Claims
- 1. A method of producing a chemically hardened abrasive body which comprises:
- closely packing finely divided discrete relatively fine refractory oxide particles, at least the surface of said particles consists of a refractory oxide of at least one metallic element having a vitrification temperature in excess of 600.degree. F., and including a substantial amount of relatively coarse abrasive grain to form a porous structure;
- impregnating said porous structure with a solution of an inorganic chromium compound capable of being converted to an oxide on being heated to a temperature below the vitrification temperature of said refractory particles and grain;
- drying and curing said impregnated structure by heating same to a temperature below the vitrification and sinter temperatures of the particles and grain but sufficient to convert the chromium compound to an oxide; and,
- repeating the impregnation and heat curing steps at least once to harden and densify the structure.
- 2. The method of claim 1 wherein at least the surface of the particles is selected from the group of inorganic refractories consisting of oxides of aluminum, barium, beryllium, calcium, cerium, chromium, cobalt, copper, gallium harnium, iron, lanthanum, magnesium, manganese, molybdenum, nickel, niobium, silicon, tantalum, thorium, tin, titanium, tungsten, uranium, vanadium, yttrium, zinc, zirconium, and mixtures thereof.
- 3. The method of claim 1 wherein the solution is chromic acid.
- 4. The method of claim 1 which includes as a last step the impregnation of the hardened abrasive structure with phosphoric acid and heating and curing said structure by raising the temperature thereof to at least about 600.degree. F., but below the vitrification and sinter temperature of the refractory particles and grain in increments over a period of time sufficient to completely dry and harden the structure.
- 5. The method of claim 1 wherein a clay or inorganic chromium compound binder is mixed with the finely divided particles prior to forming the structure which serves to hold the particles together during the impregnation and cure cycles.
- 6. The method of claim 1 wherein the abrasive grain is selected from the group of abrasive grains consisting of chromia, tin oxide, titania, aluminum oxide, black silicon carbide, green silicon carbide, bauxite, silicic acid, iron oxide, diamonds and mixtures thereof.
- 7. A method of producing a chemically hardened abrasive body which comprises:
- closely packing finely divided discrete relatively fine refractory particles having a vitrification temperature in excess of 600.degree. F. and including a substantial amount of relatively coarse abrasive grain to form a porous structure;
- impregnating said porous structure with a solution of an inorganic chromium compound capable of being converted to an oxide on being heated to a temperature below the vitrification temperature of refractory particles and grain;
- drying and curing said impregnated structure by heating same to a temperature below the vitrification and sinter temperature of the particles and grain but sufficient to convert the chromium compound to an oxide; and,
- repeating the impregnation and heat curing steps at least once to harden and densify the structure.
- 8. The method of claim 7 wherein the refractory particles and grain are packed into a mold of predetermined shape at least during the initial impregnation and cure steps.
- 9. The method of claim 7 wherein a clay or inorganic chromium compound binder is mixed with the finely divided particles prior to forming the structure which serves to hold the particles together during the impregnation and cure cycles.
- 10. The method of claim 7 wherein the abrasive grain is selected from the group of abrasive grains consisting of chromia, tin oxide, titania, aluminum oxide, black silicon carbide, green silicon carbide, bauxite, silicic acid, iron oxide, diamonds and mixtures thereof.
- 11. The method of claim 7 wherein the particles are selected from the group of inorganic refractories consisting of oxides of aluminum, barium, beryllium, calcium, cerium, chromium, cobalt, copper, gallium, hafnium, iron, lanthanum, magnesium, manganese, molybdenum, nickel, niobium, silicon, tantalum, thorium, tin, titanium, tungsten, uranium, vanadium, yttrium, zinc, zirconium, and mixtures thereof.
- 12. The method of claim 7 wherein the solution is chromic acid.
- 13. The method of claim 7 which includes as a last step the impregnation of the hardened abrasive structure with phosphoric acid and heating and curing said structure by raising the temperature thereof to at least about 600.degree. F., but below the vitrification and sinter temperature of the refractory particles and grain in increments over a period of time sufficient to completely dry and harden the structure.
