Sintered shaped abrasive grains on basis of alumiunum oxide comprising mineralogical phases consisting of mullite, tialite and/or armalcolite, and baddeleyite and/or srilankite and a method for their production

1. A method for producing sintered abrasive grains, comprising the steps:

preparing a homogeneous dry mixture of 85%-95% by weight alumina (Al 2 O 3 ), 1.0%-10% by weight zircon sand (ZrSiO 4 ), and 0.5%-8.0% by weight ilmenite (FeTiO 3 ), whereby raw-material-based impurities are less than 2% by weight;

adding at least one binder and at least one solvent together with one or more additives selected from the group comprising dispersants, lubricants and plasticizers for obtaining an extrudable mass;

extruding the mass;

cutting the extruded product to shaped abrasive grain precursors; and

sintering the shaped abrasive grain precursors in a temperature range between 1450° C. and 1650° C. to obtain sintered abrasive grains comprising corundum (Al 2 O 3 ), mullite (3Al 2 O 3 *2SiO 2 ), tialite and/or armalcolite (Al 2 TiO 5 /AlFeTiO 5 ) and baddeleyite and/or srilankite (ZrO 2 /Ti 0.75 Zr 0.25 O 2 ), wherein the sintered abrasive grains comprise a weight content of:

Al 2 O 3 between 85% and 95% by weight;

titanium compounds, expressed as TiO 2 , between 0.5% and 5.0% by weight;

silicon compounds, expressed as SiO 2 , between 0.3% and 4.0% by weight;

iron compounds, expressed as Fe 2 O 3 , between 0.4% and 9.0% by weight;

zirconium compounds, expressed as ZrO 2 , between 1.0% und 9.0% by weight; and

raw-material-based impurities of less than 2% by weight.

2. The method according to claim 1 , whereby the ratio by weight percent of zircon sand to ilmenite is from 1:6 to 6:1.

3. Sintered abrasive grains comprising corundum (Al2O3), mullite (3Al2O3*2 SiO2), tialite and/or armalcolite (Al2TiO5/AlFeTiO5) and baddeleyite and/or srilankite (ZrO2/Ti0.75Zr0.25O2), wherein the sintered abrasive grains comprise a weight content of

Al 2 O 3 between 85% and 95% by weight;

titanium compounds, expressed as TiO 2 , between 0.5% und 5.0% by weight;

silicon compounds, expressed as SiO 2 , between 0.3% and 4.0% by weight;

iron compounds, expressed as Fe 2 O 3 , between 0.4% and 9.0% by weight;

zirconium compounds, expressed as ZrO 2 , between 1.0% und 9.0% by weight; and

raw-material-based impurities of less than 2% by weight.

4. Sintered abrasive grains according to claim 3 , whereby the ratio by weight percent of mullite to tialite and/or armalcolite is from 6:1 to 1:6.

5. Sintered abrasive grains according to claim 3 having a density of ≧3.6 g/cm 3 and a hardness HV between 14 and 18 GPa.

6. Sintered abrasive grains according to claim 3 having a MKZ-value of ≦2.0%.

7. Sintered abrasive grains according to claim 6 having a MKZ-value of ≦1.2%.

8. Sintered abrasive grains according to claim 3 , whereby the sintered abrasive grains are rod shaped bodies having a diameter between 0.5 and 5 mm and a length between 1 and 10 mm, wherein the ratio of diameter to length is between 0.2:1.0 and 1.0:1.0.

9. Sintered abrasive grains according to claim 3 , wherein the sintered abrasive grains are manufactured by a method comprising the following steps:

preparing a homogeneous dry mixture of 85%-95% by weight alumina (Al 2 O 3 ), 1.0%-10% by weight zircon sand (ZrSiO 4 ), and 0.5%-8.0% by weight ilmenite (FeTiO 3 ), whereby raw-material-based impurities are less than 2% by weight;

adding at least one binder and at least one solvent together with one or more additives selected from the group comprising dispersants, lubricants and plasticizers for obtaining an extrudable mass;

extruding the mass;

cutting the extruded product to shaped abrasive grain precursors; and

sintering the shaped abrasive grain precursors in a temperature range between 1450° C. and 1650° C.