Electrodeposition of Nanocrystalline Cobalt-Phosphorus Coatings as a Hard Chrome Alternative for Use in Aerospace and Defense Applications by Dr. Jonathan McCrea
Electrolytic Hard Chromium plating (EHC) is a critical manufacturing process widely used for applying hard coatings and for general re-build of worn or corroded aircraft components. However, EHC plating baths contain chromium in its hexavalent state which is a known carcinogen. Therefore, the replacement of hard chromium plating in aircraft manufacturing activities and maintenance depots is a high priority for the Department of Defense (DoD).
Nanovate™ CR, a nanocrystalline cobalt-phosphorus alloy, is commercially available as an environmentally compliant alternative to EHC coatings. As an electrodeposition process, Nanovate™ CR is fully compatible with existing EHC infrastructure, but exhibits higher cathodic efficiencies and deposition rates than EHC, thus yielding higher throughput, reduced plant footprint and reduced energy consumption. Further, Nanovate™ CR offers significant performance enhancements over EHC including superior sliding wear, lubricity, corrosion and much improved fatigue properties.
Nanovate™ CR was developed using SERDP and ESTCP funding, and is now covered under US Military Specification (MIL-DTL-32502). ESTCP project WP-200936 investigated Nanovate™ CR through performance testing and demonstration/validation on a number of components from NAVAIR (air vehicle and ground support equipment) and NAVSEA (shipboard machinery components and ground support equipment).
A general overview of the process and properties of nanostructured coatings is presented in comparison to EHC and other conventional materials. A review of the broad areas of application and demonstration/validation programs for nanostructured materials will also be included. The use of the technology for electroforming high strength bushings, investigated as part of SERDP project WP-2137, is also be discussed.
Electrodeposition of Nanocrystalline Cobalt-Phosphorus Alloy Coatings as an Alternative to Hard Chromium Electroplating by Mr. Jack Benfer and Mr. Ruben Prado
The replacement of EHC plating in aircraft maintenance activities in depots is a high priority for the DoD. EHC is a critical process that is used for applying hard coatings to a variety of aircraft components in manufacturing operations and for general re-build of worn or corroded components that have been removed from aircraft during overhaul.
EHC plating baths contain chromium in its hexavalent state, a known carcinogen. Waste generated from plating operations must be disposed of as a hazardous waste, and plating operations must abide by EPA’s emissions standards and OSHA’s permissible exposure limits (PEL). In 2006, OSHA reduced the PEL for hexavalent chrome and all its compounds from 52 µg/m3 to 5 µg/m3. As such, there is tremendous pressure to find an environmentally acceptable alternative to EHC.
Electrodeposited nanocrystalline cobalt-phosphorus (nCoP) coatings have completed initial evaluations under the ESTCP program (WP-200936). This was achieved through performance testing and demonstration/validation on a number of components from NAVAIR (aircraft components and ground support equipment) and NAVSEA (Naval Sea Systems Command) (shipboard machinery components and ground support equipment) with leveraged funding from the Navy Environmental Sustainability Development to Integration (NESDI) Program. nCoP coatings show great potential as an alternative to EHC due to higher cathodic efficiency, higher deposition rates, high hardness, good sliding wear and superior corrosion resistance. This coating is now specified for engineering design using the recently published military specification, MIL-DTL-32502.
This presentation provided a general overview of the process and properties of nCoP coatings compared to those of EHC. The current testing results of the Joint Test Protocol and field insertion of a component according to ESTCP’s demonstration/validation plan is also discussed.
Dr. Jonathan L. McCrea is the Vice President of Research and Development for Integran Technologies, Inc. Dr. McCrea received his Bachelor’s degree in Metallurgical and Materials Engineering at Queen’s University and his Ph.D. from the Department of Material Science and Engineering at the University of Toronto. He has worked in the area of nanostructured materials for over 17 years with a focus on microstructure-property relationships of nanocrystalline materials and the adhesion of nanometal coatings to polymer composites, specifically pertaining to durable/protective coatings for carbon fiber composites and low frequency electromagnetic induction (EMI) protection. Dr. McCrea has been the principal investigator for multiple DoD-funded projects (SERDP WP-1152, WP-1616 and WP-2137) which provided the fundamental research basis for developing environmentally benign nanocrystalline cobalt-alloy coatings for hard chrome alternative, nanocrystalline zinc-nickel coatings for cadmium alternative, and nanostructured copper and cobalt alloys as an alternative to copper beryllium. Dr. McCrea has also led various Canadian Government-sponsored demonstration and validation projects such as Industry Canada’s TPC, SADI and DDSA programs. Dr. McCrea has presented papers at many international conferences and co-authored over 25 scientific publications in the area of nanocrystalline materials. He is an active member of many professional organizations including the Professional Engineers of Ontario (PEO), American Electroplaters and Surface Finishers Society (AESF), SAMPE, SAE and ASM International.
Mr. Jack Benfer is the Senior Corrosion Engineering Technical Expert and Corrosion Control Program Manager for NAVAIR, Jacksonville. Mr. Benfer has over 26 years of NAVAIR and NAVSEA engineering experience. He holds a Bachelor of Science degree in Materials Engineering from Virginia Tech and a Master’s degree in Materials Science and Engineering from the University of Florida. Mr. Benfer is a NAVAIR Associate Fellow, ITC-certified thermographer, and a certified member of the International Association of Corrosion Engineers. He has authored numerous technical engineering reports and is currently published within Vol. 13 of the ASM Handbook. Mr. Benfer provides in-service engineering support to the depot and fleet through his duties within NAVAIR, and supports Research Development Test and Evaluation (RDT&E) and Acquisition workloads through direct program sponsors and in collaboration with the Naval Air Warfare Center. Mr. Benfer served as Principle Investigator for ESTCP projects WP-200407 and WP-200936 for the development of infrared inspection techniques and nano-crystaline cobalt-phosphorus electroplating, with both receiving project of the year awards. Additionally, Mr. Benfer received the Civilian Meritorious Service Award in 2015 for significant contributions to the U.S. Navy.
Ruben Prado is a Senior Inorganic Coatings Chemist currently working in the Materials Engineering Laboratory at the Naval Air Systems Command, Naval Air Depot, Jacksonville, FL. He is the subject matter expert in electroplating and surface finishing particularly dealing in corrosion and wear coatings on ferrous and non-ferrous alloys in support of P-3, EA-6B, F/A-18, J-52, T-45 and various other programs. He has dedicated over 28 years of professional service to the DoD in surface engineering that encompasses 8 years with the Air Force at Kelly AFB as an Industrial Chemist and over 20 years with NAVAIR as a Process Control and Inorganic Coatings Chemist within the Corrosion Engineering Competency (22.214.171.124) for Materials Engineering. Mr. Prado also provides local training in the area of Aluminum Anodizing for artisans requiring Special Skill Certification, and is continuously involved in process improvements and pollution prevention efforts within NAVAIR. Mr. Prado has also been involved in numerous projects dealing with alternative coatings and improved metal finishing processes supporting the F-15, F-16, C-130 and C-5 programs and has received several awards for his contribution towards process advancements including development of a computer program for optimizing solution analysis and control of finishing operations. His expertise and leadership has resulted in NAVAIR authorization and implementation of advanced anodizing technology across the Navy Fleet Readiness Centers. Mr. Prado graduated from the University of Central Florida with a Bachelor’s degree in Chemistry in 1987. In 1997, he received his certification as an Electroplater-Finisher from the American Electroplaters and Surface Finishing Society and was recognized as a NAVAIR Associate Fellow in 2011.