Kent E. Coulter

Freestanding foils of nanotube arrays fused with metals

Novel freestanding foils of vertically aligned carbon nanotube arrays (VANTAs) fused with metals are fabricated in a scalable four-step process of (1) VANTA synthesis, (2) deposition of partially infused metal film, (3) removal from growth substrate, and (4) optional deposition of a second metal film on the back side. Mechanical and electrical testing demonstrates excellent contact between the VANTA and the interface-infused metal layers.

Un-supported Palladium Alloy Membranes for the Production of Hydrogen

Thin self-supported permeable membranes of palladium alloys such as Pd60Cu40 have many applications in which hydrogen separation is required. Magnetron sputtering onto selected flexible or non-flexible substrates, for example using a watersoluble release agent or backing, has allowed lift-off and production of high quality films of controllable alloy composition down to 3μm in thickness. The targeted manufacturing process is a low-cost reel-to-reel process that will theoretically meet the targets established by DOE. The results from a recently completed project and some of the remaining problems are discussed.

Preparation of yttria-stabilized zirconia nanoplatelets using vacuum roll coating

Roll-to-roll vacuum coating on moving plastic substrates and the subsequent comminuting of the film into a flake or platelet with microscale lateral and thickness dimensions is an industrially mature technology utilized to produce clean, consistent material with high throughput. In this study, we describe the novel preparation of nanoplatelets by top-down vacuum evaporation of yttria-stabilized zirconium dioxides (YSZ) on a nanoembossed, moveable substrate for the purposes of making nanoplatelets. Microscopy and particle size analysis of the resulting YSZ nanoplatelets revealed that use of the nanoembossed substrate results in significant narrowing of the particle size distribution. However, while the YSZ coatings were conformal and successfully replicated the nanopattern of the underlying substrate, the stress in the film was inadequate to fracture the film into platelets that replicated the nanometer dimensions of the underlying pattern. It was determined that this is due to the inherent fracture toughness of the nanoplatelets and the augmented adhesion forces along the increased length scale of nanoparticle contacts. The nanoplatelets were further reduced in average size and size distribution by post-processing techniques of sonication, ball milling, and centrifugation. The nanoplatelet’s stoichiometry and crystallinity were modified by manipulating the source material, deposition parameters, and post-processing steps.