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US 5,077,241 AGranted
Sol gel-derived ceramic bubbles
AssigneeMinnesota Mining and Manufacturing Company
InventorsKyung H. Moh, Harold G. Sowman, Thomas E. Wood
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AssigneeMinnesota Mining and Manufacturing Company
InventorsKyung H. Moh, Harold G. Sowman, Thomas E. Wood
Estimating the term…
Discrete, free-flowing, ceramic microbubbles consist essentially of at least one of a non-oxide component and an oxide component having diameters in the range of 1 to 300 micrometers and each having a wall thickness of less than 10 percent of the diameter of the bubble. In the process of the invention, a sol precursor and a suitable liquid, referred to as a bloating agent, when added to a bubble promoting medium under proper conditions, provide green gelled microbubbles which after firing are ceramic microbubbles having wall thicknesses less than 10 percent of the diameter of the bubbles. The microbubbles are non-vitreous, sol-gel derived, fine microstructured, uniform, hollow, smooth, and are either essentially all oxide or non-oxide or combinations of both.
A method of preparing green microbubbles comprising the steps of:
Free-flowing, discrete ceramic microbubbles consisting essentially of 1) a non-oxide component selected from metal nitrides and metal carbides or 2) said non-oxide component in combination with a metal oxide component, each microbubble having a fine microstructured ceramic wall and a single central gas-filled cavity, said microbubbles having a diameter in the range of 1 to 300 micrometers and a wall thickness of less than 10 percent of the diameter of the microbubbles.
Dependencies are inferred from the claim text.