This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Evaluation of Alternatives to Electrodeposited Cadmium for Threaded Fastener Applications
Technical Paper
2006-01-3169
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Cadmium (Cd) plating offers good corrosion resistance, lubricity, solderability, adhesion, and ductility, as well as consistent torque-tension and uniform thickness on components with complex geometries. However, the intrinsic Environmental, Health, and Safety issues associated with Cd have driven many users to seek alternatives. Currently, various Cd replacement teams/programs such as the Joint Group on Pollution Prevention (JG-PP)/Boeing, the Joint Cadmium Alternatives Team (JCAT), the Canadian Cadmium Replacement Program (CCRP), and the REFOCUS Program (AEA Technology, European) have been investigating alternatives to Cd plating. Some of the current coatings being considered in the aerospace industry include Zn-Ni alloy plating, electrodeposited aluminum, electroless nickel, nickel composite, and molten salt aluminum manganese (Al-Mn). Each option has its own particular characteristics; however, most experiments have been conducted on aerospace structural panels or components. There is a need to evaluate various alternative coatings for complex geometries such as threaded fasteners.
To this end, Lockheed Martin Aeronautics and Alcoa Fastening Systems have teamed to evaluate Cd alternatives for threaded fasteners used in the inlet of F-16 aircraft. One F-16 manufacturing process generates Cd dust from the fastener heads during sanding. The United States Air Force has funded Lockheed Martin Aeronautics to qualify a replacement for the Cd. The primary fasteners in question are NAS 1580 and NAS 4452 fasteners. Four candidate coatings were selected for evaluation: electroless nickel (EN), electroless nickel composite (EN-PTFE), electrodeposited surface mineralization based zinc-nickel (Zn-Ni), and electroplated aluminum (Al). Stress corrosion, salt spray (fog) tests, torque-tension relationship, locking and breakaway torque measurements, and push-in and interference tests were used to evaluate alternatives to Cd coatings used for corrosion protection and lubricity on threaded parts. For comparison, Cd plated fasteners were tested at equivalent conditions as the controls.
Testing results showed that the surface mineralization based Zn-Ni coating best seems to mimic the overall characteristics of fasteners coated with cadmium. However, no one coating appears to offer the same broad range of properties as Cd plating. Salt spray tests indicated that EN and EN-PTFE exhibited red rust after 96 hours exposure. However, EN-PTFE demonstrated the best coefficient of friction feature, having the least overall torque to achieve the required tension. During torque tension tests, Zn-Ni performed nearly as well as Cd plating. Locking and break-away tests showed that Zn-Ni, EN-PTFE, and Cd nut/bolt sets meet the specification requirements. Al, Zn-Ni, and Cd showed acceptable resistance to stress corrosion up to 400 hours. However, only Al passed the 587 hours consistent load stress corrosion tests. Push-in tests revealed Cd plating required the minimum load to insert fasteners into aluminum structure with interference, followed by Zn-Ni. Furthermore, cross-sectional metallurgical examinations and interference tests were conducted to evaluate coating characteristics and adhesion strength between substrate and coating.
Recommended Content
Authors
Topic
Citation
Zeng, L., Monserratt, E., Haylock, L., Gurrola, R. et al., "Evaluation of Alternatives to Electrodeposited Cadmium for Threaded Fastener Applications," SAE Technical Paper 2006-01-3169, 2006, https://doi.org/10.4271/2006-01-3169.Also In
References
- Baldwin K.R. Smith C.J.E. “Advances in replacements for cadmium plating in Aerospace applications” Trans IMF 74 6 1996 202
- Groshart E. “Finishing in the Green” Metal Finishing Feb 1997 79
- Legg K.O. “Overview of Chromium and Cadmium Alternative Technologies” Surface Modification Technologies XV Sudarshan T.S. Jeandin M. ASM International Materials Park, Ohio IOM Communications Ltd. UK 2002
- Silva L.A.S. sathler L. The corrosion Bahavior of Cadmium, Zinc, Zinc-Nickel & Nickel-phosphorus/Zinc Commercial Coating in Crloride Solutions” Plating & Surface Finishing Dec 2003 38
- Guo Z. Keong K.G. Sha W. “Crystallisation and phase transformation behaviour of electroless nickel phosphorus platings during continuous heating” Journal of Alloys and Compounds 358 2003 112 119
- Rossi S. Chini F. Straffelini G. Bonora P.L. Moschini R. Stampali A. “Corrosion protection properties of electroless Nicklel PTFE, Phosphate/MoS 2 and Bronze/PTFE coatings applied to improve the wear resistance of carbon steel” Surface and Coatings Technology 173 2003 235 242
- Bates R.I. Arnell R.D. “Microstructure of novel corrosion-resistant coatings for steel components by unbalanced magnetron sputtering” Surface and Coatings Technology 89 1997 204 212
- Navinsek B. Panjan P. Milosev I. “PVD coatings as an environmentally clean alternative to electroplating and electroless processes” Surface and Coatings Technology 116-119 1999 476 487
- Fisher J. Fuhr B. “Aluminum plating to replace Cadmium” Advanced Materials and Process 4 1999 27
- Legg K. “Cadmium Replacement Alternatives for the Joint Strike Fighter” December 18 2000
- Heimann N. Simpson G.T. “Surface Mineralization as an Alternative to Cadmium Plating and Hexavalent Chromate Treatment for Corrosion Protection” Navy ISA RUST Conference Louisville, KY 2005
- Heimann N. Simpson G.T. “Surface Mineralization as an Alternative to Cadmium Plating and Hexavalent Chromate Treatment for Corrosion Protection” SAE ComVec Meeting October 2005
- Huang Y.S. Zeng X.T. Hu X.F. Liu F.M. “Corrosion resistance properties of Electroless nickel composite coatings” Electrochimica Acta 49 2004 4313 4319
- Huang Y.S. Zeng X.T. Annergren I. Liu F.M. “Development of electroless NiP-PTFE-SiC composite coating, Surface and Coatings Technology” 167 2003 207 211
- Heimann N.
- JG-PP test report http://www.jgpp.com/projects/cadmium/bisdsjtr/bisdsjtr.pdf
- Endon P.R. “The performance of Electroless Nickel/PTFE Composites” Plating and Surface Finishing Sept. 1988 65 68
- Sisti M. Ruffini A. “Electroless Nickel: Technology, Properties and Applications” http://www.pfonline.com/articles/pfd0507.html
- National Aerospace Standard NASM 25027 specification 16
- Ramalho A. Miranda J.C. “Friction and wear of electroless NiP and NiP + PTFE coatings” Wear 259 2005 828 834
- Jones D.A. Principles and Presentation of Corrosion Second 1996 Prentice hall Upper saddle River, NJ 07458 168 198
- JG-PP test report http://www.jgpp.com/projects/projects_index.html Select Joint Cadmium Alternatives Team
- Bielawski M. “Development of unbalanced magnetron sputtered Al-Mo coatings for cadmium replacement” Surface and Coatings Technology 179 2004 10 17