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Keith Legg 847-680-9420www.hazmat-alternatives.com
http://www.asetsdefense.org/Teaming website: www.materialoptions.com
Keith LeggRowan Technology Group
Libertyville, IL4/2008 Washington Forum
Greening DoD Surface Finishing Operations
And, has thou slain the Jabberwock?
We still mostly use the old standbys
Vats of Cd and hard chromeOceans of chromate conversion coatingsBarrels of chromated primer
Alternatives moving to production
Stainless steels, compositesElectroplated Al, ZnNiChrome-free primersChromate-free metallic ceramics
Recent workshops
Surface Finishing and Repair Issues for Sustaining New Military Aircraft, Tempe, AZ, Feb 2008Chromate Alternatives for Metal Treatment and Sealing, Ogden, UT, May 2007Metal Finishing - Addressing Emerging Regulatory Requirements, SERDP/ESTCP Partners in Environmental Technology Symposium, Washington, November 2006DoD Metal Finishing Workshop, Washington DC, May 2006http://www.materialoptions.com under Meetings
Chromate conversion alternatives – Ogden chromates workshop, May 2007
DoD/industry collaborationMany commercial alternatives available
Cr3+ and non-CrMost Cr3+ treatments contain other inhibitors (e.g. V) and nanoparticlesSee Ogden meeting report
Some are equivalent to chromatesAll require much more careful prep and cleaning of surface
Better trainingBetter cleaners?Ways of measuring cleanliness?
Surface Finishing and Repair WorkshopTemp, AZ, Feb 08
PurposeGet answers to question of how to sustain systems with the various new materials, coatings and surface treatmentsProvide a forum for engineers to interactFirst of the ASETS Defense follow-on from the HCAT meetings
Advanced Surface Engineering Technologies for a Sustainable Defense
Major changes and challenges
ChangesNon Cr primers taking overCd could be mostly replaced today with Al and ZnNiHVOF taking over from hard Cr
For externalsElectroless Ni for internals
Quick cure (UV cure) topcoatsUnder development
Low T powder coat primersAlloys to replace CuBeNDI to see everything
ChallengesNot comfortable with having no Cr6+ in the finishNon-chromate finishes require much more careful prepReplace a single technology or material with severalTraining
Qual, Qual, Qual !!
Alloys
All new actuators are high strength stainless steel or Ti
No CdMuch better corrosionStill using Cd for galvanic compatibility with Al airframes
CuBe bushingsF-35 has replaced CuBewith Nitronic 60 throughout aircraft, except weapons bay door where >2.5” diabushings are outside size limits for NitronicBiodur (CoCrMo) looks better than CuBe in practice, even though Fcy is lower
S53 high strength CRES steel for Landing Gear
This project clearly demonstrates the power and speed of computational metallurgy
Materials by Design rather than Materials by LuckNew materials in months, not decades
Designed for landing gear, but may find earlier uses in actuatorsMaterial cost is an issue for OEMs
Cost savings accrue to users, not OEMs
Cd plate alternatives
ZnNi electroplateBoeing and Dipsol have developed LHE ZnNi
Few levelers, brightenersLooks good for many applications
As good as or better than CdCan be put into standard plating line
AlumiPlateOverall best technical Cd alternativeBecoming used on F-35, F-22Validation/qual under way for landing gearNo H embrittlementBest SO2 salt fog, SCC, fatigue performanceRequires enclosed lineSole source
Both are drop-insAlumiPlate has best performance but highest capital cost
Cd Alternative Coating Corrosion Performance on 4340 Steel*
CoatingStress
Corrosion Cracking (Koscc)
SCC Ranking Air Fatigue Ranking
Corrosion Fatigue Ranking
Acid SO2 Salt Fog, ASTM
G85.A4
Sputtered Al Not Tested --- --- --- ≥IVD
Electroplated Al
101.0 Best Best Best Best (bare)
IVD-Al 52.7 Comparable to Cd
Best Best Least among Al coatings
Cd 49.5 CONTROL CONTROL CONTROL CONTROL
LHE Zn-Ni 56.2 > Cd Debit Debit > Cd (bare); Comparable
(painted)
