ASTM E1997-99
(Practice)Standard Practice for the Selection of Spacecraft Materials
Standard Practice for the Selection of Spacecraft Materials
SCOPE
1.1 The purpose of this practice is to aid engineers, designers, quality and reliability control engineers, materials specialists, and systems designers in the selection and control of materials and processes for spacecraft, external portion of manned systems, or man-tended systems. Spacecraft systems are very different from most other applications. Space environments are very different from terrestrial environments and can dramatically alter the performance and survivability of many materials. Reliability, long life, and inability to repair defective systems (or high cost and difficulty of repairs for manned applications) are characteristic of space applications. This practice also is intended to identify materials processes or applications that may result in degraded or unsatisfactory performance of systems, subsystems, or components. Examples of successful and unsuccessful materials selections and uses are given in the appendices.
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Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 1997 – 99
Standard Practice for the
Selection of Spacecraft Materials
This standard is issued under the fixed designation E 1997; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2.5 Federal Standard:
QQ-A-250 Aluminum and Aluminum Alloy Plate and
1.1 The purpose of this practice is to aid engineers, design-
Sheet, Federal Specification for
ers, quality and reliability control engineers, materials special-
ists, and systems designers in the selection and control of
3. Significance and Use
materials and processes for spacecraft, external portion of
3.1 This practice is a guideline for proper materials and
manned systems, or man-tended systems. Spacecraft systems
process selection and application. The specific application of
are very different from most other applications. Space environ-
these guidelines must take into account contractual agree-
ments are very different from terrestrial environments and can
ments, functional performance requirements for particular
dramatically alter the performance and survivability of many
programs and missions, and the actual environments and
materials. Reliability, long life, and inability to repair defective
exposures anticipated for each material and the equipment in
systems (or high cost and difficultly of repairs for manned
which the materials are used. Guidelines are not replacements
applications) are characteristic of space applications. This
for careful and informed engineering judgment and evaluations
practice also is intended to identify materials processes or
and all possible performance and design constraints and
applications that may result in degraded or unsatisfactory
requirements cannot be foreseen. This practice is limited to
performance of systems, subsystems, or components. Ex-
unmanned systems and unmanned or external portions of
amples of successful and unsuccessful materials selections and
manned systems, such as the Space Station. Generally, it is
uses are given in the appendices.
applicable to systems in low earth orbit, synchronous orbit, and
2. Referenced Documents interplanetary missions. Although many of the suggestions and
cautions are applicable to both unmanned and manned space-
2.1 ASTM Standards:
craft, manned systems have additional constraints and require-
E 595 Test Method for Total Mass Loss and Collected
ments for crew safety which may not be addressed adequately
Volatile Condensable Materials from Outgassing in a
in unmanned designs. Because of the added constraints and
Vacuum Environment
concerns for human-rated systems, these systems are not
G 64 Classification of Resistance to Stress-Corrosion
addressed in this practice.
Cracking of Heat-Treatable Aluminum Alloys
2.2 Marshall Space Flight Center (MSFC) Standard:
4. Design Constraints
MSFC-SPEC-522 Design Criteria for Controlling Stress
4 4.1 Orbital Environment—The actual environment in which
Corrosion Cracking
the equipment is expected to operate must be identified and
2.3 Military Standards:
5 defined. The exposures and requirements for material perfor-
MIL-STD-889 Dissimilar Materials
mance differ for various missions. Environment definition
MIL-HDBK-5 Metallic Materials and Elements for Aero-
5 includes defining the range of temperature exposure, number
space Vehicle Structures
and rate of thermal cycles, extent of vacuum exposure, solar
2.4 European Space Agency (ESA) Standard:
6 electromagnetic radiation particulate radiation, (trapped by the
PSS-07/QRM-0 Guidelines for Space Materials Selection
earth’s magnetosphere, solar wind, solar flares, and gamma
rays) micrometeroids, launch loads and vibration, structural
This practice is under the jurisdiction of ASTM Committee E21 on Space loads, and so forth. Materials suitable for one orbit or mission
Simulation and Applications of Space Technology and is the direct responsibility of
environment may be unsuitable for others. The applications
Subcommittee E21.05 on Contamination.
and requirements will define the suitability of the materials.
Current edition approved Jan. 10, 1999. Published May 1999.
4.2 Low Earth Orbit (Up to 100 km)—Materials in this
Annual Book of ASTM Standards, Vol 15.03.
