Oysters Used for Developing Pearl-Like Aircraft Coating Published June 18, 2008 By Molly Lachance, AFOSR/PIP (Anadarko/CIBER) Air Force Office of Scientific Research ARLINGTON, Va. -- AFRL is funding University of Dayton Research Institute (UDRI) scientists who are conducting biomimetic research that could lead to new lightweight, durable aircraft coatings. UDRI senior research scientists Mr. Doug Hansen and Mrs. Karolyn Hansen are investigating oyster shell and pearl formation processes. By manipulating these naturally occurring phenomena, the two are working towards a method for depositing pearl-like coatings onto various metal surfaces in order to protect against impact and corrosion damage. This project is significant because deposition of the biologically derived ceramic coatings does not involve the high-temperature, high-pressure environment required by existing ceramic deposition methods. The Air Force currently uses protective ceramic aircraft coatings for various purposes; therefore, a nonhazardous process for creating ceramics at room temperature and pressure would provide an interesting, potentially better, alternative to current methods. The UDRI scientists are building on the recent discovery that oysters use blood cells to deposit the crystals that subsequently form shell and pearl. The researchers have targeted these cells, manipulating them to deposit crystals on a variety of metal surfaces in an ordered manner that ultimately produces a multilayer ceramic coating. The goal of the program is to understand the process(es) by which the oyster cells first form these crystals and then deposit them into layers. The scientists hope to achieve a high level of control over the resultant ceramic coating's thickness and placement on materials requiring strong but lightweight protection. In the laboratory environment, live oysters demonstrate ceramic deposition both inside and outside of their shell. Small pieces of metal inserted into the oysters triggers the formation of pearl. Meanwhile, blood cells extracted from the oysters and subsequently placed on metal behave as though they are growing a shell on the metal surface. The scientists were able to deposit multilayer coatings on four different metal surfaces: two aircraft aluminum alloys and two biomedical alloys. They are currently working to characterize the biomimetic coatings in terms of corrosion resistance, strength, and adhesion. Further, they are developing methods for directing the application of ceramic films at specific sites on metal surfaces. This research could generate a better understanding of how biological systems can formulate ceramic coatings and films. Such knowledge could facilitate the development of synthetic processes for depositing ceramic films and coatings without the necessity for high-temperature and high-pressure conditions.