1、Designation: E1997 15Standard Practice for theSelection of Spacecraft Materials1This standard is issued under the fixed designation E1997; 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 paren
2、theses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 The purpose of this practice is to aid engineers,designers, quality and reliability control engineers, materialsspecialists, and systems designers in
3、the selection and controlof materials and processes for spacecraft, external portion ofmanned systems, or man-tended systems. Spacecraft systemsare very different from most other applications. Space environ-ments are very different from terrestrial environments and candramatically alter the performa
4、nce and survivability of manymaterials. Reliability, long life, and inability to repair defectivesystems (or high cost and difficultly of repairs for mannedapplications) are characteristic of space applications. Thispractice also is intended to identify materials processes orapplications that may re
5、sult in degraded or unsatisfactoryperformance of systems, subsystems, or components. Ex-amples of successful and unsuccessful materials selections anduses are given in the appendices.2. Referenced Documents2.1 ASTM Standards:2E595 Test Method for Total Mass Loss and Collected Vola-tile Condensable M
6、aterials from Outgassing in a VacuumEnvironmentG64 Classification of Resistance to Stress-Corrosion Crack-ing of Heat-Treatable Aluminum Alloys2.2 Marshall Space Flight Center (MSFC) Standard:MSFC-STD-3029 Guidelines to the Selection of MetallicMaterials for Stress Corrosion Cracking Resistance inSo
7、dium Chloride Environments32.3 Military Standards:4MIL-STD-889 Dissimilar MaterialsMIL-HDBK-5 Metallic Materials and Elements for Aero-space Vehicle StructuresMIL-HDBK-17 Properties of Composite Materials2.4 European Space Agency (ESA) Standard:PSS-07/QRM-0 Guidelines for Space Materials Selection52
8、.5 Federal Standard:QQ-A-250 Aluminum and Aluminum Alloy Plate andSheet, Federal Specification for43. Significance and Use3.1 This practice is a guideline for proper materials andprocess selection and application. The specific application ofthese guidelines must take into account contractualagreemen
9、ts, functional performance requirements for particu-lar programs and missions, and the actual environments andexposures anticipated for each material and the equipment inwhich the materials are used. Guidelines are not replacementsfor careful and informed engineering judgment and evaluationsand all
10、possible performance and design constraints andrequirements cannot be foreseen. This practice is limited tounmanned systems and unmanned or external portions ofmanned systems, such as the Space Station. Generally, it isapplicable to systems in low earth orbit, synchronous orbit, andinterplanetary mi
11、ssions.Although many of the suggestions andcautions are applicable to both unmanned and mannedspacecraft, manned systems have additional constraints andrequirements for crew safety which may not be addressedadequately in unmanned designs. Because of the added con-straints and concerns for human-rate
12、d systems, these systemsare not addressed in this practice.4. Design Constraints4.1 Orbital EnvironmentThe actual environment in whichthe equipment is expected to operate must be identified anddefined. The exposures and requirements for material perfor-mance differ for various missions. Environment
13、definitionincludes defining the range of temperature exposure, numberand rate of thermal cycles, extent of vacuum exposure, solarelectromagnetic radiation particulate radiation, (trapped by theearths magnetosphere, solar wind, solar flares, and gammarays) micrometeroids, launch loads and vibration,
14、structural1This practice is under the jurisdiction of ASTM Committee E21 on SpaceSimulation andApplications of Space Technology and is the direct responsibility ofSubcommittee E21.05 on Contamination.Current edition approved Oct. 1, 2015. Published November 2015. Originallyapproved in 1999. Last pre
15、vious edition approved in 2012 as E1997 12. DOI:10.1520/E1997-15.2For 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 webs
16、ite.3Marshall Space Flight Center, AL 35812, or .4Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.5European Space Agency, 810, Rue Mario-Nikis, 75738 Paris Cedex, France.Copyright ASTM I
17、nternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1loads, and so forth. Materials suitable for one orbit or missionenvironment may be unsuitable for others. The applicationsand requirements will define the suitability of the materials.4.2 Low Earth Orbi
18、t (Up to 100 km)Materials in thisregion could be exposed to trapped Van Allen belt (ionizing)radiation, solar ultraviolet radiation, corrosive attack by atomicoxygen (A.O.), and more frequent and more extreme thermalcycling and thermal shock as a result of frequent excursionsinto and out of the eart
