Validation of HVOF WC/Co Thermal Spray Coatings As a Replacement for Hard Chrome Plating on Aircraft Landing Gear
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Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6170--04-8762 Validation of HVOF WC/Co Thermal Spray Coatings as a Replacement for Hard Chrome Plating on Aircraft Landing Gear BRUCE D. SARTWELL Surface Chemistry Branch, Chemistry Division KEITH O. LEGG Rowan Technology Group, Libertyville, IL JERRY SCHELL GE Aircraft Engines, Cincinnati, OH JOHN SAUER Sauer Engineering, Cincinnati, OH PAUL NATISHAN Center for Corrosion Science, Chemistry Division DENNIS DULL AND JOHN FALKOWSKI Boeing Corporation, Seattle, WA PHILIP BRETZ Metcut Research, Cincinnati, OH JON DEVEREAUX Naval Aviation Depot, Jacksonville, FL CRAIG EDWARDS General Atomics, Ogden, UT DONALD PARKER NASA Kennedy Space Center, Cape Canaveral, FL March 31, 2004 Approved for public release: distribution is unlimited. TABLE OF CONTENTS Table of Contents................................................................................................................iii List of Figures.....................................................................................................................ix List of Tables..................................................................................................................... xv List of Acronyms ............................................................................................................. xix Acknowledgments............................................................................................................ xxi 1. Background................................................................................................................1 1.1. References ...........................................................................................................8 2. Technology Description.............................................................................................9 2.1. Technology Development and Application.........................................................9 2.2. Process Description...........................................................................................10 2.3. Previous Testing of the Technology..................................................................13 2.4. Advantages and Limitations of the Technology ...............................................13 2.5. References .........................................................................................................13 3. Materials Testing.....................................................................................................15 3.1. Summary of Tests Conducted ...........................................................................15 3.2. Coating optimization and characterization........................................................16 3.2.1. Rationale/Background....................................................................................17 3.2.1.1. HVOF Application..................................................................................17 3.2.1.2. HCAT Coating Optimization and Deposition Philosophy – Fatigue......17 3.2.1.3. Fatigue Cycle Life vs. Fatigue Coating Integrity....................................18 3.2.2. Test methodology...........................................................................................19 3.2.2.1. DOE Methodology..................................................................................19 3.2.2.2. HVOF Optimization................................................................................19 3.2.2.2.1. General...............................................................................................19 3.2.2.3. General Example: CCAD Analysis........................................................20 3.2.3. Test Results....................................................................................................21 3.2.3.1. General Sequence....................................................................................21 3.2.3.2. Northwestern/Generic Protocol at Hill AFB JP 5000 .............................22 3.2.3.2.1. General Test Results..........................................................................22 3.2.3.2.2. General Discussion............................................................................24 3.2.3.3. CCAD DOE 1998...................................................................................25 iii 3.2.3.3.1. General Test Results..........................................................................25 3.2.3.3.2. General Discussion............................................................................28 3.2.3.4. LG DOE at Hitemco: 1998-1999 DJ 2600 System...............................29 3.2.3.4.1. General Discussion............................................................................33 3.2.3.5. Almen Strip and Temperature Measurement Procedures .......................34 3.2.4. Interpretation and Discussion ........................................................................35 3.2.5. Significance....................................................................................................36 3.2.6. Conclusions....................................................................................................36 3.3. Fatigue data.......................................................................................................37 3.3.1. Data Summary...............................................................................................37 3.3.2. Test Rationale................................................................................................37 3.3.3. Specimen Fabrication.....................................................................................40 3.3.3.1. Specimen Geometry and Materials: ........................................................40 3.3.3.2. Specimen preparation..............................................................................41 3.3.4. Coating deposition methodology ...................................................................42 3.3.5. Test methodology...........................................................................................43 3.3.6. Test results.....................................................................................................47 3.3.6.1. 4340 Substrate.........................................................................................47 3.3.6.2. A100 substrate.........................................................................................51 3.3.6.3. 300M substrate........................................................................................54 3.3.7. Coating integrity............................................................................................56 3.3.8. Discussion of trends in fatigue results ...........................................................59 3.3.9. Significance....................................................................................................60 3.3.10. Conclusions....................................................................................................60 3.4. Corrosion data...................................................................................................61 3.4.1. Data summary ................................................................................................61 3.4.2. Pre-JTP atmospheric corrosion testing ..........................................................61 3.4.2.1. Specimen preparation..............................................................................62 3.4.2.2. Experimental Procedures.........................................................................63 3.4.2.3. Results and Discussion............................................................................63 3.4.3. Rationale for JTP testing................................................................................66 3.4.4. Landing gear original JTP testing..................................................................67 3.4.4.1. JTP specimen fabrication and deposition methodology..........................67 iv 3.4.4.2. JTP test methodology..............................................................................68 3.4.4.2.1. Test Description.................................................................................69 3.4.4.3. Test results...............................................................................................73 3.4.4.3.1. 4340 Steel in ASTM B-117...............................................................73 3.4.4.3.2. 300M Steel in B 117..........................................................................75 3.4.4.3.3. 300M Steel in GM 9540 P.................................................................76 3.4.4.3.4. Aermet 100 Steel in B 117 ................................................................76 3.4.4.3.5. Aermet 100 Steel in GM 9540P ........................................................77 3.4.4.3.6. Comparison of performance of WC-Co and WC-CoCr coatings without sealer........................................................................................................77 3.4.5. Additional B117 Corrosion Testing...............................................................85 3.4.5.1. Background .............................................................................................85 3.4.5.2. Specimen Preparation and Coating Deposition.......................................86 3.4.5.3. Results and Discussion............................................................................90 3.4.5.3.1. Protection Ratings..............................................................................90