Patent ID: 7615184
Filing Date: 2009-11-10
Classification: B22F,C04B,C08J,C22C,Y10T

Abstract:
1. A method for making a hollow foam article comprising the steps: a) selecting a polymeric substrate consisting of an open cell foam, said polymeric substrate having exterior surfaces and interior surfaces; b) coating said exterior and interior surfaces of said foam substrate with an aqueous slurry comprising a gel forming binder and inorganic particles, said inorganic particles being at least one member of the group consisting of a ceramic powder, a metal powder, a cermet powder, carbon nanotubes, metal whiskers, ceramic whiskers, or their mixture to form a coated article, said slurry being applied at a temperature above its gelation temperature and at a temperature less than about 60° C., said slurry having a viscosity less than or equal to 0.1 Pa-sec at the application temperature; c) optionally, removing excess slurry from the coated foam article; d) cooling said slurry to a temperature below its gelation temperature; e) substantially drying the coated foam article; f) optionally repeating steps b) through e) one or more times; g) heating the coated article for periods of times, at temperatures and in atmospheres sufficient to vaporize the polymeric substrate forming a green hollow foam article; h) sintering the green hollow foam article in a protective atmosphere under conditions of time and temperatures as are required to cohere the inorganic particles into a unitary hollow foam article having hollow structural members with interior surfaces having essentially the initial form of the vaporized substrate.