19、hs shadow. Orbital impacts may be aproblem because of the large amount of debris in low orbits.Design life in orbit typically is on the order of 5 to 15 years.Inclination of the orbit affects the service environment, that is,polar orbits have a different flight profile than equatorial orbitsand have
20、 different profiles for radiation exposure.4.3 Synchronous Orbit (35 900 km)Materials in this re-gion are not exposed to significant atomic oxygen or very highenergy trapped radiation but may have more exposure tomedium energy ionizing electrons and protons, solar flares, andrelatively high levels o
21、f electromagnetic solar radiation(ultraviolet, VUV photons, and X-rays). The number of ther-mal cycles is less and may be over a narrower temperaturerange than low earth orbit. Meteoroids also should be consid-ered but are less likely to be significant compared to themanmade debris found in low orbi
22、ts. Design life in orbittypically is 5 to 15 years, with recent designs ranging from 10to 17 years.4.4 Interplanetary (Out-of-Earth Orbit)In addition to thethermal extremes and environments of synchronous orbit, inthe interplanetary environment, temperatures may be moreextreme, and micrometeoroids,
23、solar wind, and cosmic raysmay be critical. Ability to survive and remain functional formany years is important. Probes to the inner plants typicallyhave design lifetimes of 5 to 10 years. Those to the outerplanets and beyond may have design lifetimes of 15 to 30years.5. Materials to Avoid5.1 Certai
24、n materials are known to be undesirable andshould be avoided no matter what the mission. Others are ofconcern for certain missions or of more concern for somemissions than others. In general, it is recommended that oneavoid the materials described below:5.1.1 Metals with High Vapor Pressure in Vacuu
25、m andUnusual BehaviorsAvoid the use of metals such as mercury,cadmium, and zinc, either as plating or monolithic metals. It isimportant to exclude these metals both from the flight equip-ment and vacuum chambers. If these metals are used invacuum and heated even moderately, they will vacuum metal-li
26、ze both the cold walls of the chamber and any cold surfaceson equipment in the chamber. Also, pure tin has the curiousproperty of dendritic growth as a result of compressivestresses, or thermal or electrical gradients, forming whiskerswhich can cause shorts in electrical components or break offand b
27、ecome conductive contaminants. Some other metals suchas cadmium and zinc have similar whisker-growing properties,but not to the extent that tin has. Since they can also growwhiskers, they should not be used.5.1.2 Stress-Corrosion Sensitive MetalsMetals, which arestress-corrosion sensitive, should be
28、 avoided. Examples are2024 T6 and 7075 T6 Aluminum, which can be used if heattreated to conditions, such as 2024 T81 and 7075 T73, whichare not stress-corrosion sensitive. Many brasses and some steelalloys also are stress-corrosion sensitive; however, even alloys,which are stress-corrosion sensitive
29、 can be used if loaded incompression or if loaded to low sustained tensile stress levels,typically no more than 25 % of yield strength (see Classifica-tion G64 and MSFC-SPEC-522).5.1.3 Materials Forming Galvanic CouplesMaterialcombinations, which form galvanic couples greater than 0.5 evwhen exposed
30、 to a temperature and humidity controlledenvironment, such as during fabrication, testing, and storage,should be prohibited under most circumstances. Providingprotection from electrolytes and maintaining them in a con-trolled environment, such as during fabrication and testing,inhibits galvanic corr
31、osion. Some alloys, such as magnesium,magnesium lithium alloys, and gold, form a galvanic couplewith most common structural materials and must be protectedadequately to prevent creating galvanic couples which causethe anodic metal to corrode. Carbon composites are included inthe materials, which mus
32、t be evaluated for galvanic potential,since carbon forms galvanic couples with metals. If there is noelectrolyte present, galvanic couples greater than 0.5 ev arepermissible. Galvanic protection can be obtained by preventingelectrolyte from contacting the interfaces, interposing a dielec-tric materi
33、al, or adding a material that is compatible with eachof the other materials separately.5.1.4 Materials With Thermal or EnvironmentalLimitationsMaterials that are weak or brittle at the expectedservice temperature or environment should be avoided. Thesematerials included polymeric materials used at v
34、ery low orvery high temperatures and some metals used at low tempera-tures. In this context, “low” can be from -40 to -120C and“high” can be from 150 to 200C for polymers. Some materialsare readily attacked by certain chemicals or solutions. Forexample, aluminum alloys should not be used in strongly