Annual Book of ASTM Standards, Vol 03.02.
region could be exposed to trapped Van Allen belt (ionizing)
Marshall Space Flight Center, AL 35812.
radiation, solar ultraviolet radiation, corrosive attack by atomic
Available from the Superintendent of Documents, U.S. Government Printing
oxygen (A.O.), and more frequent and more extreme thermal
Office, Washington, DC 20402.
cycling and thermal shock as a result of frequent excursions
European Space Agency, 8–10, Rue Mario-Nikis, 75738 Paris Cedex, France.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E1997–99
into and out of earth shadow. Orbital impacts may be a problem when exposed to a temperature and humidity controlled
because of the large amount of debris in low orbits. Design life
environment, such as during fabrication, testing, and storage,
in orbit typically is on the order of 5 to 15 years. Inclination of should be prohibited under most circumstances. Providing
the orbit affects the service environment, that is, polar orbits
protection from electrolytes and maintaining them in a con-
have a different flight profile than equatorial orbits and have trolled environment, such as during fabrication and testing,
different profiles for radiation exposure.
inhibits galvanic corrosion. Some alloys, such as magnesium,
4.3 Synchronous Orbit (35 900 km)—Materials in this re- magnesium lithium alloys, and gold, form a galvanic couple
gion are not exposed to significant atomic oxygen or very high
with most common structural materials and must be protected
energy trapped radiation but may have more exposure to
adequately to prevent creating galvanic couples which cause
medium energy ionizing electrons and protons, solar flares, and
the anodic metal to corrode. Carbon composites are included in
relatively high levels of electromagnetic solar radiation (ultra-
the materials, which must be evaluated for galvanic potential,
violet, VUV photons, and X-rays). The number of thermal
since carbon forms galvanic couples with metals. If there is no
cycles is less and may be over a narrower temperature range
electrolyte present, galvanic couples greater than 0.5 ev are
than low earth orbit. Meteoroids also should be considered but
permissible. Galvanic protection can be obtained by preventing
are less likely to be significant compared to the manmade
electrolyte from contacting the interfaces, interposing a dielec-
debris found in low orbits. Design life in orbit typically is 5 to
tric material, or adding a material that is compatible with each
15 years, with recent designs ranging from 10 to 17 years.
of the other materials separately.
4.4 Interplanetary (Out-of-Earth Orbit)—In addition to the
5.1.4 Materials With Thermal or Environmental
thermal extremes and environments of synchronous orbit, in
Limitations—Materials that are weak or brittle at the expected
the interplanetary environment, temperatures may be more
service temperature or environment should be avoided. These
extreme, and micrometeoroids, solar wind, and cosmic rays
materials included polymeric materials used at very low or
may be critical. Ability to survive and remain functional for
very high temperatures and some metals used at low tempera-
many years is important. Probes to the inner plants typically
tures. In this context, “low” can be from -40 to -120°C and
have design lifetimes of 5 to 10 years. Those to the outer
“high” can be from 150 to 200°C for polymers. Some materials
planets and beyond may have design lifetimes of 15 to 30
are readily attacked by certain chemicals or solutions. For
years.
example, aluminum alloys should not be used in strongly basic
or acidic environments. Steels, particularly high carbon and
5. Materials to Avoid
ferritic grades, are embrittled by halogens and hydrogen.
5.1 Certain materials are known to be undesirable and
Silicones are attacked by toluene. Titanium is attacked by
should be avoided no matter what the mission. Others are of
methanol.
concern for certain missions or of more concern for some
5.1.5 Materials Diffıcult to Fabricate or Test—Materials
missions than others. In general, it is recommended that one
that are difficult to fabricate, form, test, or inspect, or do not
avoid the materials described below:
have a history of consistency of properties or performance,
5.1.1 Metals with High Vapor Pressure in Vacuum and
should be avoided. Some materials, such as ceramics and most
Unusual Behaviors—Avoid the use of metals such as mercury,
refractory metals, are relatively difficult to machine or form.
cadmium, and zinc, either as plating or monolithic metals. It is
Others are difficult to weld by conventional means. Some
important to exclude these metals both from the flight equip-
cannot be formed easily. All materials must be very carefully
ment and vacuum chambers. If these metals are used in
evaluated to assure successful, economic fabrication and that
vacuum and heated even moderately, they will vacuum metal-
the fabricated parts can be inspected easily for hidden defects.
