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US 5,183,610 AGranted
Alumina-zirconia ceramic
AssigneeCooper Indusries, Inc.
InventorsTerrence K. Brog, William R. Manning
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AssigneeCooper Indusries, Inc.
InventorsTerrence K. Brog, William R. Manning
Estimating the term…
A method for producing a ceramic is disclosed. The method involves comminuting a batch composed of from 6 to 95 percent of particulate ZrO.sub.2 and from 5 to 94 percent of particulate Al.sub.2 O.sub.3. A part of the particulate ZrO.sub.2 is in a metastable tetragonal crystal structure, for example, as a consequence of 3.sup.m/o of Y.sub.2 O.sub.3 dissolved therein and a part has a monoclinic crystal structure. The comminuted batch is compacted into a shape, and the shape is fired. The degree of comminution of the batch, the firing conditions and the proportions of stabilized and monoclinic ZrO.sub.2 in the batch are controlled to produce a dense, gas impervious ceramic which contains both metastable tatragonal and monoclinic ZrO.sub.2, and in such proportions that the ceramic has improved strength by comparison with an otherwise identical ceramic wherein all of the ZrO.sub.2 is in either a metastable tetragonal or a monoclinic crystal structure. Also disclosed is a method where the particulate alumina can be an alumina-chromia solid solution containing up to 50.sup.m/o of chromia. In another embodiment, a ceramic article is disclosed. The article is composed of from 6 to 95 percent of particulate ZrO.sub.2, from 5 to 94 percent of particulate Al.sub.2 O.sub.3, from 1/4 to 33/4 percent of MnO.sub.2 and from 1/4 to 33/4 percent of TiO.sub.2 .
A method for producing a ceramic which consists essentially of formulating a batch composed of from 6 to 95 percent of particulate ZrO.sub.2 and from 5 to 94 percent of particulate Al.sub.2 O.sub.3 from particulate Al.sub.2 O.sub.3, particulate ZrO.sub.2 is in a tetragonal crystal structure as a consequence of an oxide dissolved therein to promote retention of the metastable tetragonal crystal structure and particulate ZrO.sub.2 which has a monoclinic crystal structure, comminuting the batch, compacting the comminuted batch into a shape, firing the shape, and controlling the degree of comminution of the batch, the firing conditions and the proportions of oxide and of tetragonal and monoclinic ZrO.sub.2 in the batch to produce a dense, gas impervious ceramic which contains both metastable tetragonal and monoclinic ZrO.sub.2, and in such proportions that the ceramic has a strength, as indicated by the modulus of rupture, at least 5 percent greater than that of the stronger of two otherwise identical ceramics, one wherein all of the ZrO.sub.2 in the batch is in a metastable tetragonal and one wherein all of the ZrO.sub.2 in the batch is in a monoclinic crystal structure.
A method for producing a ceramic which consists essentially of formulating a batch composed of from 6 to 95 percent of particulate ZrO.sub.2 and from 5 to 94 percent of particulate Al.sub.2 O.sub.3 containing up to 50 m/o Cr.sub.2 O.sub.3 dissolved therein in solid solution from particulate Al.sub.2 O.sub.3 containing up to 50 m/o Cr.sub.2 O.sub.3 dissolved therein in solid solution, particulate ZrO.sub.2 is in a tetragonal crystal structure as a consequence of an oxide dissolved therein to promote retention of the metastable tetragonal crystal structure and particulate ZrO.sub.2 which has a monoclinic crystal structure, comminuting the batch, compacting the comminuted batch into a shape, firing the shape, and controlling the degree of comminution of the batch, the firing conditions and the proportions of oxide and of tetragonal and monoclinic ZrO.sub.2 in the batch to produce a dense, gas impervious ceramic which contains both metastable tetragonal and monoclinic ZrO.sub.2, and in such proportions that the ceramic has a strength, as indicated by the modulus of rupture, at least 5 percent greater than that of the stronger of two otherwise identical ceramics, one wherein all of the ZrO.sub.2 in the batch is in a metastable tetragonal and one wherein all of the ZrO.sub.2 in the batch is in a monoclinic crystal structure.
Dependencies are inferred from the claim text.