| abstract |
Ultra-low expansion ceramic articles, having average linear coefficients of thermal expansion below about 5.4 x 10<->7/ DEG C over the range from room temperature to 1000 DEG C, are produced by removal of MgO and Al2O3 from cordierite articles by acid leaching to produce ceramic articles having oxide compositions in the range of about 55-75% SiO2, 18-32% Al2O3, and 7-13% MgO which are characterized by the presence of a major amorphous silica-rich phase. |