Bias inASTM Test Methods2E 595 Test Method for Total Mass Loss and CollectedVolatile Condensable Materials from Outgassing in aVacuum Environment3IEEE/ASTM SI 10 American National Standard for Use ofthe International System of Units (SI): The Modern MetricSystem22.2 Military Standard:MIL-P-27401C P
10、ropellant Pressurizing Agent, Nitrogen43. Terminology3.1 Definitions:3.1.1 AT cut crystal, na quartz crystal orientation thatminimizes the temperature coefficient (frequency change ver-sus temperature) over a wide range of temperature.3.1.2 collected volatile condensable material, CVCM,n(from Test M
11、ethod E 595). The quantity of outgassedmatter from a test specimen that condenses on a collectormaintained at a specific constant temperature for a specifiedtime and measured before and after the test outside thechamber.3.1.2.1 DiscussionCVCM is specific to Test MethodE 595 and is calculated from th
12、e condensate mass determinedfrom the difference in mass of the collector plate before andafter the test in a controlled laboratory environment. CVCM isexpressed as a percentage of the initial specimen mass. Theview factor is not considered; so all the VCM outgassing fromthe sample may not be collect
13、ed. Care should be used incomparing the CVCM from Test Method E 595 with VCMfrom this test method.3.1.3 differential scanning calorimetry, DSC, na tech-nique in which the difference in energy inputs into a substance1This test method is under the jurisdiction of ASTM Committee E21 on SpaceSimulation
14、and Applications of Space Technology and is the direct responsibility ofSubcommittee E21.05 on Contamination.Current edition approved May 10, 2003. Published June 2003. Originallyapproved in 1993. Last previous edition approved in 2000 as E 1559 00.2Annual Book of ASTM Standards, Vol 14.02.3Annual B
15、ook of ASTM Standards, Vol 15.03.4Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.and a reference mater
16、ial is measured as a function of tempera-ture while the substance and reference material are subjected toa controlled-temperature program.3.1.4 effusion cell, na container, placed in a vacuum, inwhich a sample of material can be placed and heated to somespecified temperature.3.1.4.1 DiscussionThe co
17、ntainer has a cylindrical orificeat one end so that evolving gases exit the cell in a controlledmanner. The effusion cell dimensions and orifice size arespecified such that there is free molecular flow of the evolvinggasses and a predictable molecular flux from the orifice.3.1.5 mass flux, nthe mass
18、 of molecular flux.3.1.6 molecular flux (moleculescm2s1), nthe numberof gas molecules crossing a specified plane in unit time per unitarea.3.1.7 nonvolatile residue, NVR, nthe quantity of residualmolecular and particulate matter remaining following thefiltration of a solvent containing contaminants
19、and evaporationof the solvent at a specified temperature.3.1.8 outgassing, nthe evolution of gas from a material,usually in a vacuum. Outgassing also occurs in a higherpressure environment.3.1.9 quartz crystal microbalance, QCM, na device formeasuring small quantities of mass using the properties of
20、 aquartz crystal oscillator.3.1.9.1 DiscussionThe resonant frequency of a quartzcrystal oscillator is inversely proportional to the thickness ofthe crystal. When the mass of a uniform deposit is smallrelative to the mass of the crystal, the change in frequency isproportional to the mass of the depos
21、it.3.1.10 QCM thermogravimetric analysis, QTGA, na tech-nique in which a QCM is heated at a constant rate to removea collected deposit.3.1.10.1 DiscussionThis is performed to determine theevaporation characteristics of the species in the deposit. Themass of the deposit on the QCM is recorded as a fu
22、nction oftime or temperature.3.1.11 residual gas analyzer, RGA, na mass spectrometermounted inside or attached to a vacuum chamber.3.1.11.1 DiscussionRGA can be used for identifyinggases in the vacuum chamber.3.1.12 total mass flux (gcm2s1), nthe summation of themass from all molecular species cross
23、ing a specified plane inunit time per unit area.3.1.13 total mass loss, TML, ntotal mass of materialoutgassed from a test specimen that is maintained at a specifiedconstant temperature and operating pressure for a specifiedtime and measured within the test chamber. TML is expressedas a percentage of
24、 the initial specimen mass. In addition, TMLcan be normalized with respect to the sample surface area andbe expresed as g/cm2.3.1.13.1 in-situ TML, ncalculated from the mass depos-ited on a cryogenically cooled QCM and the view factor fromthe effusion cell orifice to the QCM.3.1.13.2 DiscussionIn-si
25、tu TML is a function of theoutgassing test time and is expressed as a percentage of theinitial specimen mass. This is not necessarily the same as theTML determined by Test Method E 595.3.1.13.3 ex-situ TML, ntotal mass of material outgassedfrom a test specimen that is maintained at a specified const
26、anttemperature and operating pressure for a specified time andmeasured outside the test chamber.3.1.13.4 DiscussionEx-situ TML is calculated from themass of the specimen as measured before and after the test ina controlled laboratory environment and is expressed as apercentage of the initial specime
27、n mass. (From Test MethodE 595.)3.1.14 total outgassing rate, nthe net rate of mass lossfrom a material sample as a result of outgassing. Totaloutgassing rate can be normalized per unit sample surface areaand expressed as gcm2s1or it can be normalized per unitinitial sample mass and expressed as gg1
28、s1.3.1.15 volatile condensable material, VCM, nthe matterthat outgasses from a material and condenses on a collectorsurface that is at a specified temperature.3.1.15.1 DiscussionFor this test method, this is the quan-tity of outgassed matter from a test specimen that condenses onsurfaces maintained
29、at QT2 or QT3. The VCM is calculatedfrom the mass deposited on QCM2 or QCM3 and the viewfactor from the effusion cell orifice to the QCMs. VCM is afunction of the outgassing test time and is expressed as apercentage of the initial specimen mass. In addition, VCM canbe normalized with respect to the
