High density alumina zirconia ceramics and a process for production thereof

Claim 2

A high density alumina-zirconia ceramic body, the formulation of which comprises alumina ranging from 60 mol percent to 99 mol prcent; zirconia, wherein more than 65 percent of said zirconia is in the tetragonal phase, ranging from 1 mol percent to 40 mol percent; and, an oxide of at least one transition metal element selected from the group consisting of Mn, Fe, Co, Ni, Cu, and Zn, in an amount that said transition metal atom to Al and Zr ranges from 0.01 to 1 percent.

Claim 3

A ceramic body as claimed in claim 1, wherein the average grain size of the alumina is less than 3 μm.

Claim 4

A ceramic body as claimed in claim 1, wherein the average grain size of zirconia is less than 1 μm.

Claim 5

A ceramic body as claimed in claim 1, wherein the zirconia is a partially stabilized zirconia in which there is Y 2 O 3 is an amount of less than 3 mol percent as a stabilizing agent.

Claim 6

A process for the production of a high density alumina-zirconia ceramic body, the formulation of which comprises alumina ranging from 60 mol percent to 99 mol percent; zirconia, wherein more than 65 percent of said zirconia is in the tetragonal phase, wanging from 1 mol percent to 40 mol percent and an oxide of at least one transition metal element selected from the group consisting of Mn, Fe, Co, Ni, Cu and Zn in an amount that said transition metal atom to Al and Zr ranges from 0.01 to 1 percent, which comprises the steps of (a) mixing the following (i), (ii), and (iii) (i) alumina powder, or a precursor powder to generate alumina by heat decomposition, (ii) zirconia powder, or a precursor powder to generate zirconia by heat decomposition, and, (iii) a solution or dispersion containing at least one transition metal element selected from the group consisting of Mn, Fe, Co, Ni, Cu, and Zn, (b) removing the solvent from said mixture, (c) drying the resultant mixture to produce a raw material powder, and, (d) shapng and sintering the aforementioned raw material powder.

Claim 7

A process for the production of a high density alumina-zirconia ceramic body, the formulation of which comprises alumina ranging from 60 mol percent to 99 mol percent; zirconia, wherein more than 65 percent of said zirconia is in the tetragonal phase, wanging from 1 mol percent to 40 mol percent and an oxide of at least one transition metal element selected from the group consisting of Mn, Fe, Co, Ni, Cu and Zn in an amount that said transition metal atom to Al and Zr ranges from 0.01 to 1 percent, which comprises the steps of (a) mixing the following (i), (ii), and (iii) (i) alumina powder, or a precursor powder to generate alumina by heat decomposition, (ii) zirconia powder, or a precursor powder to generate zirconia by heat decomposition, and, (iii) a solution or dispersion containing at least one transition metal element selected from the group consisting of Mn, Fe, Co, Ni, Cu, and Zn, (b) removing the solvent from said mixture, (c) drying the resultant mixture to produce a raw material powder, and, (d) shapng and sintering the aforementioned raw material powder.

Claim 8

The process for the production of a ceramic body as claimed in claim 1, wherein the crystal particle size of the zirconia powder is less than 300 Å, the BET specific surface area of the zirconia powder is more than 8 m 2 /g, the crystal particle size of the alumina powder is less than 1 μm and the BET specific surface area of the alumina powder is more than 5 m 2 /g.

Claim 9

A process for the production of a ceramic body as claimed in claim 5, wherein an alumina-zirconia combined powder is used, said powder being produced by calcining the precipitation which is produced by mixing the dispersion of alumina powder and an aqueous solution containing a zirconium salt with a precipitating agent in step (a).