1、Designation: E 1997 07Standard Practice for theSelection of Spacecraft Materials1This standard is issued under the fixed designation E 1997; 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 par
2、entheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 The purpose of this practice is to aid engineers, design-ers, quality and reliability control engineers, materials special-ists, and systems design
3、ers in the selection and control ofmaterials 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 p
4、erformance 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
5、 may result 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:2E 595 Test Method for Total Mass Loss and CollectedVolatile Condens
6、able Materials from Outgassing in aVacuum EnvironmentG64 Classification of Resistance to Stress-CorrosionCracking of Heat-Treatable Aluminum Alloys2.2 Marshall Space Flight Center (MSFC) Standard:MSFC-SPEC-522 Design Criteria for Controlling StressCorrosion Cracking32.3 Military Standards:4MIL-STD-8
7、89 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 Selection52.5 Federal Standard:QQ-A-250 Aluminum and Aluminum Alloy Pla
8、te 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 contractual agree-ments, functional performance requirements for particularprog
9、rams 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 possible performance and design constraints andrequirements
10、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 missions.Although many of the suggestions andcautions are appl
11、icable to both unmanned and manned space-craft, manned systems have additional constraints and require-ments for crew safety which may not be addressed adequatelyin unmanned designs. Because of the added constraints andconcerns for human-rated systems, these systems are notaddressed in this practice
12、.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 definitionincludes defining the range of temperature expos
13、ure, 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, structuralloads, and so forth. Materials suitable for one
14、orbit or mission1This 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 Dec. 1, 2007. Published January 2008. Originallyapproved in 1999. Las
15、t previous edition approved in 2003 as E 1997 99(2003)e1.2For 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.3Mar
16、shall Space Flight Center, AL 35812.4Available from the Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20402.5European Space Agency, 810, Rue Mario-Nikis, 75738 Paris Cedex, France.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1
17、9428-2959, United States.Copyright by ASTM Intl (all rights reserved); Fri Feb 27 01:29:57 EST 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.environment may be unsuitable for others. The applicationsand requirements will define the suita
18、bility of the materials.4.2 Low Earth Orbit (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 f
19、requent excursionsinto and out of the earths 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 fli
20、ght profile than equatorial orbitsand have 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,
21、 solar flares, andrelatively high levels of electromagnetic solar radiation (ultra-violet, VUV photons, and X-rays). The number of thermalcycles is less and may be over a narrower temperature rangethan low earth orbit. Meteoroids also should be considered butare less likely to be significant compare
22、d to the manmadedebris found in low orbits. Design life in orbit typically is 5 to15 years, with recent designs ranging from 10 to 17 years.4.4 Interplanetary (Out-of-Earth Orbit)In addition to thethermal extremes and environments of synchronous orbit, inthe interplanetary environment, temperatures
23、may be moreextreme, and micrometeoroids, 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 t
24、o 30years.5. Materials to Avoid5.1 Certain 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
25、 Metals with High Vapor Pressure in Vacuum 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 e
26、ven moderately, they will vacuum metal-lize 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 i
27、n electrical components or break offand become conductive contaminants. Some other metals suchas cadmium and zinc also can grow whiskers and should not beused.5.1.2 Stress-Corrosion Sensitive MetalsMetals, which arestress-corrosion sensitive, should be avoided. Examples are2024 T6 and 7075 T6 Alumin
28、um, 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 can be used if loaded incompression or if loade
29、d to low sustained tensile stress levels,typically no more than 25 % of yield strength (see Classifica-tion G64and MSFC-SPEC-522).5.1.3 Materials Forming Galvanic CouplesMaterial com-binations, which form galvanic couples greater than 0.5 evwhen exposed to a temperature and humidity controlledenviro
30、nment, 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 corrosion. Some alloys, such as magnesium,magnesium
31、 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 must be evaluated for galvanic potential,since car
32、bon 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 material, or adding a material that is compatible wit
33、h 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 very low orvery high temperatures and some metal
34、s 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 basicor acidic environments. Steels, particula
35、rly 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, or do nothave a history of consistency of prop
36、erties 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 as elevatedtemperature service may require use o
37、f 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 inspected easily for hiddendefects.5.1.6 Materials Th
38、at Have Excessive OutgassingIf thematerials have high collected volatile condensable materials(CVCM) or total mass loss (TML) when exposed at 125C andtested, they generally are excluded from spacecraft applica-tions. Normal acceptance limits for outgassing according toTest Method E 595 are no higher
39、 than 1.0 % TML and nohigher than 0.10 % CVCM. Some of these materials releaseE1997072Copyright by ASTM Intl (all rights reserved); Fri Feb 27 01:29:57 EST 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.condensates that react adversely wi
40、th solar radiation or radia-tion and vacuum and may degrade sensitive surfaces. Otherscan contaminate surfaces or equipment such that functionalityis impaired. High mass loss can indicate a loss or propertiesand functionality in space. Sometimes, a material will haveacceptable outgassing per normal
41、requirements, but it may bein a particularly sensitive location, or the outgassing productmay have an adverse effect on specific sensitive equipment.These conditions can require establishing lower levels foracceptable outgassing or may require analysis of outgassedcomponents and evaluation of the ac
42、ceptability for the specificapplication.NOTE 1The test is defined as performed at 125C unless clearly statedotherwise; therefore, acceptability is limited to exposures below 125C.The test temperature of 125C was assumed to be significantly above theexpected operating temperature in service. If expec
43、ted operating tempera-tures exceed 65 to 70C the test temperature should be increased. It issuggested that the test temperature be 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
44、metals, such aszinc and cadmium, do exhibit high vapor pressure at relatively low(1000-pi design loads) require specifictraining to apply the adhesive, including surface preparationand process controls for consistency and effective, reliablestrength.X2.2 General Usage PrecautionsUsage precautions mu
45、stbe observed to avoid undesirable or unacceptable results andeven system failures. The importance of thermal sensitivitymust not 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. Epoxies
46、often have brittle points in the 20 to 60C range. Epoxiesshould not be used in direct contact with ceramic parts, such asceramic-cased diodes when usage temperatures are low. Aflexible intermediate material must be applied to prevent brittlefracture of the ceramic. Silicones are normally flexible at
47、temperatures as low as 110C. Flexible silicones should beused rather than epoxies to bond ceramics for low temperatureapplications 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. Hi
48、gh temperatures result in significant loss in bondstrength for adhesives. Few adhesives retain useful bond orpeel strength at temperatures above 60C. Some polyimidesmay have useful strengths at temperatures up to 300C.Amoretypical adhesive upper use temperature is 80 to 100C. If theexpected use temp
49、erature is above about 80C, the bondstrengths of adhesives should be verified either from vendortest data or by actual test.NOTE X2.1Outgassing in accordance with Test Method E 595, 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 transfe
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