30、sample surface area and beexpressed as g/cm2. This is not the same as CVCM asdetermined by Test Method E 595 (see 3.1.2).3.2 Acronyms:Acronyms:3.2.1 GN2, ngaseous nitrogen.3.2.2 LN2, nliquid nitrogen.3.2.3 MAPTIS, nMaterials and Process Technical Infor-mation Service.3.3 Definitions of Terms Specifi
31、c to This Standard:3.3.1 QCM1the QCM that is operating at the temperatureTQ1 (cryogenic) for measuring the total outgassing rate.3.3.2 QCM2 and QCM3the QCMs that are operating attemperatures TQ2 and TQ3 for the measurement of thedeposition of outgassing matter.4. Summary of Test Method4.1 The test a
32、pparatus described in this test method isdesigned to measure outgassing rate data that can be used todevelop kinetic expressions for use in models that predict theevolution of molecular contaminants and the migration anddeposition of these contaminants on spacecraft surfaces. Ma-terials that contain
33、 volatile species that will be outgassed underthe temperature and vacuum conditions of this test method canbe characterized. The quartz crystal microbalances used in thistest method provide a sensitive technique for measuring verysmall quantities of deposited mass. In addition to providingdata for k
34、inetic expressions, the reduced data can be used tocompare the outgassing behavior of different materials formaterial selection purposes.4.2 There are two test methods in this standard. Test MethodAis the standard procedure using prescribed configurations andtemperatures. Test Method B allows for th
35、e use of spacecraftsystem specific temperatures, configurations, and QCM collec-tor surface finishes.E15590324.3 The measurements are made by placing the materialsample in an effusion cell so that the outgassing flux leavingthe cell orifice will impinge on three QCMs which are arrangedto view the or
36、ifice.Afourth QCM is optional. The effusion cellis held at a constant temperature in the high vacuum chamberand has a small orifice directed at the QCMs. The QCMs arecontrolled to selected temperatures. The total outgassing rate isdetermined from the collection rate on a cryocooled QCM. Atthe end of
37、 the isothermal test, the QCMs are heated in acontrolled manner to determine the evaporation characteristicsof the deposits.4.4 The effusion cell is loaded from the vacuum interlockchamber to the main test chamber and is positioned at a fixeddistance and angle with respect to the QCM surfaces. Theef
38、fusion cell is temperature controlled to provide constant anduniform heating of the sample. The vacuum interlock chamberis a device that enables the expedient introduction of the testsample into the high vacuum of the main test chamber. Use ofthe interlock chamber to load and unload samples prevents
39、 lossof vacuum in the main chamber and diminishes the need topump it down before each test.4.5 The QCM collection method for measuring the totaloutgassing rate from a sample is an indirect technique. Ratherthan directly measuring sample mass loss, the basic measure-ment is the fraction of the flux t
40、hat condenses on the cryogeni-cally cooled QCM collector at a point in the outgassing flowfield. That point in the flow field is defined as the geometriclocation of the QCM relative to the effusion cell orifice, whichis at a fixed location. To determine the rate of sample mass lossfrom the rate of Q
41、CM collection, the view factor from theQCM to the effusion cell orifice and the angular distribution offlux leaving the orifice must be determined. This relationshipcan be calculated from the apparatus geometry and the effusioncell orifice dimensions.4.6 AQCM thermogravimetric analysis (QTGA) test i
42、s alsoincluded in the procedure. This technique heats the QCMs at aconstant rate to measure evaporation characteristics of thedeposits collected on the QCMs. The QTGA also provides aneffective means to clean the QCM surfaces before subsequenttests.4.7 It is critical to the posttest analysis that the
43、 materialsample be completely described and specified, so that theoutgassing characteristics can be applied to the material whenused on a spacecraft. It is also necessary so that any materialsample can be properly compared with that of other samples.The outgassing rate of the material will, in gener
44、al, bedetermined by its composition, processing history, and envi-ronmental conditioning before the test.All test sample process-ing should be representative of normal material processing andusage. All materials are environmentally conditioned to speci-fied conditions. However, samples may be subjec
45、ted to envi-ronmental conditions that are expected during actual use. Testsample processing and conditioning history shall be included inthe test report.4.8 Because outgassing of all materials is, to some extent,diffusion rate controlled, the outgassing rate of a test sampledepends on the distance f
46、rom the sample interior to a freesurface. Hence, the geometry of a test sample must becontrolled in a specified manner to permit meaningful inter-pretation of the data. When possible, the sample geometryshould be in the specified configuration to simplify modeling.However, the material sample can be
47、 made with the samegeometry as it would have in an actual application.5. Test Apparatus5.1 DescriptionThe test apparatus consists of four mainsubsystems: a vacuum chamber, a temperature control system,internal configuration, and a data acquisition system. Fig. 1 isa schematic of the systems, and Fig
48、. 2 shows the vacuumchamber and internal configuration.5.2 Vacuum ChamberThe principal components of thevacuum chamber are the main test chamber, the vacuuminterlock chamber, and cryogenic shrouds (for example, LN2).A high-vacuum gate valve is used to isolate the main testchamber from the interlock
49、chamber. This allows the effusioncell to be withdrawn or inserted into the main chamber withoutthe loss of high vacuum in the main chamber. High-vacuumelectrical and mechanical feedthroughs are used to access theinterior of the chamber.5.3 Internal ConfigurationThree quartz crystal microbal-ances (QCMs) (a fourth QCM is optional), an effusion cell, andcryogenic heat sinks in the chamber are the principal compo-nents. The cryogenic heat sinks are used to ground the QCMsthermally and to cool shrouds which surround the effusion celland Q
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