Fabrication of ultra low thermal expansion cordierite structures

Abstract

Disclosed is sintered ceramic article that exhibits a primary crystalline phase of cordierite and analytical oxide composition, in weight percent, of 49-53% SiO2, 33-38% Al2O3, 12-16% MgO and exhibits a coefficient of thermal expansion no greater than about 4.0×10−7/° C. over the temperature range of about 25° C. to about 800° C. and a transverse-I ratio of not less than about 0.92. Also disclosed is a method for producing a sintered cordierite ceramic article involving preparing a plasticizable raw material, comprising a magnesium source, a SiO2-forming source and an additional component of either: (a) a clay-free, Al2O3-forming source having a surface area of greater than about 5 m2/g; or, (b) a clay and Al2O3-forming source combination wherein the clay comprises no greater than about 30%, by weight, of the total inorganic mixture, and the Al2O3-forming source exhibits a surface area of greater than about 40 m2/g. The mixture is formed into a green body substrate of the desired configuration and subsequently dried and fired for a time and at temperature sufficient to form a structure having the aforementioned CTE and I-ratio properties.

Dependencies are inferred from the claim text.