Chromium Electroplating Alternatives
Partnering with HCAT
(4 Active Projects: Actuators, Helicopter Dynamic Components, Landing Gear and Propeller Hubs)

JG-PP is partnering with the HCAT on four projects that are addressing the replacement of hexavalent chromium electroplating. The HCAT is an organization that is principally sponsored by the ESTCP and is comprised of DoD and OEM stakeholders plus technical experts in coatings technology.

 

The purpose of the JG-PP/HCAT program is to reduce or eliminate the use of EHC plating at aircraft manufacturers and at military and commercial aircraft maintenance depots by validating and implementing HVOF thermal sprayed coatings. The replacement of EHC plating with less hazardous materials and/or a less regulated process is a high priority within the DoD. The U.S. EPA regulates EHC plating operation's air emissions and solid and liquid wastes. OSHA regulates personnel safety in EHC operations. Manufacturers use EHC as a wear-resistant and corrosion-resistant coating for a wide variety of mechanical systems, such as turbine engine components and landing gear. DoD depots and commercial repair shops use it even more widely, both for replacing the EHC coating after stripping and inspection of the component, and as an approved repair procedure for worn part dimensional restoration that may or may not have been chrome plated originally.

In general, preliminary testing has shown that the performance of HVOF coatings is superior to chrome in wear, fatigue, and impact resistance, and is at least equal in corrosion resistance. Furthermore, the HVOF deposition process is faster than chrome (typically 1 to 2 hours versus 24 hours, depending on part size and geometry) and HVOF does not cause hydrogen embrittlement (which eliminates embrittlement relief heat treatments). The consequent reduction in process time can make many components significantly cheaper to coat by HVOF than by EHC plating. Even where HVOF is a more expensive process, its improved performance lowers the expected overhaul frequency, reducing the lifetime cost of ownership.

Because EHC plating is widely used for so many different applications, chrome replacement is being addressed in a phased approach and further broken down into specific aircraft components, including:

• Landing gear (including pistons, actuators, and pins)
• Propeller hubs
• Actuators (hydraulic/pneumatic actuators used throughout aircraft)
• Helicopter dynamic components (including gearboxes, rotor heads, and damper components).

The Landing Gear Project is being executed jointly with the Canadian Government and industry under a formal Project Arrangement. There is a seperate Candadian HCAT team that is conducting their own testing and evaluation with the goal of inserting HVOF technology into their landing gear manufacturers. The U. S. and Canadian HCAT teams share all test data to ensure consistency.

By the end of the JG-PP projects, HVOF coatings will be validated for each of these specific classes of components, and the participants will implement the validated alternative. The U.S. Army Aviation and Missile Lifecycle Management Command (AM LCMC) is replacing electrolytic hard chrome with HVOF coating on the main and tail landing gear system of the Blackhawk
(UH-60).