Corrosion is one of the costliest opponents the U.S. Department of Defense faces, at $20 billion to $23 billion annually.

That figure covers corrosion prevention and maintenance across every aircraft, ship, ground vehicle and piece of infrastructure the military owns—roughly 20% of the department’s annual maintenance budget, or about $55 million per day. The U.S. Air Force alone accounts for $5 billion of it.

For decades, the standard defense against corrosion has been a primer built around hexavalent chromium, a reliable, effective coating. Unfortunately, it leaches into soil and groundwater and is a potential health hazard.

The DOD has long been looking for a replacement. A team at the University of Oklahoma’s Gallogly College of Engineering is trying to deliver one.

Their work is funded through a $4.8 million commitment from the Oklahoma City Air Logistics Complex at Tinker Air Force Base, the depot that maintains the B-1B bomber, the KC-135 transport and the E-3 Sentry, among other active aircraft. The project, now in its second year of four, is led by Gallogly College Dean John Klier as principal investigator, with Brian Grady—OU’s Douglas and Hilda Bourne Chair of Chemical Engineering—and Wilson Merchán-Merchán, a professor in the School of Aerospace and Mechanical Engineering. Gallogly College Special Programs Officer Cliff Wojtalewicz manages the joint effort.

“A chromium-based coating product has been the standard,” Wojtalewicz says. “But it’s not good for the environment, it’s not good for the people who have to apply it to the equipment. So we’re looking for alternative solutions.”

“Our research team has made tremendous progress on our ongoing research efforts to develop novel, chromium-free, organic coatings,” says Klier, who also serves as a professor in OU’s School of Chemical, Biological and Materials Engineering. “The primers we are developing are being designed to provide excellent corrosion protection and adhesion to pretreated aluminum alloys while offering exceptional fluid resistance and outstanding flexibility.”

The goal is an epoxy-based primer that protects pretreated aluminum the way chromium-containing primers do. Several prototype additive systems have been developed. Spraying and testing infrastructure is in place, and formulations are being applied and evaluated.

The tests do not directly involve aircraft. Team members use “coupons,” an industry term for product test strips. They are small pieces of sheet metal, typically three by four inches, coated with one of the variant formulations and placed in a campus laboratory rigged to simulate elements a military aircraft would be exposed to: salinity, humidity, temperature swings and fluid exposure. The team runs what Wojtalewicz calls “extremely aggressive” testing on each coupon-coating candidate.

In the project’s fourth year, the most promising product formulations will move from simulation to a salt-air coastal site, or what the team refers to as a “beach test.”

The stakes scale with the budget. A 1% reduction in the DOD’s corrosion maintenance bill would save taxpayers hundreds of millions of dollars. A safer primer also will mean maintenance line workers won’t be handling hazardous materials.

Something else just as valuable is being built in the OU laboratory alongside primers. Some 10 OU undergraduate and graduate students majoring in chemical and mechanical engineering are gaining professional experience that can be carried into the private business sector. 

“Commercial companies that maintain equipment and infrastructure located all over the world experience similar issues,” Wojtalewicz says. “OU students are working real-world problems, which prepares them for jobs.”

Nadine Samilpa-Sandoval, who is in her final year of a chemical engineering master’s degree, is one example. She has been developing knowledge and skills that will serve her well in a career, Klier says.

“I have built a primer database—a fully automated, AI-powered system that analyzes anticorrosion primer formulation compositions and data,” says Samilpa-Sandoval, a native of Tulsa. 

Wojtalewicz says that by partnering with the DOD, OU also is introducing engineering students to a career field many might not have otherwise considered. 

“We’re exposing them to national security concepts, real-world issues that they may very well deal with,” Wojtalewicz says. “This sort of work matters to the protection of our country.”

The fingerprints of OU students and researchers will be all over the project’s first deliverable: a primer that accomplishes what hexavalent chromium does without the same negative impact on people applying it. If it works and survives testing, the formulation will go back to the Air Force’s anti-corrosion specialists for evaluation and, from there, into a process that could see the primer applied in the flight line at Tinker Air Force Base.

The coupons in the laboratory are small, Wojtalewicz acknowledges. But the aircraft and opportunities they represent are not.

Brian Brus writes for the University of Oklahoma Foundation.