lize both the cold walls of the chamber and any cold surfaces
on equipment in the chamber. Also, pure tin has the curious 5.1.6 Materials That Have Excessive Outgassing—If the
property of dendritic growth as a result of compressive materials have high collected volatile condensable materials
stresses, thermal or electrical gradients, forming whiskers (CVCM) or total mass loss (TML) when exposed at 125°C and
which can cause shorts in electrical components or break off tested, they generally are excluded from spacecraft applica-
and become conductive contaminants. Some other metals have tions. Normal acceptance limits for outgassing according to
similar whisker-growing properties, but not to the extent that Test Method E 595 are no higher than 1.0 % TML and no
tin has. higher than 0.10 % CVCM. Some of these materials release
5.1.2 Stress-Corrosion Sensitive Metals—Metals, which are condensates that react adversely with solar radiation or radia-
stress-corrosion sensitive, should be avoided. Examples are tion and vacuum and may degrade sensitive surfaces. Others
can contaminate surfaces or equipment such that functionality
2024 T6 and 7075 T6 Aluminum, which can be used if heat
treated to conditions, such as 2024 T81 and 7075 T73, which is impaired. High mass loss can indicate a loss or properties
are not stress-corrosion sensitive. Many brasses and some steel and functionality in space. Sometimes, a material will have
alloys also are stress-corrosion sensitive; however, even alloys, acceptable outgassing per normal requirements, but it may be
which are stress-corrosion sensitive can be used if loaded in in a particularly sensitive location, or the outgassing product
compression or if loaded to low sustained tensile stress levels, may have an adverse effect on specific sensitive equipment.
typically no more than 25 % of yield strength (see Classifica- These conditions can require establishing lower levels for
tion G 64 and MSFC-SPEC-522). acceptable outgassing or may require analysis of outgased
5.1.3 Materials Forming Galvanic Couples—Material com- components and evaluation of the acceptability for the specific
binations, which form galvanic couples greater than 0.5 ev application.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E1997–99
NOTE 1—The test is defined as performed at 125°C unless clearly stated
patibility of the materials with all fluids in which they may
otherwise; therefore, acceptability is limited to exposures at that tempera-
come into contact and with all of the fluids used, including
ture or below.
cleaning agents, solvents, and test fluids.
NOTE 2—Metallic materials do not “outgas,” but some metals, such as
5.1.14 Arc Tracking of Wires—Kaptont wire insulation is
zinc and cadmium, do exhibit high vapor pressure at relatively low
susceptible to arc tracking when used in power-carrying
(<150°C) temperatures in vacuum. (See 5.1.1.)
applications. Any damage or abrasion to this type of wire may
5.1.7 Materials That Release Undesirable Components—
cause dielectric breakdown and arcing, even in vacuum. Wire
For example, acetic acid is released when curing certain
insulations, such as Teflon-polyimide-Teflont , which are not
silicones. The acid can attack and corrode electrical wiring and
susceptible to arc tracking and have been qualified as such are
contacts and cause failures. In some applications, the alcohols
available and should be considered as replacements for Kapton
released when silicones cure may be harmful.
wire insulation.
5.1.8 Unstable Polymeric Materials—Some polymeric ma-
5.1.15 Inadequately Controlled Materials—Any material
terials may revert or change character when exposed to other
that is purchased and controlled only by vendor data sheet or
materials or to the space environment. For example, certain
material certification, or both, has questionable controls. This
silicones in contact with amine-cured epoxy can become fluid;
type of product control should be viewed with caution. Data
some polymeric materials are degraded by radiation or atomic
sheets are not assurances of performance and often are mis-
oxygen (A.O.), or both. Polyamide may become brittle in
leading. For example, a maximum use temperature of a
vacuum and lose mechanical strength. PTFE and FEP become
polymer may be given as 200°C, but at that temperature it may
brittle when exposed to radiation in vacuum. Lubricants
have low dielectric strength, poor modulus of elasticity and
containing graphite may lose lubricity in vacuum. ETFE wire
strength, excessive outgassing, or significant loss of other
insulation may become brittle and crack if heated to high
properties. Relying on vendor certifications alone can result in
temperatures and flexed or strained. Sulfur, which may be
acceptance of lots, which, in fact, fail some specific property.
present in some latex and rubber gloves, can prevent proper
Suppliers have been known to send substandard lots
...
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