Claims
- 1. An abrasive grit comprising from about 20 to about 50% by weight of zirconia of which more than 25% by weight of the zirconia present is in tetragonal crystal form; from 1.5 to about 10%, expressed as titanium dioxide, of reduced titania; from 0.03 to about 0.5% total carbon; impurities, if any, in an amount on analysis expressed as the oxides of not more than 3% by weight, including less than 1% SiO.sub.2 ; and a balance of alumina, said abrasive grain being a fused grit.
- 2. An abrasive grit comprising from about 27 to about 35% by weight of zirconia of which more than 25% by weight of the zirconia present is in the tetragonal crystal form; from 1.5 to about 10%, expressed as titanium dioxide, of reduced titania; from 0.03 to about 0.5% total carbon; impurities, if any, in an amount on analysis expressed as the oxides of not more than 3% by weight, including less than 1% SiO.sub.2 ; and a balance of alumina.
- 3. An abrasive grit according to claim 2, containing from about 2.4 to about 5%, expressed as titanium dioxide, of reduced titania.
- 4. An abrasive grit comprising about 31% zirconia, about 4.5%, expressed as titanium dioxide, of reduced titania; from 0.03 to about 0.5% total carbon; impurities, if any, in an amount on analysis expressed as the oxides of not more than 3% by weight, including less than 0.5% SiO.sub.2 ; and a balance of alumina.
- 5. An abrasive grit according to claim 2, containing from about 0.08 to about 0.25% total carbon.
- 6. An abrasive grit according to claim 3, containing from about 0.08 to about 0.25% total carbon.
- 7. An abrasive grit according to any one of claims 1 to 3, comprising less than 0.5% by weight SiO.sub.2.
- 8. A fused abrasive grit material comprising from about 20 to about 50%, by weight of said abrasive grit material, of zirconia, of which at least 25% by weight of said zirconia is in the tetragonal crystal form; from 0.9 to 6.0%, by weight of said abrasive grit material, of titanium, at least some of which is dissolved in said abrasive grit material, said dissolved titanium existing in a form having compounded therewith less oxygen than titania, with the balance of said titanium, undissolved, existing in at least one compound form having less oxygen than titania; from about 0.03 to about 0.5%, by weight said abrasive grit material, of total carbon; and impurities of not more than about 3.0% by weight of said abrasive grit material; the balance of said abrasive grit material being essentially alumina; wherein said abrasive grit material comprises an alumina-zirconia eutectic microstructural phase.
- 9. The invention of claim 8 wherein said alumina-zirconia eutectic microstructural phase is a matrix having embedded therein primary alumina crystals with said matrix containing essentially no primary zirconia crystals.
- 10. The invention of claim 8 wherein said alumina-zirconia eutectic microstructural phase is a matrix having embedded therein primary zirconia crystals with said matrix containing essentially no primary alumina crystals.
- 11. The invention of claim 9 wherein at least a portion of said dissolved titanium is dissolved in said primary alumina crystals.
- 12. The invention of claim 10 wherein said dissolved titanium is essentially dissolved in said alumina-zirconia eutectic microstructural phase.
- 13. The invention of claim 9 wherein said primary alumina crystals vary in size from about 5 microns to about 50 microns.
- 14. The invention of claim 10 wherein said primary zirconia crystals vary in size from about 5 microns to about 50 microns.
- 15. The invention of claim 13 wherein said primary alumina crystals exhibit a dendritic type of oriented structure separated at least in part by said alumina-zirconia eutectic microstructural phase.
- 16. The invention of claim 14 wherein said primary zirconia crystals exhibit a dendritic type of oriented structure separated at least in part by said alumina-zirconia eutectic microstructural phase.
- 17. The invention of claim 15 wherein the portions of said alumina-zirconia eutectic microstructural phase, which separates said dendritic type of oriented structure of said alumina crystals, comprises rods of zirconia having a high degree of orientation.
- 18. The invention of claim 16 wherein the portions of said alumina-zirconia eutectic microstructural phase, which separates said dendritic type of oriented structure of said zirconia crystals, comprises rods of zirconia having a high degree of orientation.
- 19. The invention of claim 8 wherein said material contains from about 27% to about 35%, by weight of said material, of said zirconia.
