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United Space Alliance, LLCMaterials 8 ProcessEngineering

Chrome= Free AluminumCoating SystemJohn H. Bailey and Jeffrey D. GugelMay 12, 2010

TM

Uni ted Spa ce A l lianceCopyright 2009 by United Space Alliance, LLC. These materials are sponsored by the National Aeronautics andSpace Administration under Contract NNJ06VA01C. The U.S. Government retains a paid-up, nonexclusive, irrevocableworldwide license in such materials to reproduce, prepare, derivative works, distribute copies to the public, andperform publicly and display publicly, by or on behalf of the U.S. Government. All other rights are reserved by thecopyright owner.

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GQvernment agency Policy on HexavalentChromium k 1 . 1 1

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OSHA has ident if ied hexavalent chrom ium as a cause ofserious, acute, and chronic exp osure hazards for personnel EPA restrictions on airborne an d l iquid release of chrom iumcontaining compounds The Under Secretary of Defense issued a M em orandum inNo vemb er 2008 ent it led "M inim izing the Use of HexavalentCh romium ", w hich directed DoD Mil itary Dep artm ents to:- "Approve u se o f a l te rnat ives w here they can pe r form adequa te ly fo rthe in tended app l ica tion and operat ing env i ronme nt"

- "Update a l l re levan t techn ica l docum ents and speci f icat ions toautho rize use of the qua l if ied al ternat ives and therefore el im inatethe use o f m ater ia ls conta in ing Cr +6"

N O T I C E ; U s e o r d i s c lo s u r e o f d a t a c o n t a i n e d o n t h i s p a g e i ss u b je c t t o t h e r e s t r i c t io n o n t h e t i t le o r f ir s t p a g e o f t h i s d o c u m e n t .

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Aerospace Aluminum Alloys Aerospace aluminum alloys used in missiles and aircraft aretypically wrought products of the 2xxx, 7xxx, and 6xxx series,in various precipitation hardened tempers These grades of aluminum are chosen for their light weightand high strengths, but require supplemental corrosionprotection methods to maximize the service life Aerospace aluminum alloys have traditionally usedhexavalent chromium compounds (Cr + s ) to mitigate corrosion

- These com pounds h ave been the p re fe r red p ro tec t ion m ethod fo raerospace a luminum a l loys- These com pounds have been used fo r ove r 50 yea rs

2N O T I C E ; U s e o r d i s c l o s u r e o f d a t a c o n t a i n e d o n t h i s p a g e i ss u b je c t t o t h e r e s t r i c t io n o n t h e t i t le o r f ir s t p a g e o f t h i s d o c u m e n t .

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C oating H istQ ry at Un ited S p a c e Alliance Solid Rocket Booster (SRB) structural hardware isconstructed primarily of 2219-T87 From the beginning of the Space Shuttle Program through themid-1990's, the SRB hardware was coated with chromate -containing Alodine1201 T I M pretreatment, and AKZO epoxytopcoats which contained lead and chromates To achieve the maximum levels of corrosion protection, allaluminum alloys used for SRB hardware have utilized a 3-partsystem comprised of:

- Convers ion Pret reatment- P r im e r- T opc oa t

3NOTICE; Use or disclosure of data contained on this page issu b j ec t to th e r es t r i c t io n o n th e t i t le o r f i r s t page o f th is d o cu m en t .

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^ V Coating History at United Space Alliance During the mid-1990's the SRB coating systems for aluminum

alloys were changed to:- Alodine 12 01 T M hexava lent chrom e convers ion pre t reatm ent- Def t chroma ted water-borne ep oxy pr im er ( lead - f ree)- De f t u re thane topcoat ( lead - f ree)

In 1999, USA began an extensive test program to qualifychrome - free pretreatment and coating systems 40 sys tems w ere eva lua ted A lo din e 5 2 0 0 T m and 5700 T M pret reatm ent , in com bination wi th chrom e -f ree pr imer and topcoat , p roved to prov ide the best corros ion pro tection

Performance criteria included Adhesion Corros ion Resis tance (Oceanf ront Atm osphere, Seaw aterIm m ers ion, Sa l t Fog, Electrochem ica l Im pedan ce Spe ct roscopy) Serv ice Environm ent and Serv ice L i fe Future Process ing (Tou ch-Up, Repai r , Re coat ) Com pat ibi li ty w i th T herm al Pro tect ion C oat ings

4N O T I C E ; U s e o r d i s c lo s u r e o f d a t a c o n t a i n e d o n t h i s p a g e i ss u b je c t t o t h e r e s t r i c t io n o n t h e t i t le o r f i r s t p a g e o f t h i s d o c u m e n t .

