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ASETSDefense Technica

Rowan Technol

Libe

8/2009 DLA Shelf Life Sy

Hexavalent chrome issues and options
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Topics

Usage of Cr6+ in DoDCr6+ as a shelf life issueRegulatory issuesAlternatives in development, qualifInformation resources
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Usage
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Cr6+ usage in DoD

Cr6+‐containing coatings Cr6+ processes, 

Chromate conversion coatingsChromate sealersChromated primersChromate washesChromated metallic‐ceramics

Hard chrome Chromic acid Chromic acid 

Cr6+ (CrVI, hexavalent chrome, chromate) is our primary c

Makes coating systems self-healin

Cr6+-containing coatings are a problem for sustainment (repaint, t

Cr6+ processes are only a problem for OEM an
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Typical coating stackups

Steel

Cd plate

Chromate conversion coat

Chromated primerHigh VOC topcoat

Aluminum a

Anodize (or 

Chromate conve

Chromated pHigh VOC to
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Cr6+ makes production an

sustainment difficult

A problAircraft 25μg m

5μg m-3 

A problMaintain

dust
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Cr6+ as shelf life issue

Items m

 Mu Wit

coa

heacan 

UAVs m

of the b
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ESOH
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Regulatory issues

OSHA Cr6+ PEL 5μg m‐3RoHS

 Cr6+ < 0.1at% Military and aerospace exempt

Upcoming US RoHS?

 HR 2420, no defense, aerospace exemption 

REACH (no Defense Exemption as of now, e

 Sodium Dichromate is now a candidate sub

(for authorization)

 But not a priority substance because easy t ECHA hints that may include all chromates  Issue for sustainment of our systems in Eur

REACH and RoHS issues for foreign sales
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DoD Memo on Cr6+

April 8 ‘09 OS

restricting Cr6

cost‐effective satisfactory p

Requires Prog

Officer (PEO) Control and PExecutive (CCacceptable al

Effect will be 

of Cr6+‐free co

production m
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Alternatives under development,

qualification, implemented
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Cr6+‐free coatings

Material Status of alternatives

Chromate conversion coating

Trivalent chrome and non-Cr commergood as Cr6+. Used on cars, Boeing 7

systems, USAF T.O. 1-1-8 Prekote

Chromate primers Non-Cr primers commercially availabl

Apache. Performance good on Cr6+ co

toward total non-Cr6+

Chromate finish system Low temperature powder coat and UV 

validation to replace primer/topcoat fo

No Cr6+, low VOC. In development

Chromate conversion of Mg

Tagnite now used on EFV gearbox, socomponents. Performance much bette

and anodize. Limited DoD use. Keron

Metallic-ceramics Low-Cr and non-Cr available commer

uncertain

Chromate washes Direct-to-metal used for MRAP. Poor 
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Cr6+‐free processes

Material StatusHard chrome plating HVOF on F-35 landing gear, all new c

landing gear. Being implemented for Electroplates such as nCo-P in valida

Chromic acid anodize TFSAA approved by NAVAIR, BSAA b
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How well do alternatives 

In general finish systems not

quite as good as chromate

 But getting a lot better Total Cr6+‐free finish systems

not there yet, but probably will

be as good a Cr6+ in <5yrs

 Total Cr6+‐free finish systems

can work today on low‐riskparts

Tend to be harder to do, easier

to mess up

 Much more sensitive to process

conditions

 Requires better QC, inspection

HVOF m

hard ch

Tagnite 

HAE, D

Cr6+ sea

primer chroma

Deft ha

finish. S
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What does the future ho

Move toward chrome‐free primer a

chromate conversion over 5‐10 yea

 Immediately for new weapons systems

Move toward Cr6+‐free UV cure finisand vehicles next 5 years or so

 Much faster turnaround, eliminates pr

HVOF in place of hard chrome on allanding gear, many hydraulics and s

systems

 HVOF for repair on most legacy landing 

hydraulics
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ASETSDefense sources of informa
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ASETSDefensehttp://www.asetsdefens
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Quick Links basic inform
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Database – Simple searc

Designed to answer question “What alternative to hard chrome (etc) is available (authorized, implemented, spec’d) for my type of system and application?”
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Detail search

Search for specific materials, systemtests, people, organizations

corrosion
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Database Documents
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ASETSDefense ’09Coming in September

ASETSDefense ’09: 

Engineering for 

Defense

Denver, August 31‐ 

Aircraft, ships, vAlternatives to csealers, convers

paint systems, h

Stackups, hydra

electrical conne