- 14. A method of producing a chemically hardened abrasive body which comprises:
- providing a non-vitrified skeletal core of relatively fine inorganic refractory material having a vitrification temperature in excess of 600.degree. F. and including a substantial amount of relatively coarse abrasive grain;
- impregnating said core with a solution of an inorganic chromium compound capable of being converted to an oxide on being heated to a temperature below the vitrification temperature of said refractory material and abrasive grain;
- drying and curing said impregnated core by heating the core to a temperature below the vitrification and sinter temperature of said refractory material and abrasive grain but sufficient to convert the chromium compound to an oxide; and
- repeating the impregnation and heat curing steps at least once to harden and densify the core.
- 15. The method of claim 14 wherein the skeletal core is of a material selected from the group of inorganic refractories consisting of oxides of aluminum, barium, beryllium, calcium, cerium, chromium, cobalt, copper, gallium, hafnium, iron, lanthanum, magnesium, manganese, molybdenum, nickel, niobium, silicon, tantalum, thorium, tin, titanium, tungsten, uranium, vanadium, yttrium, zinc, zirconium, and mixtures thereof.
- 16. The method of claim 14 wherein the abrasive grain is selected from the group of abrasive grains consisting of chromia, tin oxide, titania, aluminum oxide, black silicon carbide, green silicon carbide, bauxite, silicic acid, ferric oxide, diamonds and mixtures thereof.
- 17. The method of claim 14 wherein the solution is chromic acid.
- 18. The method of claim 14 which includes as a last step the impregnation of the hardened abrasive structure with phosphoric acid and heating and curing said structure by raising the temperature thereof to at least about 600.degree. F., but below the vitrification and sinter temperature of the refractory particles and grain in increments over a period of time sufficient to completely dry and harden the structure.
- 19. The method of claim 1 wherein the abrasive grain is silicon carbide.
- 20. The method of claim 7 wherein the abrasive grain is silicon carbide.
- 21. The method of claim 14 wherein the abrasive grain is silicon carbide.
- 22. The method of claim 1 wherein the abrasive grain is diamond.
- 23. The method of claim 7 wherein the abrasive grain is diamond.
- 24. The method of claim 14 wherein the abrasive grain is diamond.
- 25. The method of claim 1 wherein the abrasive grain is aluminum oxide.
- 26. The method of claim 7 wherein the abrasive grain is aluminum oxide.
- 27. The method of claim 14 wherein the abrasive grain is aluminum oxide.
- 28. A method of producing a grinding structure which comprises:
- wetting abrasive grains selected from the group consisting of chromia; tin oxide; titania; aluminum oxide; black silicon carbide; green silicon carbide; bauxite; silicic acid; ferric oxide; diamonds; and, mixtures thereof with a solution of a chromium compound capable of being converted to an oxide on being heated to a temperature below the vitrification temperature of said abrasive grains;
- heating said wetted grains to a temperature below the vitrification and sinter temperature of the grains but sufficient to convert the chromium compound to an oxide;
- repeating the wetting and heat curing steps at least once to increase the hardness of the oxide; and,
- bonding the abrasive grains into a grinding structure with a bonding material selected from the group of bonding materials consisting of resin, clay, alumina and soluble inorganic chromium compound binders.
- 29. The method of claim 28 wherein the bonding of the abrasive grains is with a resin bonding material.
- 30. The method of claim 28 wherein the bonding of the abrasive grains is by:
- closely packing the abrasive grains to form a porous structure;
- impregnating the porous structure with a solution of an inorganic chromium compound capable of being converted to an oxide on being heated to a temperature below the vitrification temperature of the abrasive grains;
- heat curing the impregnated structure to a temperature below the vitrification and sinter temperature of the grains but sufficient to convert the chromium compound to the oxide; and,
- repeating the impregnation and heat curing steps at least once to harden and densify the structure.