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Chrome -Free Replacement Testing The Alodine0 Deft Replacement project consisted of threep h a s e s

- Dow n se lect ionQualif ication

- Imp lem enta t ion Down selection consisted of:

- 40 su pp l ie rs eva luated- Phase I Test ing - S ix p re t rea tments and s ix coa t ing sys tem s- Phase I I Te st ing - Three pret reatm ents and three coat ing system swe re cho sen for qua l i fica tion

u a l if ic a t i o n t e s t in g c o n s i s t e d o f o v e r 4, 0 0 0 t e s t s :- Al l coat ing can d idates were tested w i th each pre t reatm ent cand idateand the correspond ing base line- Test ing wa s ha l ted fo r cand ida tes tha t were found to beunsat isfactory- Proce ssabi li ty (Perso nne l Co nsidera t ions , Re pea tabi li ty) 5NOTICE; Use or disclosure of data contained on this page issu b j ec t to th e r es t r i c t io n o n th e t i t l e o r fi r s t page o f th is d o cu m en t .

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Chrome - Free ReplacementImplementationAM Implementation consisted of:-Va l idat ion on Fl ight Structures (proce ss val idat ion - not f low n)

No process ing anom al ies M eet ing acceptance requ i rem ents

- Process ing eng ineer ing chan ge pap er to incorpora te changein to eng ineer ing drawings and proced ures- Ve r i ficat ion on f light s t ructures ( f lown )

- L i fe C yc le M oni tor ing Sur face m app ing fo r p i ts and gene ra l cor ros ion

Co nt inu ing to gather per form ance da ta

6NOTICE; Use or disclosure of data contained on this page issu b j ec t to th e r es t r i c t io n o n th e t i t l e o r fi r s t page o f th is d o cu m en t .

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Chrome -Free Professing After this extensive three yea r evaluat ion, US A co nverted tochromate - f ree pretreatment and p rim er in 200 2 forprocessing SR B h ardware for the Space Shutt le Program USA's tes ting show ed that moving aw ay f rom Cr + s , w hi lemeeting baseline corrosion protection performance

requirements- Re quires a system , as opposed to ind iv idua l com ponents- M ax imum cor ros ion p ro tec t ion requ i res p re trea tment , p r im er ,and topcoat

SRB hardw are has been f ly ing for the pas t 7 years usingchrom e - free system s, with no deleterious effects

N O T I C E ; U s e o r d i s c l o s u r e o f d a t a c o n t a i n e d o n t h i s p a g e i ss u b je c t t o t h e r e s t r i c t io n o n t h e t i t le o r f ir s t p a g e o f t h i s d o c u m e n t .

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V Chrome -Free Processing (cont,)

The chrom e - f ree pretreatm ent and p r im er / topco at systemsare being targeted for use on future m anned sp ace f lightvehicles As a result of USA's p roactive approach to f inding an

environm entally fr iendly solution to m itigate the hexavalentchrome issue on SRB hardw are- US A has becom e a recogn ized leader w i th in the aerospacecom m un i ty in the rem ova l o f Cr + 6 f rom coat ing waste s tream s- USA is t he on ly ae rospace com pany a t Kennedy Space C en te r to beusing chrom e - f ree convers ion pre t reatm ent and pr im er for fl igh thardware

N O T I C E ; U s e o r d i s c l o s u r e o f d a t a c o n t a i n e d o n t h i s p a g e i ss u b je c t t o t h e r e s t r i c t io n o n t h e t it le o r f ir s t p a g e o f t h i s d o c u m e n t .s

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C hrom e - Free C o at ing Sys tem (co n t ,)9 9 1 .0

Current Coat ing System U sed on SR B Hardware Chrom ate - Free Pr im er and Topco at System

Ch rom e - free pr imer and topcoat we re chosen through test ing asthe p r im ary coa t ing sys tem fo r a lum inum S RB hardware due to Ease o f m ix ing Non-hazardou s d isposa l Ease of app l icat ion (8 hou r pot l ife for both pr im er andtopcoat)

Operationa l personnel pre fer th is system due to reduced exposureto hazardous w astes and extended w ork ing li fe

10N O T I C E ; U s e o r d i s c lo s u r e o f d a t a c o n t a i n e d o n t h i s p a g e i ss u b j e c t to t h e r e s t r ic t i o n o n t h e t it le o r f ir s t p a g e o f t h i s d o c u m e n t .

