Diamond abrasive grain and electroplated tool having the same

Abstract

A coating method on diamond abrasive grains is used to form a conductive film on diamond abrasive grains. The conductive film has chemical composition gradient giving the diamond abrasive grain an outwardly increasing electrical conductibility as a function of film thickness. The subsequent electroplating layer can therefore more effectively embed the modified diamond abrasive grains, whilst the adhesion/bonding strength between substrate (work piece for electroplating) and the diamond abrasive grains is improved.

What is claimed is: 
     
         1 . A diamond abrasive grain, comprising: an electrical conductive layer on the surface of the diamond abrasive grain, the conductive layer having an outwardly increasing electrical conductibility along the thickness of the conductive layer, thereby providing micro-conductivity of the diamond abrasive grain. 
     
     
         2 . The diamond abrasive grain as claimed in  claim 1 , wherein the conductive layer includes a metal content, and the metal content has a chemical composition gradient along the direction of the thickness of the conductive layer. 
     
     
         3 . The diamond abrasive grain as claimed in  claim 2 , said metal content being at least one selected from the group consisting of boron, tungsten and transition metals, wherein the transition metals is selected from the group consisting of titanium, chromium, vanadium and zirconium, and the combination thereof. 
     
     
         4 . The diamond abrasive grain as claimed in  claim 1 , wherein the conductive layer includes a metal-carbide content or a metal-nitride content, and the metal-carbide content or the metal-nitride content has an outwardly increasing chemical composition gradient along the thickness of the conductive layer from the surface of the diamond abrasive grain. 
     
     
         5 . The diamond abrasive grain as claimed in  claim 1 , wherein the conductive layer has an inner portion proximate the surface of the diamond abrasive grain, the inner portion has an electric resistance ranged from 70 to 100 mΩ-cm, the conductive layer has an outer portion away from the surface of the diamond abrasive grain, the outer portion has an electric resistance ranged from 5 to 20 mΩ-cm. 
     
     
         6 . The diamond abrasive grain as claimed in  claim 1 , wherein the diamond particle sized from 1 um to 600 um. 
     
     
         7 . An electroplated abrasive tool, comprising:
 an abrasive surface; and   a plurality of diamond abrasive grains firmly retained on the abrasive surface of the abrasive tool by an electroplated metal matrix, wherein each of the diamond abrasive grains includes a conductive layer with electrical micro-conductibility on the surface of abrasive grains.   
     
     
         8 . The electroplated tool as claimed in  claim 6 , wherein the conductive layer has a metal content therein and the metal content is a gradient of chemical composition, said metal content comprises boron, tungsten or transition metals, the transition metals comprises titanium, chromium, vanadium and zirconium. 
     
     
         9 . The electroplated tool as claimed in  claim 6 , wherein the conductive layer includes a metal-carbide content or a metal-nitride content therein, and the metal-carbide content or the metal-nitride content has an outwardly increasing chemical composition gradient along the thickness of the conductive layer from the surface of the diamond abrasive grain. 
     
     
         10 . The electroplated tool as claimed in  claim 6 , wherein the conductive layer has an inner portion proximate the surface of the diamond abrasive grain, the inner portion has an electric resistance ranged from 70 to 100 mΩ-cm, the conductive layer has an outer portion away from the surface of the diamond abrasive grain, the outer portion has an electric resistance ranged from 5 to 20 mΩ-cm. 
     
     
         11 . The electroplated tool as claimed in  claim 6 , wherein the electroplated metal matrix is partially or entirely plated on each of the diamond abrasive grains with particle size from 1 um to 600 um.