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US 8,999,872 B2Granted
Method for making porous mullite-tialite composites
AssigneeDow Global Technologies LLC
InventorsDaniel Grohol, Mark L. Dreibelbis, Michael T. Malanga
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AssigneeDow Global Technologies LLC
InventorsDaniel Grohol, Mark L. Dreibelbis, Michael T. Malanga
Estimating the term…
Porous composites of acicular mullite and tialite are formed by firing an acicular mullite body in the presence of an oxide of titanium. In some variations of the process, the oxide of titanium is present when the acicular mullite body is formed. In other variations, the oxide of titanium is applied to a previously-formed acicular mullite body. Surprisingly, the composites have coefficients of linear thermal expansion that are intermediate to those of acicular mullite and tialite alone. Some of the tialite is believed to form at grain boundaries and/or points of intersection between acicular mullite needles, rather than merely coating the needles. The presence of the titanium oxide(s) during acicular mullite formation does not significantly affect the ability to produce a highly porous network of mullite needles.
A porous composite ceramic body comprising interspersed and bonded acicular mullite and tialite crystals, wherein the acicular mullite crystals constitute from 25 to 95% by weight of the crystalline ceramic materials in the composite ceramic body, the tialite crystals constitute from 5 to 75% by weight of the crystalline ceramic materials in the ceramic body, the porous composite ceramic body has porosity of 40 to 60 volume percent and other crystalline ceramic materials constitute from 0 to 5% by weight of the crystalline ceramic materials in the composite ceramic body.
A process for forming an acicular mullite-tialite composite body comprising firing an acicular mullite body at a temperature of from 1450 to 1750° C. in the presence of a source of titanium, to produce the acicular mullite-tialite composite body, wherein the acicular mullite-tialite composite body has a porosity of 40 to 60 volume percent.
A process for forming a composite acicular mullite-tialite body comprising the steps of:
Dependencies are inferred from the claim text.