Patent ID: 6300263
Filing Date: 2001-10-09
Classification: C03C

Abstract:
A method of making a glass ceramic article, the method comprising:a) providing a glass having a glass compositional formula expressed in terms of moles of oxides selected from the group consisting of a first glass compositional formula of 2MgO+2Al.sub.2 O.sub.3 +5SiO.sub.2 and a second glass compositional formula of (x/2)A.sub.2 O+yBO+2MgO+Al.sub.2 O.sub.3 +(5-x-2y)SiO.sub.2, wherein, when the glass is of the second formula,A is selected from the group consisting of sodium and potassium,B is selected from the group consisting of strontium and barium;and the sum of x and y is at least about 0.01;b) melting and quenching said glass;c) crushing said glass to a frit having a median particle diameter of no greater than about 150 micrometers;d) consolidating the crushed glass frit into a body;e) sintering the body for a sufficient time and temperature to devitrify the glass into a predominately cordierite phase of cordierite crystals or aggregates of near-parallel crystallites and to coarsen the size of the cordierite crystals or aggregates of near-parallel crystallites to yield microcracks in the subsequently cooled body; andf) cooling to yield a sintered body wherein when the glass is of the first glass compositional formula, the average size of the cordierite crystals or aggregates of near-parallel cordierite crystallites is less than about 70 micrometers, and the mean coefficient of thermal expansion from 22.degree. C. to 800.degree. C. is less than about 9.times.10.sup.-7 /.degree. C., and when the glass is of the second glass compositional formula, the mean coefficient of thermal expansion from 22.degree. C. to 800.degree. C. is not more than about 14.times.10.sup.-7 /.degree. C.