UNITED STATES NAVY AND NANOSTRUCTURED COATINGS

As mentioned in a previous post (Sept. 21, 2009), thermal spray nanostructured ceramic coatings were first developed and applied by the United States Navy [1].  The novel coating that was developed at the University of Connecticut for the Office of Naval Research was nanostructured alumina-13wt% titania (n-AT).  This coating presented clear enhancements in wear-resistance, bond strength, and toughness, compared to its conventional coating counterparts. As a result, it was selected to undergo stringent Navy testing, and received MIL STD 1687A qualification for application onto Navy ship assets.

To date, hundreds of components onboard United States Navy ships have been coated with n-AT; however, one application clearly highlights its unique capabilities.  Mine Countermeasure (MCM) ships play a critical role within the Navy.  Since modern mines are not only triggered by collision, but by sound or magnetic signature of a ship, every effort is made to minimize the use of materials which trigger magnetic resonance. Hence, the ships’ shafts, for example, cannot be fabricated from ferrous material. 

Until the arrival of the n-AT coating, the relatively soft nickel aluminum bronze shafts of the MCM ships underwent refurbishment due to significantly reduced service life mainly due to wear.  The shafts of majority of the MCM ships have since been coated with n-AT coating.  Recently, one of the ship sets was removed and evaluated at a Navy shipyard.  After seven years in service, there were no signs of spallation resulting from wear and/or corrosion.  In fact, over 80 % of the coating showed no visible signs of degradation.  It is important to note that a conventional brittle ceramic coating would never have been considered for this application, since the coating and its substrate are subjected to significant torque, bending, and fatigue levels.  The estimated return on investment cost avoidance, based on an improvement of more than three-fold service life with the nanostructured coating, is over $34,000,000 over the remaining life of these components for the fleet of MCMs.

As a result of these and other cost savings to the Navy, the Navy participants on the program (Lawrence T. Kabacoff, A.K. Vasudevan, Robert McCaw and Kenneth Scandell) were awarded ONR's Cheapskate Award for Affordability.  This prestigious award celebrates technological improvements that have had the greatest impact on the future availability of affordable technologies for Naval forces. 

George E. Kim, Ph.D.

F.W. Gartner

Perpetual Technologies, Inc.

email: gkim@perpetualtech.ca