Navy Tech Revolutionizes Metals Industry


A Navy-developed technology could be a game changer for the metalcoatings industry.

The technology is a solution of trivalent chromium sulfate and other additives that reacts with metal surfaces to form a protective undercoat for paint or other coating materials.

The liquid chemical solution is applied to aluminum, zinc, and other substrates to minimize corrosion and provide an improved bonding surface for paints. The substrates are treated with an acidic aqueous solution containing trivalent chromium salt, an alkali metal hexafluorozirconate, and a thickening agent.

Developed by personnel at the Naval Air Warfare Center Aircraft Division in Patuxent River, Maryland, the technology will reduce or replace the ubiquitous use of hexavalent chromium, a known environmental hazard and carcinogen banned in some nations.

In addition to being corrosioninhibitive and adhesion-enhancing, trivalent chromium processes (TCP) are chemically resistant, weather-resistant, flexible at low temperatures, easy to apply, and price-competitive. The technology meets the more demanding EPA and OSHA requirements recently implemented in response to concerns over use of the highly toxic hexavalent chromium.

TCP is the first protective chromium-based metal finishing coating to satisfy military specifications that is both highly effective and environmentally benign.

From bicycles to military aircraft, from metal fasteners to window frames, aluminumand zinc-containing products are used daily throughout the United States and the world. These metals require a protective coating, called a conversion coating, to prevent corrosion and enhance adhesion to their slick surfaces by paint or other coatings.

For more than 50 years, this conversion coating traditionally contained hexavalent chromium, now known to be highly toxic, carcinogenic, and thus hazardous to both humans and the environment.

The U.S. military recently mandated that replacement technologies be used on its aircraft and vessels. The new TCP processes, utilizing nontoxic trivalent chromium instead of hazardous hexavalent chromium, were developed at the Navy laboratory in response to Department of Defense needs.

Not only does TCP fully address government expectations, it will radically change industrywide standards for treating aluminum and other metals. Examples of military usage include improved protection for surfaces of Navy aircraft, which are exposed to corrosive seawater environments, yet require a lightweight coating. Aircraft operating from non-nuclear-powered carriers also are exposed to sulfur dioxide stack emissions and thus require additional anti-corrosion capability. The degrading effects of corrosion increasingly threaten aging commercial airliners as limited airline resources restrict replacing aircraft. Corrosion prevention and weather resistance provided by self-priming topcoats made possible by TCP technology thus will become more important to our present-day airline industry.

The greatest benefit of TCP technology, however, is industrial and military compliance with environmental regulations and the resultant enhancement of public health. Both tangible financial benefits and nontangible environmental benefits have already been realized as a result of the five current licenses.

The Navy’s royalties through 2007 were more than $500,000, in addition to more than $100,000 in initial payments.

Commercial products based on the new TCP technology already are available to a wide variety of consumers. Other products stemming from the five licenses granted in 2004 are now entering the marketplace.

By the end of 2007, the TCP licensees combined sales of TCP-based products to users such as General Dynamics, BAE Systems, Northrop Grumman, Lockheed, and Boeing totaled more than $9 million.