Sintered bead based on zirconia and on cerium oxide

1. A sintered bead to serve in microgrinding or microdispersion applications, said bead being obtained by sintering of a mixture comprising a source of zirconia, a source of CeO 2 , and a source of alumina, said bead presenting the following chemical analysis, in percentages by weight and for a total of 100%:

ZrO 2 +HfO 2 : ≧78%

CeO 2 : ≧15%;

Al 2 O 2 : >0.1%;

additive: >0.1% and <0.8%;

additive/Al 2 O 2 between 0.5 and 2; and

impurities: <1%;

the additive being selected from the group consisting of MnO, MnO 2 , Fe 2 O 3 , CuO, Sb 2 O 3 , ZnO, and mixtures thereof.

2. The sintered bead according to claim 1 , wherein the content of alumina (Al 2 O 2 ) is greater than 0.2% in percentage by weight.

3. The sintered bead according to claim 1 , wherein the content of alumina (Al 2 O 3 ) is less than 1% in percentage by weight.

4. The sintered bead according to claim 1 , wherein the content of alumina (Al 2 O 3 ) is greater than 0.2% and less than 1% in percentage by weight.

5. The sintered bead according to claim 1 , wherein the content of said additive is greater than 0.3% in percentage by weight.

6. The sintered bead according to claim 1 , wherein the total content of alumina plus said additive is greater than 0.6% in percentage by weight.

7. The sintered bead according to claim 1 , wherein the ratio between the percentage of the additive and the percentage of the alumina is greater than 0.7 and less than 1.5.

8. The sintered bead according to claim 1 , wherein the ratio between the percentage of the additive and the percentage of the alumina is substantially equal to 1.

9. The sintered bead according to claim 1 , wherein the content of CeO 2 is less than or equal to 20% by weight.

10. The sintered bead according to claim 1 , wherein the content of alumina (Al 2 O 2 ) is greater than 0.2% and less and 1%, in percentage by weight, and wherein the content of said additive is greater than 0.3% and less than 0.8%, in percentage by weight.

11. The sintered bead according to claim 1 , wherein the content of alumina (Al 2 O 3 ) is greater than 0.2% and less and 1%, in percentage by weight, wherein the content of said additive is greater than 0.3%, in percentage by weight.

12. The sintered bead according to claim 1 , wherein the additive is MnO and/or Fe 2 O 3 .

13. The sintered bead according to claim 1 , wherein the additive is selected from the group consisting of from the group consisting of MnO, MnO 2 , Fe 2 O 3 , CuO, and mixtures thereof.

14. The sintered bead according to claim 1 , wherein the sintered bead has a diameter lying in a range of 0.5 mm to 2.5 mm.

15. The sintered bead according to claim 1 , wherein the sintered bead has substantially no zirconia in monoclinic form.

16. A method of fabricating the sintered bead according to claim 1 , comprising:

flowing a suspension through a calibrated orifice to obtain drops, said drops leaving the orifice to fall into a bath of a gelling solution in which they harden after being transformed in a shape that is substantially spherical, the obtained bead being then extracted from the bath, dried and sintered,

wherein the suspension comprises powders of ZrO 2 +HfO 2 , CeO 2 , Al 2 O 3 and, where appropriate, one or more of oxides selected from MnO, MnO 2 , Fe 2 O 3 , CuO, Sb 2 O 3 or ZnO in quantities such that sintering of a drop of said suspension leads to the bead.

17. A grinder for microgrinding and microdispersing pigments, comprising:

the mixture of beads according to claim 1 .

18. The sintered bead according to claim 1 , wherein the bead has a diameter in a range of 0.5 mm to 2.5 mm.

19. The sintered bead according to claim 1 , wherein the bead has a wear rate of 0.49% to 0.57%.

20. The sintered bead according to claim 1 , wherein the bead has a density of 6.173 g/cm 3 to 6.182 g/cm 3 .