Major corrosion issues faced by Amphibious Assault Vehicles (AAVs) in the United States Marine Corps could be solved with polyurea.
As the U.S. Marine Corps look to extend the AAV, Dr Mike Roland and Dr Ray Gamache of the U.S Naval Research Laboratory (NRL) have led a research project into how best to protect and extend the life of these armoured vehicles.
"Innovative sustainment concepts, like those NRL is investigating, enable us to avoid the cost of new design, development and production of new components," says Tim Bergland of the USMC Advanced Amphibious Assault (AAA) office.
Since the 1990's the U.S. Marine Corps have been using a bolted-on armour to protect their AAVs. This armour is a laminate of high hard steel, rubber and soft steel layer in the back. The issue is this armour gets corroded in extreme conditions - including exposure to salt water.
The corrosion starts at cracks in the paint, which occur due to the expansion of the different layers within the laminate - which expand and contract independently due to environmental changes.
The NRL suggests that polyurea would better protect the armour from corrosion by expanding and contracting with it, rather than cracking as paint does. Furthermore polyurea demonstrated resistance to bullets and blast fragments by taking kinetic energy from the bullet.
By recreating the unique corrosion issues of the Amphibious Assault Vehicles in a lab, the team were concluded that polyurea was much better at protecting the armour against corrosion than paint.
"We solved the corrosion problem," says Dr Mike Roland of the NRL. "And with a negligible increase in weight, we also provided a higher payload capacity and the potential for better ballistic protection."
“In conventional materials, you can have something that’s really stiff but doesn’t stretch much; or you can have something really soft, like silly putty, and it stretches a lot,” says Dr Gamache. “Polyureas, they can stretch to 10 times their original length, but the force it takes to do that is enormous—so you get toughness, the best of both worlds.”
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