One of the fastest growing market segments in the thermal spray industry is the application of HVOF applied tungsten carbide coatings as a hard chrome replacement on hydraulic cylinder rods.

HVOF applied coatings have proven to be superior to hard chrome with regard to both wear and corrosion resistance.

Thermal Spray Solutions provides hard chrome replacement coatings.

Background
Hard chrome plating is a technique that has been in commercial production for many decades. It is a critical process associated with maintenance activities at all Department of Defense (DOD) depots and shipyards.

Hard chrome plating utilizes chromium in the hexavalent state (hex-Cr), which is a known carcinogen. As a result, the Environmental Protection Agency (EPA) has issued stringent air emission standards for hex-Cr and the Occupational Health and Safety Administration (OSHA) has established permissible exposure limits (PEL) for hex-Cr in the workplace at significantly reduced levels.

As a result, it is estimated that the cost of compliance for hard chrome plating facilities to upgrade their equipment to meet the standards will significantly increase the cost of hard chroming and will result in a number of plating facilities closing down operations.

At the forefront of this issue the Department of Defense has concluded that hard chrome plating will not be feasible at Defense Department depots.

Market Developments
The search for hard chrome alternatives began in the mid 1990’s when the U.S. and Canadian governments established a joint government / industry initiative that led to the creation of the Hard Chrome Alternatives Team (HCAT).

With HVOF coatings already having proved successful in DoD depots, much of the focus of HCAT centered on HVOF applied coatings.

After extensive and exhaustive testing, the conclusion of this study was that HVOF coatings are far superior to chrome plating for wear resistance and also to hard chrome for corrosion resistance. They are being used extensively on a wide variety of components at DoD depots, U.S. Navy shipyards, commercial shipyards supporting DoD contracts, second and third tier government contractors, and Certified thermal spray facilities that support the DoD.

The application of thermal spray coatings as a hard chrome alternative complies with the DoD Green Procurement Policy issued in 2004.

In the commercial marketplace, a number of airlines such as Delta and Lufthansa were also funding studies and testing HVOF applied coatings as a hard chrome replacement with similar results.

One of the significant advantages of using thermal spray coatings as hard chrome alternatives in the commercial and industrial marketplace is the variety of available coating materials. This means that coating materials can be successfully tailored to specific applications in various operating environments where electrolytic hard chrome would not perform well or in fact, may not be considered at all.

Experience
Thermal Spray Solutions has successfully coated hundreds of hydraulic cylinder rods with HVOF applied tungsten carbide coatings for increased wear and corrosion resistance.

Other alternative thermal spray coating materials used in specific applications are chrome carbide, tungsten carbide nickel chrome, tungsten carbide cobalt chrome, stainless steels, metals, chrome oxide, and alumina titania.