Engineers with the U.S. Naval Air Warfare Command — Aircraft Division (NAWCAD) developed a new active aluminum-rich (Al-rich) primer for coating systems.

The Al-rich product is a metalized, sacrificial, chromate-free, anticorrosion primer intended as an alternative for situations where a chromated primer is currently used.

Two Key Components

The technology’s first key component is the use of a specialty aluminum alloy as the pigment inside the primer. The high efficiency of the aluminum alloy composition, combined with aluminum’s low density, allows the coating to be applied at normal aviation thicknesses — thus eliminating weight concerns.

The second component is a proprietary surface treatment applied to the pigment. Because of its ability to protect aluminum electrochemically, the Al-rich primer has excelled at preventing fastener-induced corrosion as well as filiform corrosion. In addition, the Al-rich primer outperformed chromated primers in many of its tests.

Although metal-rich primers have existed for some time, the Navy says there were underlying problems.  First, traditional zinc-rich coatings are too heavy for aviation applications and not effective on aluminum. Second, other metal-rich coatings do not have the longevity of performance in harsh environments.

Novel Aluminum Pigment

“Al-rich is superior based on the novel aluminum pigment that actively overcomes corrosion by electrochemical means,” said NAWCAD materials engineer Craig Matzdorf. “Current coatings rely on chemical inhibitors like chromate, which are less effective at fighting galvanic corrosion. We anticipate that the Al-rich primer will reduce galvanic and other types of corrosion and its effect on the Navy’s cost and availability.”

Up to this point, the primer has been applied to a U.S. Army helicopter, cargo plane, two Coast Guard tail sections, and various pieces of Navy support equipment. For further testing, the Navy needs larger batch sizes, so it has begun licensing the technology to equipped businesses.

Over the next few years, the Navy plans to apply the new primer to larger portions of its assets.

For more information, contact: U.S. Department of Defense, science.dodlive.mil