Fused aluminum oxide abrasive grain containing reduced titanium oxide

Abstract

A fused abrasive grain, useful for inclusion in coated abrasives and bonded abrasives, consists essentially of alumina; titanium oxide containing from about 0.42 to about 0.84% titaniun, by weight of the abrasive grain, present as a reduced titanium oxide having an average oxidation state lower than in Ti 2 O 3 ; from about 0.05 to about 0.3% by weight carbon; from about 0.02 to about 0.1% by weight Na 2 O; and from 0 to about 0.1% by weight total of calcium and silicon oxides. The grain before roasting has a gain on ignition of from about 0.4 to about 0.7% by weight, and is produced in an electric furnace by fusing high-purity titania, alumina containing Na 2 O as the only significant oxide impurity, and carbon, followed by crushing and roasting the fused grain.

What is claimed is: 
     
       1. A fused abrasive grain which is bluish black in color consisting essentially of: (1) .[.titanium oxide containing.]. from about 0.42 to about 0.84% titanium, by weight of the abrasive grain, .[.said titanium being present as a reduced titanium oxide having an average oxidation state lower than in Ti 2  O 3  .]. .Iadd.wherein said titanium is present in an easily recognizable second phase and in a form which has a low solubility in aluminum oxide.Iaddend.;   (2) from about 0.05 to about 0.3% by weight carbon;   (3) from about 0.02 to about 0.1% by weight Na 2  O;   (4) from 0 to about 0.1% by weight total of calcium and silicon oxides; and   (5) alumina; said abrasive .Iadd.grain .Iaddend.having a gain on ignition in air before roasting at 1300° C., when of a size of about 147 microns and finer, of from about 0.4 to about 0.7% by weight .Iadd.and having improved abrasive properties wherein said fused abrasive grain has been roasted by subjecting the grain to an oxidizing atmosphere at a temperature of from about 1250° C. to about 1450° C. for from about 5 minutes to about 64 hours.Iaddend..   
     
     
       2. A fused abrasive grain according to claim 1, consisting essentially of: (1) .[.titanium oxide containing.]. about 0.72% titanium, by weight of the abrasive grain;   (2) about 0.2% by weight carbon;   (3) about 0.05% by weight Na 2  O; and   (4) about 98.5% by weight alumina; and having a gain on ignition of about 0.5% by weight.   
     
     
       3. A coated abrasive product comprising: (1) a flexible backing;   (2) abrasive grain according to claim 1; and   (3) adhesive bonding said abrasive grain to said backing.   
     
     
       4. A coated abrasive product according to claim 3, wherein the flexible backing is cloth; the adhesive comprises a making coat of phenolic resin comprising a calcium carbonate filler and a size coat of phenolic resin comprising a reactive filler. 
     
     
       5. A coated abrasive product according to claim 4, comprising a base layer of abrasive grain, under said abrasive grain comprising reduced titanium oxide. 
     
     
       6. A bonded abrasive product comprising: (1) abrasive grain according to claim 1; and   (2) a bonding matrix, bonding together the abrasive grain.   
     
     
       7. A bonded abrasive product according to claim 6, wherein the bonding matrix is phenolic resin. 
     
     
       8. A bonded abrasive product according to claim 6, wherein the bonding matrix is vitrified ceramic bond. 
     
     
       9. A bonded abrasive product according to claim 6, in the form of a grinding wheel. .Iadd. 
     
     
       10.  A fused abrasive grain according to claim 1, wherein the grain size is that produced by solidification of a molten mixture in a water cooled steel pan at a depth of from about 2.5 to about 15 cm. .Iaddend. .Iadd. 
     
     
       11.  The abrasive grain of claim 1, wherein the grain size is that produced when a molten mixture of the composition set forth is poured into a water cooled steel pan to a depth of from about 2.5 to about 6 cm. .Iaddend. .Iadd.12. The abrasive grain of claim 1, wherein roasting is from about 5 to about 20 minutes. .Iaddend.