Superabrasive composition and superabrasive article comprising same for grinding CRT front panel

Abstract

A grinding article, which has a grinding layer derived from a superabrasive composition comprising a mixture of diamond and cubic boron nitride (CBN) particles in a volume ratio of 8.5:1.5 to 9.5:0.5 and a substrate element assembled for securing the grinding layer by way of forming a three-dimensional bonding interface therewith provides excellent grinding efficiency when used in grinding a CRT front glass panel.

What is claimed is:  
     
         1 . A superabrasive composition for grinding the front glass panel of a cathode ray tube, which comprises superabrasive particles and a bonding material, the superabrasive particles being a mixture of diamond particles and cubic boron nitride (CBN) particles having a mix ratio of 8.5:1.5 to 9.5:0.5 in volume.  
     
     
         2 . The composition of  claim 1 , wherein the superabrasive particles have an average particle size of 75 to 90 μm and a toughness index of 50 to 60.  
     
     
         3 . The composition of  claim 1 , wherein the superabrasive particles have an average particle size of 30 to 38 μm and a toughness index of 50 to 60.  
     
     
         4 . The composition of  claim 1 , wherein the diamond particles have an average particle size of 30 to 38 μm and a toughness index of 50 to 60, and the CBN particles, an average particle size of 30 to 38 μm and a toughness index of 40 to 50.  
     
     
         5 . The composition of  claim 1 , wherein the superabrasive particles are combined with a bonding material in a mix ratio of 1.5:8.5 to 2.5:7.5 by volume.  
     
     
         6 . The composition of  claim 1 , therein the bonding material is metallic or a mixture of a metal oxide and a resin.  
     
     
         7 . The composition of  claim 6 , wherein the resin content of the metal oxide-resin mixture ranges from 70 to 90% by volume.  
     
     
         8 . A grinding article for grinding the front glass panel of a cathode ray tube, which comprises a superabrasive grinding layer formed by sintering the superabrasive composition of any one of  claims 1  to  7  and a substrate element for securing the superabrasive grinding layer, said grinding layer having a cylindrical protrusion extending outward from a portion of the bottom surface thereof, and the substrate element, which has on a portion of the top surface thereof a dimple which is shaped to closely receive said cylindrical protrusion, being tightly bonded to the grinding layer forming an interface which extends from the remaining portion of the bottom surface of the grinding layer to the surface of said protrusion.  
     
     
         9 . The article of  claim 8 , wherein an additional structural feature for securing the grinding layer to the substrate element is provided at said interface.  
     
     
         10 . The article of  claim 9 , wherein the additional structural feature is selected from a flange formed at a lower portion of the cylindrical protrusion, a circumferential groove positioned at the portion of the interface where the bottom surface of the grinding layer meets the top surface of the substrate element, a screw-groove provided on the outer periphery of the cylindrical protrusion, and a combination thereof.  
     
     
         11 . A process for the preparation of a grinding article for grinding the front glass panel of a cathode ray tube, which comprises the steps of loading a pre-fabricated substrate element into a mold, introducing the superabrasive composition of any one of  claims 1  to  8  over the substrate element, sealing the mold and hot-pressing at a temperature ranging from 150 to 800° C. under a pressure ranging from 0.1 to 0.5 ton/cm 2 .  
     
     
         12 . The process of  claim 11 , wherein the grinding article comprises a superabrasive grinding layer formed by sintering said superabrasive composition and a substrate element for securing the superabrasive grinding layer, said grinding layer having a cylindrical protrusion extending outward from a portion of the bottom surface thereof, and the substrate element, which has on a portion of the top surface thereof a dimple which is shaped to closely receive said cylindrical protrusion, being tightly bonded to the grinding layer forming an interface which extends from the remaining portion of the bottom surface of the grinding layer to the surface of said. protrusion.