Thin Thermal-Insulation Blankets for Very High Temperatures

Thermal-insulation blankets of a proposed type would be exceptionally thin and would endure temperatures up to 2,100 C. These blankets were originally intended to protect components of the NASA Solar Probe spacecraft against radiant heating at its planned closest approach to the Sun (a distance of 4 solar radii). These blankets could also be used on Earth to provide thermal protection in special applications (especially in vacuum chambers) for which conventional thermal-insulation blankets would be too thick or would not perform adequately. A blanket according to the proposal (see figure) would be made of molybdenum, titanium nitride, and carbon- carbon composite mesh, which melt at temperatures of 2,610, 2,930, and 2,130 C, respectively. The emittance of molybdenum is 0.24, while that of titanium nitride is 0.03. Carbon-carbon composite mesh is a thermal insulator. Typically, the blanket would include 0.25-mil (.0.00635-mm)-thick hot-side and cold-side cover layers of molybdenum. Titanium nitride would be vapor-deposited on both surfaces of each cover layer. Between the cover layers there would be 10 inner layers of 0.15-mil (.0.0038-mm)-thick molybdenum with vapor-deposited titanium nitride on both sides of each layer. The thickness of each titanium nitride coat would be about 1,000 A. The cover and inner layers would be interspersed with 0.25-mil (0.00635-mm)-thick layers of carbon-carbon composite mesh. The blanket would have total thickness of 4.75 mils (approximately equal to 0.121 mm) and an areal mass density of 0.7 kilograms per square meter. One could, of course, increase the thermal- insulation capability of the blanket by increasing number of inner layers (thereby unavoidably increasing the total thickness and mass density).