Kira N. Shulman, David J. Ross, Victor P. Siller, Daniel J. Rodriguez, Los Alamos National Laboratory, Los Alamos, NM
Thick metal coatings on glass microspheres are developed in a custom magnetron sputtering system built with a vibrating stage assembly to induce constant motion in the microspheres throughout the deposition process. Tungsten and copper were successfully deposited onto 0.5 gram of hollow glass microspheres and 10 grams of solid glass microspheres, respectively. Scanning electron microscopy (SEM) micrographs were utilized to measure coating thicknesses on over 100 microspheres for each completed deposition run. The tungsten-coated microspheres developed a coating thickness distribution of 200-900 nm with a mean coating thickness of 440 nm. The copper-coated microspheres developed a coating thickness distribution of 150-2750 nm with a mean coating thickness of 970 nm. Molded nylon pucks with varying weight percentages of these copper-coated microspheres were developed to test the potential thermal conductivity of this material. While this work demonstrates the success of this method on a laboratory-scale, efforts to develop a larger system capable of producing much higher yield are currently underway.