Greening DoD Surface Finishing Operations

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1 Teaming website: Greening DoD Surface Finishing Operations Keith Legg Rowan Technology Group Libertyville, IL 4/2008 Washington Forum Keith Legg

2 And, has thou slain the Jabberwock? We still mostly use the old standbys Vats of Cd and hard chrome Oceans of chromate conversion coatings Barrels of chromated primer Alternatives moving to production Stainless steels, composites Electroplated Al, ZnNi Chrome-free primers Chromate-free metallic ceramics

3 Recent workshops Surface Finishing and Repair Issues for Sustaining New Military Aircraft, Tempe, AZ, Feb 2008 Chromate Alternatives for Metal Treatment and Sealing, Ogden, UT, May 2007 Metal Finishing - Addressing Emerging Regulatory Requirements, SERDP/ESTCP Partners in Environmental Technology Symposium, Washington, November 2006 DoD Metal Finishing Workshop, Washington DC, May under Meetings

4 Chromate conversion alternatives Ogden chromates workshop, May 2007 DoD/industry collaboration Many commercial alternatives available Cr 3+ and non-cr Most Cr 3+ treatments contain other inhibitors (e.g. V) and nanoparticles See Ogden meeting report Some are equivalent to chromates All require much more careful prep and cleaning of surface Better training Better cleaners? Ways of measuring cleanliness?

5 Surface Finishing and Repair Workshop Temp, AZ, Feb 08 Purpose Get answers to question of how to sustain systems with the various new materials, coatings and surface treatments Provide a forum for engineers to interact First of the ASETS Defense follow-on from the HCAT meetings Advanced Surface Engineering Technologies for a Sustainable Defense

6 Major changes and challenges Changes Challenges Non Cr primers taking over Cd could be mostly replaced today with Al and ZnNi HVOF taking over from hard Cr For externals Electroless Ni for internals Quick cure (UV cure) topcoats Under development Low T powder coat primers Alloys to replace CuBe NDI to see everything Not comfortable with having no Cr 6+ in the finish Non-chromate finishes require much more careful prep Replace a single technology or material with several Training Qual, Qual, Qual!!

7 Alloys All new actuators are high strength stainless steel or Ti S53 high strength CRES steel for Landing Gear No Cd Much better corrosion Still using Cd for galvanic compatibility with Al airframes CuBe bushings F-35 has replaced CuBe with Nitronic 60 throughout aircraft, except weapons bay door where >2.5 dia bushings are outside size limits for Nitronic Biodur (CoCrMo) looks better than CuBe in practice, even though Fcy is lower This project clearly demonstrates the power and speed of computational metallurgy Materials by Design rather than Materials by Luck New materials in months, not decades Designed for landing gear, but may find earlier uses in actuators Material cost is an issue for OEMs Cost savings accrue to users, not OEMs

8 Cd plate alternatives ZnNi electroplate Boeing and Dipsol have developed LHE ZnNi Few levelers, brighteners Looks good for many applications As good as or better than Cd Can be put into standard plating line Both are drop-ins AlumiPlate has best performance but highest capital cost AlumiPlate Overall best technical Cd alternative Becoming used on F-35, F-22 Validation/qual under way for landing gear No H embrittlement Best SO 2 salt fog, SCC, fatigue performance Requires enclosed line Sole source

9 Cd Alternative Coating Corrosion Performance on 4340 Steel* Coating Stress 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 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) Method RSL Method ASTM E 466; R=0.1; f=10/s Debit Debit --- ASTM E 466; R=0.1; f=10/s ASTM G85.A4 * Steve Brown, Tempe, 08

10 AlumiPlated connectors

11 Hard chrome plating alternatives HVOF has largely taken over for external areas of aircraft components All new commercial and military landing gear programs specify HVOF WC-Co or WC-CoCr Including F-35, A380, B787 Implementation at Hill AFB Phase 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

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13 Chrome replacement on interiors Can HVOF coat diameters deep For deeper holes, complex shapes increasing use of electroless Ni-P Usually recommend low-p for best hardness without heat treat Most airframe alloys cannot take C Nanophase Co-P pulse electroplate developed for internal chrome replacement From Integran LLC in Toronto In final stages of testing this year

14 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 Lockheed engineers now need special permission to use chromated primers 44GN098 used for Apache Longbow helicopter

15 Powder coating Painting and curing is always slow and limits turnaround speed in manufacture and maintenance Powder coating much better performance, but too high a cure temperature New Low T Cure Powder Coat under transition 250 F, 30 mins; being reduced to 175 F and moving from thermal cure to UV cure Inhibitor package, eliminates VOCs and primers New UV cured topcoats under development by Foster-Miller Dry-fly time from days to minutes

16 Mg gearboxes Always a bad corrosion problem Tagnite now being used in place of Dow Cr 6+ processes Better performance, less corrosion, less easily damaged Beginning to use AlumiPlated studs 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

17 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 New teaming web site for all data and team interactions still at but runs on different software

18 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 decisions There are numerous web sites for different agencies, but none contain real engineering data, production details, etc. as site does New ASETS Defense passworded website is MS SQL based and Database will run off it for now Establishment 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

19 Surface Engineering Database SERDP and ESTCPgenerated data All other releasable DoD data 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. Start with chromate conversion alternatives

20 Summary The main challenges are not lack of alternatives, but getting alternatives qualified Many clean technologies often perform better than current methods, BUT They are lot more sensitive to surface condition and process control They require more care and training Clean technologies are moving out into the world BUT have to move into comfort zone Growing experience helps Access to good engineering data helps

21 More info Chrome-Free Aircraft Finishing by Keith O. Legg March 1,