Coating of Highly Porous Fiber Matrices by Atomic Layer Deposition

The potential of atomic layer deposition (ALD) in the coating of highly porous, 0.5 mm thick, metal fiber matrices is explored. Three different reactor types are compared for ALD of Al2O3 thin films from trimethylaluminum and water. Both an evacuation-type and a flow-type process are successful in forming conformal Al2O3 coatings on the fibers. The coatings are able to protect the fibers against electrochemical corrosion and thermal oxidation. In addition, a metallic Ir thin film is deposited by ALD on one of the Al2O3-coated fiber matrices. This kind of a structure could be used, for example, as a catalytic filter.