Patent ID: 8119057
Filing Date: 2012-02-21
Classification: C04B

Abstract:
1. A method for synthesizing a dense, crack-free bulk ceramic structure to replace metal or metallic structures consisting of the steps of: selecting an open cell material with an open cell size in a range between 1 mm and approximately 3 mm in diameter to function as a sacrificial mold; cutting the open cell material into a desired shape; selecting a liquid polymeric ceramic precursor from the group consisting of polysilazane, polysilane, polysiloxane and polymethylcarbosilane; adding approximately 1 weight % polymerization initiator to the liquid polymeric ceramic precursor to form mixture (I); saturating the open cell material with the mixture (I) of polymerization initiator and liquid polymeric ceramic precursor selected from at least one of polysilazane, polysilane, polysiloxane and polymethylcarbosilane; curing the open cell material saturated with the ceramic precursor and polymerization iniator in an oven under nitrogen atmosphere at 150° C. to form a dense, solid, body of material that can be converted into a ceramic by pyrolysis and is referred to as a ceramic green body; shaping the solid ceramic green body into a bulk structure with at least one of a lathe and a laser; and pyrolizing the shaped green body, in an oxygen-free atmosphere at a temperature lower than the thermal decomposition temperature of the ceramic precursor, for a period of time to leave a channel network that allows the gaseous products from the pyrolysis of the ceramic precursor to escape without building up pressure which would cause cracks, thereby thermally decomposing the sacrificial mold, and forming a dense, crack-free bulk ceramic structure wherein the density of the final ceramic product is between approximately 91% to approximately 98% of theoretical maximum density thereby providing a dense, crack-free ceramic structure suitable for use in temperature and pressure conditions reserved for use of metal or metallic components.