Coated Abrasives

Abstract

A coated super-hard abrasive comprises a core of super-hard abrasive material, which is typically diamond or cBN based, an inner layer of a metal carbide, nitride, boride, boronitride or carbonitride chemically bonded to an outer surface of the super-hard abrasive material and one or more outer layers of a metal carbide, nitride, boride or carbonitride physically deposited on the inner layer. In the case of a single outer layer, the single outer layer has a composition gradient extending through its thickness, and in the case of more than one outer layer, the composition of each layer is different to provide a gradient of material through the various layers. In the case of several outer layers, each layer may also include a composition gradient.

1 . A coated super-hard abrasive comprising a core of super-hard abrasive material, an inner layer of a metal carbide, nitride, boride, boronitride or carbonitride chemically bonded to an outer surface of the super-hard abrasive material and one or more outer layers of a metal carbide, nitride, boride or carbonitride physically deposited on the inner layer, wherein in the case of a single outer layer, the single outer layer has a composition gradient extending through its thickness, and in the case of more than one outer layer, the composition of each layer is different to provide a gradient of material through the various layers. 
   
   
       2 . A coated super-hard abrasive according to  claim 1 , wherein in the case of several outer layers, each layer includes a composition gradient. 
   
   
       3 . A coated super-hard abrasive according to  claim 1  or  claim 2 , wherein the outer layer(s) is/are deposited by physical vapour deposition. 
   
   
       4 . A coated super-hard abrasive according to any one of the preceding claims, wherein the ultra-hard abrasive material is diamond or cBN based. 
   
   
       5 . A coated super-hard abrasive according to  claim 4 , wherein the ultra-hard material is selected from the group comprising diamond or cBN grit, a PCD substrate, a thermally stable PCD (TSPCD) substrate, a PcBN substrate, a CVD diamond film, and a single crystal diamond substrate. 
   
   
       6 . A coated super-hard abrasive according to any one of the preceding claims, wherein the inner layer is formed from an element capable of forming (singly or in combination) carbides, nitrides or borides to the surface(s) of the abrasive material when applied using a hot coating process. 
   
   
       7 . A coated super-hard abrasive according to  claim 6 , wherein the element is selected from the group comprising groups IVa, Va, VIa, IIIb and IVb of the periodic table. 
   
   
       8 . A coated super-hard abrasive according to any one of the preceding claims, wherein the inner layer is a titanium or chromium carbide coating in the case of a diamond based core, or a titanium or chromium nitride or boride coating in the case of a cBN based core. 
   
   
       9 . A coated super-hard abrasive according to any one of the preceding claims, wherein the outer layer(s) is/are comprised (whether singly or in combination) of carbides, nitrides, borides, oxides or silicides of metals from groups IVa, Va, VIa, IIIb or IVb of the periodic table. 
   
   
       10 . A coated super-hard abrasive according to  claim 9 , wherein the outer layer(s) is/are preferably comprised of titanium carbide, titanium carbonitride, titanium nitride, titanium boride, or titanium boronitride.