Hard chrome (Cr⁺⁶) provides hardness, corrosion protection and a low coefficient of friction for aircraft landing gear. However, hard chrome plating baths have to meet strict regulations from both the Occupational Safety and Health Administration (OSHA) and the Environmental Protection Agency (EPA). OSHA may limit Cr⁺⁶ to .05, which will require more equipment and expense for the plater. New high-tech materials may be a better way to handle aircraft parts.

Dear Pat,
Is there an alternative to hard chrome for aircraft landing gear parts that doesn’t compromise performance?
--John

Hi John,
Hard chrome (Cr⁺⁶) provides hardness, corrosion protection and a low coefficient of friction for aircraft landing gear. However, hard chrome plating baths have to meet strict regulations from both the Occupational Safety and Health Administration (OSHA) and the Environmental Protection Agency (EPA). OSHA may limit Cr⁺⁶ to .05, which will require more equipment and expense for the plater. In addition, hard chrome plating baths require the proper ventilation, and the bath makeup must be monitored to make sure the right amount of catalyst is present or no plating will occur.

The Hard Chrome Alternatives Team (HCAT), a bi-national team comprising a U.S. team concentrating on replacing chrome plating in U.S. Department of Defense (DoD) repair depots, and a Canadian team working primarily to replace chrome on commercial and military aircraft landing gear, is working on high velocity oxy-fuel (HVOF) thermal spray as a replacement. Currently landing gear is undergoing validation, and other assemblies will follow.

Meanwhile, nanotechnology is providing other alternatives. PComP™, manufactured by Powdermet Inc., is a low-cost and environmentally friendly nanocomposite substitute for hard chrome. The metal-ceramic composite particles provide an optimum blend of the high wear and hardness associated with nanocrystalline ceramic materials with the ductility and toughness of metal binders. Powdermet’s studies show that nanotechnology is making coatings stronger, lighter and more wear resistant. Andrew Sherman, the company’s president, says, “Nanotechnology is taking the concept of ‘green’ from marketing gimmick to reality.”

Another nanotechnology-based option is nanoPLATE®, manufactured by Integran. These nanostructured metal coatings have properties that reportedly meet or exceed those of hard chrome (wear resistance, corrosion resistance and coeffecient of friction). The company says that the technology produces a fully dense coating without microcracks, excellent corrosion protection (with no nickel underlay), superior ductility, low sliding wear and a low coefficient of friction.

Other coatings designed to replace hard chrome are also under development. These new high-tech materials may be a better way to handle those aircraft parts.


For more information about HCAT, visit www.hcat.org. Powdermet’s website is at www.powdermetinc.com, and Integran’s website is at www.integran.com.


Pat Plater is a regular feature of Finishing Today magazine. Send your questions to kathe@mayer.ldmi.net.