Polycrystalline superhard material

Abstract

A method for making polycrystalline superhard material comprises providing an electrically conductive substrate defining at least one deposition surface, electrophoretically depositing charged superhard particles or grains on to the deposition surface(s) of the substrate to form a pre-sinter body, and subjecting the pre-sinter body to a temperature and pressure at which the superhard material is thermodynamically stable, sintering and forming polycrystalline superhard material. There is also disclosed a superhard wear element comprising a polycrystalline superhard material produced by such a method.

1 . A method for making polycrystalline superhard material, the method comprising providing an electrically conductive substrate defining at least one deposition surface, electrophoretically depositing charged superhard particles or grains on to the deposition surface(s) of the substrate to form a pre-sinter body, and subjecting the pre-sinter body to a temperature and pressure at which the superhard material is thermodynamically stable, sintering and forming polycrystalline superhard material. 
     
     
         2 . A method according to  claim 1 , wherein the substrate forms the cathode of an electrophoretic cell apparatus, the superhard particles or grains being suspended in a liquid in contact with the deposition surface(s) and an anode, method further comprising depositing the superhard particles or grains on the deposition surface(s) upon application of an electric potential between the substrate and the anode, the superhard particles or grains being positively charged so as to be so deposited. 
     
     
         3 . A method according to  claim 2 , further comprising positioning the anode to define a complementary surface or surfaces opposing the deposition surface(s) of the substrate. 
     
     
         4 . A method according to any one of the preceding claims  claim 1 , wherein the step of electrophoretically depositing charged superhard particles or grains comprises depositing the superhard particles or grains on the substrate in a series of layers or strata. 
     
     
         5 . A method according to  claim 1 , wherein the deposition surface(s) of the substrate is/are masked in certain areas or regions, the step of depositing the superhard particles or grains comprising depositing the superhard particles or grains on exposed portions of the deposition surface(s) so as to form discrete three dimensional polycrystalline superhard structures. 
     
     
         6 . A method according to  claim 4 , wherein the step of electrophoretically depositing charged superhard particles or grains comprises to form various layers or three dimensional structures of polycrystalline superhard material, comprises forming the layers or three dimensional structures to have differing structural characteristics from one another. 
     
     
         7 . A method according to  claim 1 , comprising forming a polycrystalline superhard material having a superhard grain content of at least 80 percent and at most 98 percent of the volume of the polycrystalline superhard material. 
     
     
         8 . A method according to  claim 1 , comprising forming polycrystalline diamond material, the superhard particles or grains comprising diamond. 
     
     
         9 . A method according to  claim 8 , wherein the method comprises forming polycrystalline diamond material comprising at most 10 volume percent of a catalyst material for diamond. 
     
     
         10 . A method according to  claim 1 , wherein comprising forming a PCBN material, the superhard particles or grains comprising cBN. 
     
     
         11 . A superhard wear element comprising a polycrystalline superhard material produced by a method as claimed in  claim 1 . 
     
     
         12 . A superhard wear element as claimed in  claim 11 , comprising a plurality of regions, each region comprising polycrystalline superhard material having at least one different structural characteristic. 
     
     
         13 . A superhard wear element as claimed in  claim 11 , in which the superhard wear element is for use in machining, drilling or cutting a workpiece comprising metal.