Compatibility of Unsupported Pyrolytic-Carbon Coated Uranium Dicarbide Particles With Water Vapor

Abstract

Five batches of pyrolytic-carbon coated uranium carbide particles were exposed to partial pressures of water vapor ranging from 20 to 635 mm Hg at temperatures of 700 to ll00°C. All batches of coated particles were prepared by Minnesota Mining and Manufacturing Company, had laminar type of coating, and contained cores consisting principally of uranium dicarbide. The rate of reaction of the pyrolytic-carbon coatings with water vapor was determined,from weight losses. The extent of failure of the coatings during exposure was established by microscopic examination and leaching of the particles with 8M HN0 3 • Differences in the protectiveness of coatings present on the various batches of particles are attributable, at least in part, to two types of attack by water vapor, a localized or pitting type and a more general type. Rapid failure of the coatings is indicated at 1100°C. The coatings on some batches of particles remained protective at temperatures of 800 to l000°C. I.