TRANSPARENT POLYCRYSTALLINE BODY WITH HIGH ULTRAVIOLET TRANSMITTANCE, PROCESS FOR MAKING AND APPLICATIONS THEREOF

摘要

A transparent polycrystalline body having high ultraviolet transmissivity is provided. The body is preferably a sintered magnesia-alumina spinel body having a transmittance of at least 85 percent in the wavelength range from 0.4 microns to 0.8 microns and a transmittance at some wavelength in the wave length range between about 0.2 and about 0.4 microns of at least about 85 percent and a porosity of less than about 0.001 percent. The sintered body is produced by a two-step method comprising forming a closed porosity body from a spinel powder and subjecting the closed porosity body to a hot isostatic pressure treatment. The resulting body has a high transmissivity of electromagnetic radiation in the range between about 0.2 microns and about 6 microns, is resistant to abrasion or erosion, does not substantially deteriorate after exposure to ultraviolet light, and has high strength. The sintered body is useful in a variety of applications, including as a dome and window for missiles and launch tubes.