Abstract: Low thermal expansion ceramics of essentially 100 percent cordierite solid solution are prepared by the devitrification of a glass frit compact having the nominal composition in weight percent 16 percent MgO, 30 percent Al.sub.2 O.sub.3, 54 percent SiO.sub.2. These ceramics exhibit adequate density and strength and are useful for example in the fabrication of gas turbine engine components such as rotor vanes and heat exchangers.

Abstract: Synthetic cordierite (2Mg0,2Al.sub. 2 O.sub. 3.5SiO.sub. 2) ceramic bodies exhibiting low thermal expansions are characterized by a microstructure containing less than 10 percent by volume glass and by microcracks of certain size and frequency of occurrence and may be produced, for example, by (1) dry ball milling talc, ball clay and alpha alumina in noncontaminating media, (2) consolidating the mixture to form a green body, (3) heating the green body at a rate of up to 150.degree.C per hour to a temperature within the range of 1350.degree. to 1425.degree.C, (4) holding the body at this temperature for a time of from 1/2 to 10 hours, and (5) cooling the body to below 1,000.degree.C at a rate of up to 150.degree.C per hour. Such bodies possess good to excellent thermal shock resistance, and chemical durability and are useful, for example, as components in gas turbine engines.