- 31. A method of producing a chemically hardened refractory abrasive body having a cutting surface which comprises:
- wetting finely divided relatively fine refractory oxide particles having a vitrification temperature in excess of 600.degree. F. selected from the group consisting of the oxides of aluminum, barium, beryllium, calcium, cerium, chromium, cobalt, copper, gallium, hafnium, iron, lanthanum, magnesium, manganese, molybdenum, nickel, niobium, silicon, tantalum, thorium, tin, titanium, tungsten, uranium, vanadium, yttrium, zinc, zirconium, and mixtures thereof with a solution of an inorganic chromium compound capable of being converted to an oxide on being heated to a temperature below the vitrification temperature of the refractory particles and relatively coarse abrasive grain;
- heating said wetted fine particles and coarse grain to a temperature sufficient to convert said chromium compound to the oxide but below the vitrification and sinter temperature of said particles and grain;
- closely packing the treated particles and grain to form a porous body;
- impregnating said porous body with a solution of an inorganic chromium compound capable of being converted to an oxide on being heated to a temperature below the vitrification temperature of the particles and grain;
- curing said impregnated body by heating same to a temperature sufficient to convert said chromium compound to the oxide, but below the vitrification and sinter temperature of the particles and grain; amd,
- repeating the impregnation and heating steps at least once to harden and densify the body.
- 32. A method of producing an abrasive structure which comprises:
- wetting abrasive grains selected from the group consisting of chromia, tin oxide, titania, aluminum oxide, black silicon carbide, green silicon carbide, bauxite, silicic acid, ferric oxide, diamonds and mixtures thereof with a wetting reagent selected from the group consisting of a solution of an inorganic chromium compound capable of being converted to an oxide on being heated; a solution of an inorganic chromium compound capable of being converted to an oxide on being heated plus kaolin; a solution of an inorganic chromium compound capable of being converted to an oxide on being heated plus aluminum oxide; a solution of an inorganic chromium compound capable of being converted to an oxide on being heated plus Kentucky ball clay; and, a solution of an inorganic chromium compound capable of being converted to an oxide on being heated plus bentonite;
- heating said wetting grains to a temperature sufficient to convert the chromium compound on the surface thereof to an oxide but below the vitrification and sinter temperature of the grains to cure said chromium compound to an oxide;
- subjecting the grains to repeated wetting and curing steps until the desired hardness of the oxide is achieved; and,
- bonding the abrasive grains into a grinding structure with a binder selected from the group of binder materials consisting of resin, clay, alumina and soluble inorganic chromium compound binders.
- 33. The method of claim 32 wherein the wetting agent is a solution of a chromium compound and the oxide is chromium oxide.
- 34. The method of claim 32 wherein the bonding of the abrasive grains is by:
- closely packing the abrasive grains to form a porous structure;
- impregnating the porous structure with a solution of an inorganic chromium compound capable of being converted to an oxide on being heated;
- curing said impregnated structure by heating same to a temperature sufficient to convert the chromium compound to the oxide but below the vitrification and sinter temperature of the grains; and,
- repeating the impregnation and curing steps at least once to harden and densify the grinding structure.
- 35. The method of claim 33 wherein the bonding of the abrasive grains is with a resin bonding material.
- 36. The method of hardening and strengthening of a fully sintered porous grinding structure which comprises:
- impregnating the structure with a solution of an inorganic chromium compound capable of being converted to an oxide on being heated;
- curing said impregnated structure by heating same to a temperature sufficient to convert the chromium compound to the oxide but below the vitrification and sinter temperature of the structure; and,
- repeating the impregnation and curing steps at least once to harden and densify the grinding structure.
- 37. A method of making crushed abrasive grain which comprises the steps of:
- closely packing finely divided relatively fine abrasive particles selected from the group consisting of chromia; tin oxide; titania; aluminum oxide; black silicon carbide; green silicon carbide; bauxite; silicic acid; ferric oxide; diamonds; and, mixtures thereof having a vitrification in excess of 600.degree. F. to form a porous structure;
- impregnating said porous structure with a solution of an impregnant selected from the group consisting of a solution of an inorganic chromium compound capable of being converted to an oxide on being heated; a solution of an inorganic chromium compound capable of being converted to an oxide on being heated plus kaolin; a solution of an inorganic chromium compound capable of being converted to an oxide on being heated plus bentonite; a solution of an inorganic chromium compound capable of being converted to an oxide on being heated plus aluminum oxide; and a solution of an inorganic chromium compound capable of being converted to an oxide on being heated plus Kentucky ball clay;
- drying and curing said impregnated structure by heating same to a temperature below the vitrification and sinter temperature thereof but sufficient to convert the chromium compound to the oxide;
- repeating the impregnation and heat curing steps at least once to harden and densify the structure; and,
- crushing the structure to form coarse abrasive grains.
