Preparation of sintered cordierite glass-ceramic bodies

摘要

Disclosed is the preparation of sintered cordierite-based glass-ceramic bodies via a procedure which uses three all natural starting materials which are white sand, kaolin clay and magnesite. These three raw materials, which are preferably sourced from the same geographic area such as Saudi Arabia, are combined in relative amounts which form, upon subsequent mixing and heating, a specific mixture of oxides of silicon, aluminum and magnesium. Upon melting at 1500-1550° C., this combination of raw materials forms transparent brown glass which after solidification by quenching is then crushed and reduced to grains having a median particle size less than 65 microns. These brown glass grains are consolidated, for example by compaction, to form a green body for sintering. Sintering of the green body at temperatures between about 1000° C. and 1375° C. for from 2 to 5 hours produces glass-ceramic bodies containing a polycrystalline material which comprises mostly material of the cordierite crystal structure. Such cordierite-based glass-ceramic bodies have density, microhardness, CTE and dielectric constant properties which make them suitable for use in various technical fields such as cookware, water filtration devices and equipment, and electronics.

主权项

1. A process for preparing a glass-ceramic body from all natural raw materials said process comprising:
a) mixing a combination of natural raw materials consisting of sand, kaolin and magnesite in relative amounts suitable to provide, upon subsequent homogenization and heat treatment, a mixture of oxides comprising from about 50 wt % to 60 wt % of SiO2, from about 25 wt % to 35 wt % of Al2O3, from about 8 wt % to 12 wt % of MgO, from about 2.5 wt % to 3.5 wt % of TiO2, and from about 0.5 to 1.0 wt % of Fe2O3; b) melting the combination of natural raw materials at a temperature of from about 1500° C. to 1550° C. to form glass material and subsequently quenching said glass material; c) crushing said quenched glass material to frit having a median particle diameter of no greater than about 65 microns; d) consolidating the crushed glass fit into a body; e) sintering said body at a temperature of from about 1000° C. to 1375° C. for a sufficient time to devitrify at least a portion of the glass into a polycrystalline material; and f) cooling to provide a sintered glass-ceramic body comprising a polycrystalline phase which is primarily cordierite with a balance of crystalline material comprising traces of Mg2SiO4 having a crystal structure of forsterite, and having a density of about 2.5 to 2.6 g/cm3.