Batch compositions for cordierite ceramics
AssigneeCorning Incorporated
InventorDavid L. Hickman
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Abstract
Ceramic products consisting principally of cordierite and a method for making them are provided, the method employing batches comprising a mineral component and a chemical component, the mineral component comprising clay and talc and the chemical component consisting essentially of a combination of the powdered oxides, hydroxides, or hydrous oxides of magnesium, aluminum and silicon. Ceramics made by extrusion and firing of the batches can exhibit low porosity, high strength and low thermal expansion coefficients.
Claims18
A batch for a ceramic product consisting principally of cordierite which comprises a mineral component and a chemical component, the mineral component comprising clay and talc and the chemical component consisting essentially of a combination of the powdered oxides, hydroxides, or hydrous oxides of magnesium, aluminum and silicon, the batch having an overall oxide composition effective to yield a principal cordierite phase on firing and the chemical component of the batch constituting 5-50% by weight of the batch.
In the method for making a cordierite ceramic product which comprises the steps of compounding a batch containing source materials for silica, alumina and magnesia, shaping the batch into a green article, and firing the green article to convert the batch materials to cordierite ceramic, the improvement wherein:
- the batch comprises a mineral component and a chemical component;
- the mineral component comprises clay, talc and alumina;
- the chemical component consists essentially of the powdered oxides, hydroxides and hydrous oxides of magnesium, aluminum, and silicon;
- and
- the mineral component contributes 50-95% by weight and the chemical component 5-50% by weight of the fired cordierite ceramic.
A ceramic article composed of at least about 90% by weight of cordierite (2MgO.2Al.sub.2 O.sub.3.5SiO.sub.2) which exhibits a modulus of rupture strength of at least 4000 psi, a total porosity not exceeding about 20% by volume, and an average coefficient of thermal expansion on at least one dimensional axis of the article not exceeding about 4.8.times.10.sup.-7 /.degree.C. over the temperature range RT-800.degree. C.
Dependencies are inferred from the claim text.