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Title: Silica powders for powder evacuated thermal insulating panel and method

A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2/ g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.
Inventors:
 [1];  [2];  [2];  [1]
  1. (Knoxville, TN)
  2. (Oak Ridge, TN)
Issue Date:
OSTI Identifier:
869773
Assignee:
Martin Marietta Energy Systems, Inc. (Oak Ridge, TN) ORNL
Patent Number(s):
US 5395604
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN
Country of Publication:
United States
Language:
English
Subject:
silica; powders; powder; evacuated; thermal; insulating; panel; method; spherical; porous; particles; median; size; 100; nanometers; diameter; pour; packing; density; cm; external; surface; range; 90; 600; described; prepared; reacting; tetraakyl; silicate; ammonia; water; alcohol; solvent; distilling; solution; reaction; remove; recover; resulting; aqueous; slurry; dried; ball-milled; provide; defined; internal; porosity; nanometer; panels; significantly; r-values; obtainable; previously; silica powder; packing density; porous silica; alcohol solvent; insulating panel; external porosity; external surface; silica particles; aqueous slurry; thermal insulating; powder evacuated; evacuated thermal; silica powders; provide powder; nanometer size; tetraakyl silicate; pour packing; median size; resulting aqueous; particles provide; defined internal; insulating panels; /423/

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