Zirconia sintered body and process for the production thereof

Claim 2

In the production of a partially stabilized zirconia sintered body wherein the tetragonal phase content is sixty-five percent or more, the sintering temperature is 1100° C. to 1400° C. and the grain size is 0.5 μm or less, a process for the production of the sinterable raw material powder used for said production, said process comprising the steps of: (a) suspending a powder of a zirconium compound containing a stabilizing agent into a solution or slurry containing a compound of a transition metal element other than zirconium, the atomic ratio of said other transition metal element to zirconium being in the range of from 0.0001 to 0.01, the zirconium compound being a compound of at least one material selected from the group consisting of oxide, hydroxide, carbonate, and organic acid salts, the stabilizing agent being at least one compound selected from the group consisting of oxide, hydroxide, carbonate and organic acid salts of at least one element selected from the group consisting of Y, Ca, Mg and Ce, in the range of from 1.3 to 2.0 mol parts as the oxide per hundred of the combination of zirconium compound as zirconia and the stabilizing agent as the oxide, and the other transition metal compound being at least one compound selected from the group consisting of oxide, hydroxide, nitrate, carbonate, chloride, organic acid salts, alkoxide and chelate of at least one transition metal selected from the group consisting of Mn, Fe, Co, Ni, Cu and Zn; (b) removing the solvent from the slurry and drying the resultant powder to form a sinterable raw material powder coated with said transition metal compound.

Claim 3

A process as claimed in claim 1 wherein the zirconium compound containing a stabilizing agent is an oxide which is produced by calcining a hydroxide, carbonate, or organic acid salt co-precipitated from an aqueous solution of zirconium oxichloride and chloride of Y, Ca, Mg, or Ce.

Claim 4

A process as claimed in claim 1 wherein the zirconium compound containing a stabilizing agent is a hydroxide, carbonate or organic acid salt co-precipitated from an aqueous solution of zirconium oxichloride and chloride of Y, Ca, Mg or Ce.

Claim 5

A process as claimed in claim 1, wherein the amount of yttrium compound is between 1.3 mol part and 2.0 mol parts as Y 2 O 3 based on the total amount of zirconium compound as ZrO 2 and yttrium compound as Y 2 O 3 .

Claim 6

In the production of an alumina containing partially stabilized zirconia sintered body, wherein the tetragonal phase content is sixty-five percent or more, the sintering temperature is 1100° C. to 1500° C. and the grain size of the partially stabilized zirconia is 2 μm or less and the grain size of the alumina is 4 μm or less, a process for the production of a sinterable raw material powder used for said production, said process comprising the steps of: (a) suspending a powder of a zirconium compound containing a stabilizing agent and a powder of an aluminium compound into a solution or slurry containing a transition metal compound, wherein the transition metal element of said compound is a metal element other than zirconium, the atomic ratio of said other transition metal element to the combination of zirconium and aluminium being in the range of from 0.001 to 0.01, the zirconium compound being at least one compound selected from the group consisting of oxide, hydroxide, carbonate and organic acid salts, the stabilizing agent being at least one compound selected from the group consisting of oxide, hydroxide, carbonate and organic acid salts of at least one element selected from the group consisting of Y, Ca, Mg and Ce in the range of 1.3 to 2.0 mol parts as the oxide per hundred of the combination of zirconium compound as zirconia and the stabilizing agent as the oxide, the aluminium compound being at least on compound selected from the group consisting of oxide, hydroxide, carbonate and organic acid salts, the transition metal compound being at least one compound selected from the group consisting of oxide, hydroxide, nitrate, carbonate, chloride, organic acid salts, alkoxide and chelate of at least on transition metal selected from the group consisting of Mn, Fe, Co, Ni, Cu and Zn, and the powder of the aluminium compound being between 1 to 60 mol parts per hundred of the combination of the powder of aluminium compound and the powder of zirconium compound containing a stabilizing agent by oxide molar base calculation; (b) removing the solvent from the slurry and drying the resultant powder to form said sinterable raw material powder coated with said transition metal compound.

Claim 7

In the production of an alumina containing partially stabilized zirconia sintered body, wherein the tetragonal phase content is sixty-five percent or more, the sintering temperature is 1100° C. to 1500° C. and the grain size of the partially stabilized zirconia is 2 μm or less and the grain size of the alumina is 4 μm or less, a process for the production of a sinterable raw material powder used for said production, said process comprising the steps of: (a) suspending a powder of a zirconium compound containing a stabilizing agent and a powder of an aluminium compound into a solution or slurry containing a transition metal compound, wherein the transition metal element of said compound is a metal element other than zirconium, the atomic ratio of said other transition metal element to the combination of zirconium and aluminium being in the range of from 0.001 to 0.01, the zirconium compound being at least one compound selected from the group consisting of oxide, hydroxide, carbonate and organic acid salts, the stabilizing agent being at least one compound selected from the group consisting of oxide, hydroxide, carbonate and organic acid salts of at least one element selected from the group consisting of Y, Ca, Mg and Ce in the range of 1.3 to 2.0 mol parts as the oxide per hundred of the combination of zirconium compound as zirconia and the stabilizing agent as the oxide, the aluminium compound being at least on compound selected from the group consisting of oxide, hydroxide, carbonate and organic acid salts, the transition metal compound being at least one compound selected from the group consisting of oxide, hydroxide, nitrate, carbonate, chloride, organic acid salts, alkoxide and chelate of at least on transition metal selected from the group consisting of Mn, Fe, Co, Ni, Cu and Zn, and the powder of the aluminium compound being between 1 to 60 mol parts per hundred of the combination of the powder of aluminium compound and the powder of zirconium compound containing a stabilizing agent by oxide molar base calculation; (b) removing the solvent from the slurry and drying the resultant powder to form said sinterable raw material powder coated with said transition metal compound.

Claim 8

A process as claimed in claim 5 wherein the zirconium compound containing a stabilizing agent is an oxide which is produced by calcining a hydroxide, carbonate or organic acid salt co-precipitated from an aqueous solution of zirconium oxichloride and chloride of Y, Ca, Mg or Ce.

Claim 9

A process as claimed in claim 5 wherein the zirconium compound containing a stabilizing agent is hydroxides, carbonates, or organic acid salts, co-precipitated from an aqueous solution of zirconium oxichloride and chloride of Y, Ca, Mg or Ce.