35、 basicor acidic environments. Steels, particularly high carbon andferritic grades, are embrittled by halogens and hydrogen.Silicones are attacked by toluene. Titanium is attacked bymethanol.5.1.5 Materials Diffcult to Fabricate or TestMaterialsthat are difficult to fabricate, form, test, or inspect,
36、 or do nothave a history of consistency of properties or performance,should be avoided. Some materials, such as ceramics and mostrefractory metals, are relatively difficult to machine or form.Others are difficult to weld by conventional means. Somecannot be formed easily. Certain applications such a
37、s elevatedtemperature service may require use of ceramics or refractorymetals. That should not reduce the need for careful review andfunctional design of the equipment. All materials must be verycarefully evaluated to assure successful, economic fabricationand that the fabricated parts can be inspec
38、ted easily for hiddendefects.5.1.6 Materials That Have Excessive OutgassingIf thematerials have high collected volatile condensable materials(CVCM) or total mass loss (TML) when exposed at 125C andE1997 152tested, they generally are excluded from spacecraft applica-tions. Normal acceptance limits fo
39、r outgassing according toTest Method E595 are no higher than 1.0 %TMLand no higherthan 0.10 % CVCM. Some of these materials release conden-sates that react adversely with solar radiation or radiation andvacuum and may degrade sensitive surfaces. Others cancontaminate surfaces or equipment such that
40、functionality isimpaired. High mass loss can indicate a loss or properties andfunctionality in space. Sometimes, a material will have accept-able outgassing per normal requirements, but it may be in aparticularly sensitive location, or the outgassing product mayhave an adverse effect on specific sen
41、sitive equipment. Theseconditions can require establishing lower levels for acceptableoutgassing or may require analysis of outgassed componentsand evaluation of the acceptability for the specific application.NOTE 1The test is defined as performed at 125C unless clearly statedotherwise; therefore, a
42、cceptability is limited to exposures below 125C.The test temperature of 125C was assumed to be significantly above theexpected operating temperature in service. If expected operating tempera-tures exceed 85 to 90C the test temperature should be increased. It issuggested that the test temperature be
43、at least 30C higher than expectedmaximum service temperature in order to provide material comparisonsfor TML and CVCM.NOTE 2Metallic materials do not “outgas,” but some metals, such aszinc and cadmium, do exhibit high vapor pressure at relatively low(1000-pi design loads) re-quire specific training
44、to apply the adhesive, including surfacepreparation and process controls for consistency and effective,reliable strength.X2.2 General Usage PrecautionsUsage precautions mustbe observed to avoid undesirable or unacceptable results andeven system failures. The importance of thermal sensitivitymust not
45、 be overlooked. For example, the elastomeric seals,which failed and resulted in the loss of the Challenger, wereoperated at a temperature below their known limits. Epoxiesoften have brittle points in the 20 to 60C range. Epoxiesshould not be used in direct contact with ceramic parts, such asceramic-
46、cased diodes when usage temperatures are low. Aflexible intermediate material must be applied to prevent brittlefracture of the ceramic. Silicones are normally flexible attemperatures as low as 110C. Flexible silicones should beused rather than epoxies to bond ceramics for low temperatureapplication
47、s directly (see 5.1.14). Urethanes tend to becomebrittle at temperatures of approximately 20 to 40C andshould be used with great care or avoided at lower tempera-tures. High temperatures result in significant loss in bondstrength for adhesives. Few adhesives retain useful bond orpeel strength at tem
48、peratures above 60C. Some polyimidesmay have useful strengths at temperatures up to 300C.Amoretypical adhesive upper use temperature is 80 to 100C. If theexpected use temperature is above about 80C, the bondstrengths of adhesives should be verified either from vendortest data or by actual test.NOTE
49、X2.1Outgassing in accordance with Test Method E595,atstandard conditions, is performed at 125C. If operating temperatures areexpected to exceed 85 to 90C, the material should be tested foroutgassing at least 30C above the expected operating temperature.X2.3 Mechanical and Physical PropertiesNormally, sup-pliers provide data sheets that list material properties ofadhesives. This information is not directly transferable tospecifications and standards. In fact, the vendor data sheetsusually have a disclaimer that the properties ar
