Coated abrasive product containing fused zirconia grains and method for abrading iron

Abstract

The cutting rate and useful life of conventional resin bonded coated abrasive products in extremely high pressure abrading operations is significantly increased by using abrasive mineral which consists essentially of fused zirconia. Substantial amounts of diluent may be included, e.g., by blending other less effective abrasive grains with fused zirconia grains or by crushing a hardened co-fusion of alumina and zirconia.

What is claimed is: 
     
       1. Coated abrasive sheet material especially suited for formation into endless belts, said sheet material having a durable, flexible woven cloth backing and abrasive grains firmly adherently bonded thereto by a hardened phenol-formaldehyde resin, .Iadd.said grains consisting essentially of a co-fused blend of alumina and zirconia, .Iaddend.at least 10% of the total weight of said grains consisting of fused zirconia, the balance of the total weight of said grains being no harder than fused alumina, whereby at high pressures an endless belt formed from said sheet material abrades, before failure, a significantly greater weight of free carbon-containing iron castings than does a belt of identical construction except for the use of abrasive grains free from .[.fused.]. .Iadd.a co-fused blend of alumina and .Iaddend.zirconia.  .[.2. The product of claim 1 in which the fused zirconia is at least in part unstabilized zirconium oxide..]. .[.3. The product of claim 1 in which the abrasive grains are comprised of fused zirconia and fused alumina..]. .[.4. The product of claim 3 in which the abrasive grains are comprised of at least 40% fused zirconia by weight..].  .[.5. The product of claim 1 in which the abrasive grains consist essentially of fused zirconia and fused alumina..]. .[.6. The product of claim 1 wherein the abrasive grains consist essentially of a co-fused 
     
     
        blend of zirconia and alumina..]. 7. The product of claim .[.6.]. .Iadd.1 .Iaddend.wherein the blend consists of approximately 40% zirconia by 
     
     
        weight. 8. A coated abrasive product having a durable vulcanized fiber backing and abrasive grains firmly adherently bonded thereto by a hardened phenol-formaldehyde resin, .Iadd.said grains consisting essentially of a co-fused blend of alumina and zirconia with .Iaddend.at least 10% of the total weight of said grains consisting of fused zirconia, the balance of the total weight of said grains being no harder than fused alumina, whereby at high pressures said product, before failure, abrades a significantly greater weight of free carbon-containing iron than does a product of identical construction except for the use of abrasive grains free from .[.fused.]. .Iadd.a co-fused blend of alumina and 
     
     
        .Iaddend.zirconia. 9. In the method for abrading an iron alloy workpiece containing free carbon, said method consisting of forcing said workpiece against a supported, rapidly moving coated abrasive medium, comprising a flexible, durable sheet with abrasive grains adherently bonded thereto by a strong hardened synthetic resin, the improvement consisting of using .[.fused zirconia as.]. .Iadd.abrasive grains consisting essentially of a co-fused blend of alumina and zirconia with .Iaddend.at least 10% of the total weight of said abrasive grains, .Iadd.consisting of fused zirconia, .Iaddend.the balance of the total weight of said grains being no harder than fused alumina, and applying a force to said workpiece sufficient to provide a pressure of at least 200 psi.  .[.10. The method of claim 9 
     
     
        wherein the fused zirconia is stabilized..]. 11. The coated abrasive sheet material of claim 1 in the form of an endless belt. .Iadd. 12. The product of claim 1 in which diluent grains are also incorporated. .Iaddend.