ASTM_E_2089_-_15.pdf

Designation:E208915Standard Practices forGround Laboratory Atomic Oxygen Interaction Evaluation ofMaterials for Space Applications1This standard is issued under the fixed designation E2089;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 The intent of these practices is to define atomic oxygenexposure procedures that are intended to minimize variabilityin results within any specific atomic oxygen exposure facilityas well as contribute to the understanding of the differences inthe response of materials when tested in different facilities.1.2 These practices are not intended to specify any particu-lar type of atomic oxygen exposure facility but simply specifyprocedures that can be applied to a wide variety of facilities.1.3 The values stated in SI units are to be regarded as thestandard.1.4 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.Terminology2.1 Definitions:2.1.1 atomic oxygen erosion yieldthe volume of a materialthat is eroded by atomic oxygen per incident oxygen atomreported in cm3/atom.2.1.2 atomic oxygen fluencethe arrival of atomic oxygento a surface reported in atoms/cm22.1.3 atomic oxygen fluxthe arrival rate of atomic oxygento a surface reported in atomscm2s1.2.1.4 effective atomic oxygen fluencethe total arrival ofatomic oxygen to a surface reported in atoms/cm2,whichwould cause the observed amount of erosion if the sample wasexposed in low Earth orbit.2.1.5 effective atomic oxygen fluxthe arrival rate of atomicoxygen to a surface reported in atomscm2s1,which wouldcause the observed amount of erosion if the sample wasexposed in low Earth orbit.2.1.6 witness materials or samplesmaterials or samplesused to measure the effective atomic oxygen flux or fluence.2.2 Symbols:Ak=exposed area of the witness sample,cm2As=exposed area of the test sample,cm2Ek=in-space erosion yield of the witness material,cm3/atomEs=erosion yield of the test material,cm3/atomfk=effective flux,atoms/cm2/sFk=effective fluence,total atoms/cm2Mk=mass loss of the witness coupon,g3.Significance and Use3.1 These practices enable the following information to beavailable:3.1.1 Material atomic oxygen erosion characteristics.3.1.2 An atomic oxygen erosion comparison of four well-characterized polymers.3.2 The resulting data are useful to:3.2.1 Compare the atomic oxygen durability of spacecraftmaterials exposed to the low Earth orbital environment.3.2.2 Compare the atomic oxygen erosion behavior betweenvarious ground laboratory facilities.3.2.3 Compare the atomic oxygen erosion behavior betweenground laboratory facilities and in-space exposure.3.2.4 Screen materials being considered for low Earthorbital spacecraft application.However,caution should beexercised in attempting to predict in-space behavior based onground laboratory testing because of differences in exposureenvironment and synergistic effects.4.Test Specimen4.1 In addition to the material to be evaluated for atomicoxygen interaction,the following four standard witness mate-rials should be exposed in the same facility using the sameoperating conditions and duration exposure within a factor of3,as the test material:Kapton(R)2H or HN polyimide,tetrafluoroethylene(TFE)-fluorocarbon fluorinated ethylene1These practices are under the jurisdiction of ASTM Committee E21 on SpaceSimulation and Applications of Space Technology and are the direct responsibilityof Subcommittee E21.04 on Space Simulation Test Methods.Current edition approved Oct.1,2015.Published October 2015.Originallyapproved in 2000.Last previous edition approved in 2014 as E2089 00(2014).DOI:10.1520/E2089-15.2Kapton(R)and DuPont(TM)are trademarks or registered trademarks of E.I.DuPont de Nemours and Company.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 propylene(FEP),low-density polyethylene(PE),and pyrolyticgraphite(PG).The atomic oxygen effective flux(inatomscm2s1)and effective fluence(in atoms/cm2)for Kap-ton H or HN polyimide should be reported along with the massor thickness loss relative to Kapton H or HN polyimide for thetest material,TFE-fluorocarbon FEP,PE,and PG.For atomicoxygen interaction testing at effective fluences beyond 2 1021atoms/cm2,Kapton H polyimide has been recommended in thepast,however E.I.du Pont de Nemours and Company(DuPont(TM2)has discontinued its manufacture.Kapton H polyimideis the preferred replacement,but Kapton HN polyimide con-tains atomic oxygen-resistant inorganic particles which beginto protect the underlying polyimide,thus resulting in