- 38. The method of making a diamond grinding wheel which comprises the steps of:
- forming a slurry of diamond abrasive grains in a solution of an inorganic chromium compound capable of being converted to an oxide at a temperature of at least 600.degree. F., but below that at which the diamond grains will be oxidized;
- applying a coating of diamond and chromium compound slurry to the grinding surface of a porous abrasive grinding wheel made from an abrasive material selected from the group consisting of silicon carbide, aluminum oxide and mixtures thereof; and,
- drying and curing the grinding wheel by hearting same to a temperature of at least 600.degree. F., but below vitrification and/or sinter temperatures at which the diamond grains will be oxidized.
- 39. The method of claim 38 in which the slurry includes a substantial amount of silicon carbide grinding grains.
- 40. A chemically hardened abrasive body comprising:
- a closely packed porous mass of a substantial amount of abrasive grain and finely divided discrete particles at least the surface of which consists of a refractory oxide of at least one metallic element having a vitrification temperature in excess of 600.degree. F. essentially devoid of vitreous and/or sinter bonding between the particles with said particles being bonded together by chromic oxide at temperatures below vitrification temperature of the refractory oxide and grain and having substantial deposits of chromic oxide within the pores thereof.
- 41. A chemically hardened abrasive oxide body comprising:
- a closely packed porous mass of a substantial amount of abrasive grain and finely divided discrete particles of a refractory oxide having a vitrification temperature in excess of 600.degree. F. essentially devoid of vitreous and/or sinter bonding between the particles with said particles being bonded together by chromic oxide at temperatures below vitrification temperature of the refractory oxide and grain oxide within the pores thereof.
- 42. A body according to claim 40 wherein the abrasive grain is selected from the group consisting of chromia; tin oxide; titania; aluminum oxide; black silicon carbide; green silicon carbide; bauxite; silicic acid; ferric oxide; diamonds; and, mixtures thereof and the refractory oxide is selected from the group consisting of oxides of aluminum, barium, beryllium, calcium, cerium, chromium, cobalt, copper, gallium, hafnium, iron, lanthanum, magnesium, manganese, molybdenum, nickel, niobium, silicon, tantalum, thorium, tin, titanium, tungsten, uranium, vanadium, yttrium, zinc, zirconium, and mixtures thereof.
- 43. A body according to claim 41 wherein the abrasive grain is selected from the group consisting of chromia, tin oxide; titania; aluminum oxide; black silicon carbide; green silicon carbide; bauxite; silicic acid; ferric oxide; diamonds; and, mixture thereof and the refractory oxide is selected from the group consisting of oxides of aluminum, barium, beryllium, calcium, cerium, chromium, cobalt, copper, gallium, hafnium, iron, lanthanum, magnesium, manganese, molybdenum, nickel, niobium, silicon, tantalum, thorium, tin, titanium, tungsten, uranium, vanadium, yttrium, zinc, zirconium, and mixtures thereof.
- 44. A body according to claim 43 wherein the refractory oxide is selected from the group consisting of aluminum oxide and silicon carbide.
- 45. A body according to claim 44 where the refractory oxide is aluminum oxide.
Parent Case Info
This application is a continuation of U.S. Pat. Application Ser. No. 007,949 filed Feb. 2, 1970, now abandoned, as a division of U.S. Ser. No. 694,303, filed Dec. 28, 1967 issued as U.S. Pat. No. 3,789,096 on Jan. 29, 1974.
US Referenced Citations (9)
Divisions (1)
|
Number |
Date |
Country |
| Parent |
694303 |
Dec 1967 |
|
Continuations (1)
|
Number |
Date |
Country |
| Parent |
7949 |
Feb 1970 |
|
Patent Grant
4007020