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Acreage Coverage of SRB ComponentsM&A-MI M SRB Aft Skirt coated with Alodine 5700 T m and chrome - freeprimer / topcoat protective finish

I lN O T I C E ; U s e o r d i s c l o s u r e o f d a t a c o n t a i n e d o n t h i s p a g e i ss u b je c t t o t h e r e s t r i c t io n o n t h e t i t le o r f ir s t p a g e o f t h i s d o c u m e n t .

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Acreage Coverage of SRO Components

SR B forw ard s t ructures coated w i th Alodine0 5700 T " " a n dchrom e -free prim er / top coat pro tect ive f inish

12N O T I C E ; U s e o r d i s c lo s u r e o f d a t a c o n t a i n e d o n t h i s p a g e i ss u b je c t t o t h e r e s t r i c t io n o n t h e t i t le o r f ir s t p a g e o f t h i s d o c u m e n t .

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Benefits of Chrome - Free Coatings

Benefits of Chromate - Free Pretreatment Systems-Co nforms to EPA an d OSHA g u ide lines concern ing hexava lentchromiumSup ports the new DoD d i rective concern ing the reduct ion o fhexava lent chrom eRe duces in-process cos ts due to hand l ing / sa fe ty issues- Redu ces d i sposa l cos tsM eets or exceeds corros ion pro tect ion (as a system) com paredto hexava len t ch romium sys tem s

Benefits of Chromate - Free Primer Systems-Rem oves ch rome com pounds f rom p rocess ing s t ream- M eets o r excee ds pe r fo rm ance, repeatab il it y , and adhes ion ascom pared to chroma te base l ine coat ing system sProv ides c orros ion pro tect ion foundat ion for po lyure thanetopcoats1 3N O T I C E ; U s e o r d i s c lo s u r e o f d a t a c o n t a i n e d o n t h i s p a g e i ss u b je c t t o t h e r e s t r i c t io n o n t h e t it le o r f ir s t p a g e o f t h i s d o c u m e n t .

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Why is USA Ys Chrome -Free CoatingSystem a Good Solution? Eliminates chromates from waste processing streams Reduces worker exposure to hazardous materials Pretreatment satisfies baseline adhesion properties forprimers and adhesives' Pretreatment with paint systems satisfies corrosionresistance baseline requirements Pretreatment has an extended window for primer application

Pretreatment is compatible with all SRB coating systems Pretreatment may be applied to all aluminum surfaces

14NOTICE; Use or disclosure of data contained on this page issu b j ec t to th e r es t r i c t io n o n th e t i t le o r f i r s t page o f th is d o cu m en t .

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l^ NextGeneration of Pretrea ents_ ' a. & After 7 years of chrome-free processing, USA is evaluating

new chrome -free coatings for aerospace use Electrodeposited Inorganic Titanium Oxides show promise asthe next generation of chromate - free pretreatment

- This product is deposi ted by coo l p lasm a- Depo si t appl ied to a lum inum and t i tan ium al loys, and a lum in izedi ron-base substrates- Cor ros ion res is tant- Provides su bstrate corrosion protec t ion- W ear res is tan t- H igh he at res is tance- Chem ica l res is tance

- Coat ing th ickness o f severa l m icrons- Found at ion for topco ats, adhe sives, or therm al protection system s- M ay e l im ina te the need fo r o rgan ic topcoats

I sN O T I C E ; U s e o r d i s c l o s u r e o f d a t a c o n t a i n e d o n t h i s p a g e i ss u b je c t t o t h e r e s t r i c t io n o n t h e t i t le o r f ir s t p a g e o f t h i s d o c u m e n t .