“Nano Cobalt Alloys and Composites as Alternatives for Chromium and Nickel Plating in Repair Operations" by Dr. Jonathan McCrea
Electrodeposited nickel and hard chromium coatings have been extensively used throughout the DoD for the repair and overhaul of damaged components. However, growing concerns over the environmental and health risks associated with nickel and chromium has increased the demand for environmentally-compliant repair technologies. This presentation described the development of an alternative technology using cost-effective electrodeposited nanostructured metals and metal-matrix composites that meets or exceeds the properties and performance of electrodeposited nickel/chromium-based repairs for military applications. Project objectives included 1) optimizing a nanocrystalline cobalt-phosphorus electrodeposition process for repair operations that is based on conventional direct current rectifiers in order to reduce infrastructure costs associated with pulse plating; 2) developing novel nanocomposite coating systems consisting of a nanocrystalline cobalt-phosphorus matrix embedded with second-phase hard particles in order to improve the abrasive wear performance of nanocrystalline cobalt-phosphorus systems; composite coatings will be created by novel in-situ particle formation and deposition of nanoparticles, and co-deposition of suspended particles; and 3) evaluating equipment for brush plating using the nanocomposite material system. The result aimed to be an environmentally compliant, nanostructured alloy with significant performance enhancements in both mechanical properties and corrosion performance relative to incumbent nickel- and chromium-based repairs. Retaining electrodeposition as the principal manufacturing/deposition method minimizes the degree of deviation from current practice, thereby accelerating the adoption of the technology by the defense sector.
"Qualification Testing of Electroformed Nanostructured Cobalt-Alloy Bushings" by Dr. Alan Grieve
An electroformed nanostructured cobalt-alloy was being tested as a cost-effective replacement for copper-beryllium (CuBe) alloys in manufacturing high-strength aircraft bushings as a part of this project. The machining of CuBe presents significant health hazards due to the high toxicity of beryllium. The nanocrystalline alloy is fabricated using a unique electroforming process that favors nucleation of new grains over growth of existing grains, resulting in an ultra-fine grain structure throughout the entire deposit. Nanostructured materials have higher hardness and higher yield strength than conventional materials. The increase in strength of metals with decreasing grain size is described in the Hall-Petch equation. Grain boundaries act as pinning points, impeding further dislocation propagation. The successful execution of this project aimed to reduced use of toxic beryllium-alloys in low-frequency, rotational wear, defense applications. Specific benefits aimed to include: (1) superior mechanical and tribological properties compared to alternative bushing materials resulting in longer life and ability to handle higher loads, (2) better galvanic match with aluminum structures, (3) a near net-shape manufacturing method resulting in very little material waste (high “buy-to-fly” ratio), and (4) the ability to produce bushings on-demand, alleviating delays related to supply issues in critical repair and overhaul situations.
Dr. Jonathan L. McCrea is the Vice President of Technology for Integran Technologies Inc. He has worked with nanostructured materials for over 20 years. His principal areas of scientific expertise are related to: nanostructured alloy development via electrodeposition, microstructure-property relationships of nanocrystalline materials and the adhesion of nanometal coatings to polymer composites as durable/protective coatings for carbon fiber composites, and low frequency electromagnetic interference protection. Jonathon has been the principal investigator for multiple United States (U.S.) Department of Defense-funded programs which provided fundamental research basis for developing environmentally benign nanocrystalline cobalt-alloy coatings for hard chrome alternative, nanocrystalline zinc-nickel coatings for as an alternative for cadmium, and nanostructured copper and cobalt alloys as an alternative to copper beryllium. He has also worked on several Canadian government-sponsored demonstration/validation projects. Jonathon has authored over 30 scientific publications in nanocrystalline materials and is an active member of several professional organizations. He received his bachelor’s degree in Metallurgical and Materials Engineering at Queen’s University and his doctoral degree from the Department of Material Science and Engineering at the University of Toronto.
Dr. Alan Grieve is a chemist working at U.S. Naval Air Systems Command (NAVAIR) in Patuxent River, Maryland. His current research focuses on the development and implementation of inorganic coatings and pre-treatments for metals and methodologies to assess the shelf-life of aircraft sealant materials. Prior to joining NAVAIR, Alan worked for several small technology companies and served as the principal investigator on a number of materials-focused U.S. Small Business Innovation Research programs, such as the application of chemical vapor deposited coatings to ceramic fibers for use in ceramic matrix composite materials and the development of adhesive materials with very high thermal conductivity. He has authored nine peer-reviewed research papers and has co-authored 8 patents. He earned a bachelor's degree in Chemistry from the University of Birmingham and a doctoral degree in Chemistry from the University of Oxford.