GLRPPR: Sector Resources: Documents: Hexavalent Chrome Elimination from Hard Chrome Surface Finishing
 
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GLRPPR Sector Resource: Hexavalent Chrome Elimination from Hard Chrome Surface Finishing

Title:
Hexavalent Chrome Elimination from Hard Chrome Surface Finishing

Abstract:
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 will be 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, will 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 {mu}g/m3 to 5 {mu}g/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 will provide 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 will also be discussed.

URL:
https://www.serdp-estcp.org/Tools-and-Training/Webinar-Series/10-01-2015

Source:
U.S. Department of Defense

Resource Type:
Audio/video

Date of Publication:
October 2015

Associated Sectors:

GLRPPR is a member of the Pollution Prevention Resource Exchange, a national network of regional information centers: NEWMOA (Northeast), WRRC (Southeast), GLRPPR (Great Lakes), ZeroWasteNet (Southwest), P2RIC (Plains), Peaks to Prairies (Mountain), WSPPN (Pacific Southwest), PPRC (Northwest).

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