- 20. The invention of claim 9 wherein said material contains from about 27% to about 35%, by weight of said material, of said zirconia.
- 21. The invention of claim 8 wherein said material contains from about 1.44% to about 3.0%, by weight of said material, of said titanium.
- 22. The invention of claim 9 wherein said material contains from about 1.44% to about 3.0%, by weight of said material, of said titanium.
- 23. The invention of claim 10 wherein said material contains from about 1.44% to about 3.0%, by weight of said material, of said titanium.
- 24. The invention of claim 8 wherein said material contains from about 0.08% to about 0.25%, by weight of said material, of said total carbon.
- 25. The invention of claim 9 wherein said material contains from about 0.08% to about 0.25%, by weight of said material, of said total carbon.
- 26. The invention of claim 10 wherein said material contains from about 0.08% to about 0.25%, by weight of said material, of said total carbon.
- 27. The invention of claim 8 wherein said alumina-zirconia eutectic microstructural phase comprises zirconia rots having a diameter in the range of greater than 0.2 microns to about 0.4 microns.
- 28. The invention of claim 8 wherein said alumina-zirconia eutectic microstructural phase comprises zirconia platelets having a thickness in the range of greater than 0.2 microns to about 0.4 microns.
- 29. The invention of claim 8 wherein said abrasive grit material is in a size range of 120 grit or larger.
- 30. The invention of claim 8 wherein said impurities contain not more than 0.1%, by weight of said abrasive grit material, of soda, not more than 1.0%, by weight of said abrasive grit material, of silica and not more than 1.5%, by weight of said abrasive grit material, of a combination of magnesia, lime and iron oxide.
- 31. A process of producing an abrasive grit material according to claim 8, comprising the steps of:
- a) combining
- 1) from about 40 to about 78.5 parts by weight of alumina, with
- 2) from about 20 to about 50 parts by weight of zirconia;
- b) melting said combined alumina and zirconia;
- c) after melting said combined alumina and zirconia, adding, to said melted alumina and zirconia,
- 3) from 1.5 to about 10 parts by weight of titania; and
- 4) from about 0.6 to about 5 parts by weight of carbon;
- d) after adding said titania and said carbon, heating the combined ingredients under reducing furnace conditions until said titania is melted and reduced by said carbon; and then
- e) casting the melted composition onto a heat sink material in such a manner that solidification of the melt is effected in under three minutes.
- 32. A process according to claim 31, wherein the composition combined contains from about 27 to about 35% zirconia.
- 33. A process according to claim 31, where the composition cast contains from about 2.4 to about 5% titania.
- 34. A process according to claim 33, wherein solidification of the melt is effected under one minute.
- 35. A process according to claim 33, wherein solidification of the melt is effected under twenty seconds.
- 36. A coated abrasive product comprising an abrasive grain as claimed in one of claims 8-12.
- 37. A bonded abrasive product comprising an abrasive grain as claimed in one of claims 8-12.
Priority Claims (1)
Number |
Date |
Country |
Kind |
7938957 |
Nov 1979 |
GBX |
|
CROSS-REFERENCES TO RELATED APPLICATIONS
This is a continuation-in-part of copending application Ser. No. 917,235, filed Oct. 7, 1986, which is a continuation of application Ser. No. 676,594, filed Nov. 30, 1984, which is a continuation of application Ser. No. 477,065, filed Mar. 21, 1983, which is a continuation of application Ser. No. 205,062, filed Nov. 7, 1980, now abandoned.
US Referenced Citations (25)
Foreign Referenced Citations (10)
Number |
Date |
Country |
888762 |
Dec 1971 |
CAX |
924112 |
Apr 1973 |
CAX |
2900007 |
Jul 1979 |
DEX |
35594 |
Oct 1973 |
JPX |
62111 |
May 1979 |
JPX |
99781 |
Aug 1979 |
JPX |
1409112 |
Jun 1972 |
GBX |
1381814 |
Jan 1975 |
GBX |
1392618 |
Apr 1975 |
GBX |
1421174 |
Jan 1976 |
GBX |
Continuations (3)
|
Number |
Date |
Country |
Parent |
676594 |
Nov 1984 |
|
Parent |
477065 |
Mar 1983 |
|
Parent |
205062 |
Nov 1980 |
|
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
917235 |
Oct 1986 |
|