Zn-6Ni 36.8 OK (less data)
Debit Debit ---
Method RSL Method ASTM E 466; R=0.1; f=10/s
ASTM E 466; R=0.1; f=10/s
ASTM G85.A4
* Steve Brown, Tempe, 08
Hard chrome plating alternatives
HVOF has largely taken over for external areas of aircraft componentsAll new commercial and military landing gear programs specify HVOF WC-Co or WC-CoCr
Including F-35, A380, B787
Implementation at Hill AFBPhase I -Converted 38 components (1-06 to 4-07)Phase II-Converting 128 components (1-07 to 6-08)Phase III-238 parts identified, work commencing
Chrome replacement on interiors
Can HVOF coat 1-1.5 diameters deepFor deeper holes, complex shapes increasing use of electroless Ni-P
Usually recommend low-P for best hardness without heat treatMost airframe alloys cannot take 300-400C
Nanophase Co-P pulse electroplate developed for internal chrome replacement
From Integran LLC in TorontoIn final stages of testing this year
Wearin’ o’ the green – F-35 primer chrome-free
•Approved Deft 44GN098 Cr-free primer as F-35 Structural Primer•NAVAIR Completed Qualification to Mil-PRF-85582•Lockheed engineers now need special permission to use chromated primers•44GN098 used for Apache Longbow helicopter
Powder coating
Painting and curing is always slow and limits turnaround speed in manufacture and maintenancePowder coating much better performance, but too high a cure temperatureNew Low T Cure Powder Coat under transition
250°F, 30 mins; being reduced to 175°F and moving from thermal cure to UV cureInhibitor package, eliminates VOCs and primers
New UV cured topcoats under development by Foster-Miller
Dry-fly time from days to minutes
Mg gearboxes
Always a bad corrosion problemTagnite now being used in place of Dow Cr6+ processes
Better performance, less corrosion, less easily damaged
Beginning to use AlumiPlatedstuds and fittings instead of Cd
Can re-Tagnite or re-anodize for better performance
Developing cold spray Al for repair (ARL, DSTO)
H-60 Main Transmission Housing showing areas most susceptible to corrosion
ASETS Defense
HCAT has segued into ASETSDefense(Advanced Surface Engineering Technologies for a Sustainable Defense)New name reflects broader mission for all clean surface technologies
New web site under construction from old HCAT.org, now called www.asetsdefense.orgNew teaming web site for all data and team interactions still at www.materialoptions.combut runs on different software
Surface Engineering Database
To implement clean technologies quickly and efficiently engineers need ready access to engineering data on surface engineering materials and processes adequate for making engineering decisionsThere are numerous web sites for different agencies, but none contain real engineering data, production details, etc. as www.materialoptions.com site doesNew ASETS Defense passworded website is MS SQL based and Database will run off it for nowEstablishment of readily available engineering data for some material will drive release of commercial engineering data for others
If companies want to sell it users need to know all about it
•SERDP and ESTCP-generated data•All other releasable DoDdata we can get our hands on•All commercial data companies are willing to give us•Links to data held by others, e.g. NASF, NMFRC, etc.
Surface Engineering Database
Start with chromate conversion alternatives
Summary
The main challenges are not lack of alternatives, but getting alternatives qualifiedMany clean technologies often perform better than current methods, BUT
They are lot more sensitive to surface condition and process controlThey require more care and training
Clean technologies are moving out into the world BUT have to move into comfort zone
Growing experience helpsAccess to good engineering data helps
More info
http://www.pfonline.com/articles/030801.html
Chrome-Free Aircraft Finishing
by Keith O.Legg
March 1, 2008
http://www.finishingtodaymag.com/CDA/Articles/Cover_Story/
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