Improvement of Metal, Oxide, & Carbon Nanomaterials via Thin Film Coatings and Advanced Microscopic Characterization of Mesoporous Materials

Thin films were deposited on metal, oxide, and carbon nanomaterials via chemical deposition techniques. Experiments were done in a methodical manor in order to obtain desired thickness and morphology of these coatings. Advanced characterization methods were employed on these and colleague produced catalyst materials in order to answer complex questions about their chemical make-up. Electroless deposition of aluminum using room temperature ionic liquids and liquid reducing agents is extremely water sensitive and has only been successful in glove boxes with deposition on copper or glass substrates. We have successfully brought the deposition out of the glove box using Schlenk techniques. We also have reported the first electroless aluminum deposition onto a nickel nanowire substrate. Results indicated a smooth and pure aluminum coating with thin surface oxidation on the nanowires. Metal organic chemical vapor deposition was used to deposit zinc oxide for use as a ceramic matrix composite interphase. ZnO coatings (400-500 nm) were deposited on 3M Nextel™ 610 fabric by thermal decomposition of zinc acetate dihydrate in a low pressure hot wall CVD reactor. An α-alumina matrix was applied to the 8 ply fabric lay up for a total CMC porosity of 30% with 32% fiber volume. Flexural strength of the Oxide-Oxide CMC could be increased up to 30% upon addition of this oxide interphase with corresponding toughening mechanisms. Atmospheric pressure chemical vapor deposition was used to deposit silicon onto ceramic fibers. Silicon was deposited in various geometries including spheres, rods, and wires. Silica was often found on the surface of the fibers after deposition in the form of a thin film (50-600 nm). Deposition conditions were varied based on temperature, flow rate, total flow, tube size, and substrate. The results indicated silica formation on the surface when deposition of silicon was attempted because of oxygen present in the ceramic fiber. Mesoporous manganese oxides or University of Connecticut (UCT) materials were analyzed using advanced electron microscopy techniques in order to determine: dopant distribution, core/shell structure formation, and crystalline phases present. A traditional Focused Ion Beam (FIB) sample preparation method for transmission electron microscope (TEM) analysis was modified in order to successfully prepare these mesoporous powders to electron transparency. This FIB/TEM method applied to these materials will allow solid confirmation of their intricacies