Super-hard structure, tool element and method of making same

Abstract

A method for making a treated super-hard structure, the method including providing a super-hard structure comprising super-hard material selected from polycrystalline cubic boron nitride (PCBN) material or thermally stable polycrystalline diamond (PCD) material; subjecting the super-hard structure to heat treatment at a treatment temperature of greater than 700 degrees centigrade at a treatment pressure at which the super-hard material is not thermodynamically stable, for a treatment period of at least about 5 minutes to produce the treated super-hard structure.

1 - 31 . (canceled) 
     
     
         32 . A method for making a heat treated polycrystalline cubic boron nitride (PCBN) structure, the method including
 providing a substrate comprising cemented carbide material,   providing a PCBN structure joined to the substrate, the PCBN structure comprising PCBN material;   heat treating the PCBN structure by increasing the temperature to a temperature of greater than 700 degrees centigrade for a treatment period of at least 5 minutes to produce the heat treated PCBN structure.   
     
     
         33 . A method as claimed in  claim 32 , in which the treatment pressure is at most ambient pressure. 
     
     
         34 . A method as claimed in  claim 32 , in which the treatment pressure is at most 2 GPa. 
     
     
         35 . A method as claimed  claim 32 , including providing the PCBN structure comprised in a construction, in which the PCBN structure is formed joined to a substrate comprising cemented carbide material, and treating the construction to provide a treated construction. 
     
     
         36 . A method as claimed in  claim 32 , including cooling the PCBN structure from the treatment temperature at a mean quench rate of at most 100 degrees centigrade per minute. 
     
     
         37 . A method as claimed in  claim 32 , including subjecting the treated PCBN structure to a further heat treatment, including heating the PCBN structure to a temperature of at least 700 degrees centigrade for a period of at least 1 minute. 
     
     
         38 . A method as claimed in  claim 32 , including processing the treated PCBN structure to form an element for a tool. 
     
     
         39 . A method as claimed in  claim 38 , including heating the element at a treatment temperature of greater than 700 degrees centigrade for a treatment period of at least 1 minute to produce a treated element. 
     
     
         40 . A method as claimed  claim 32 , in which the PCBN structure comprises cBN grains dispersed in a matrix comprising material including Ti and material including Al, the content of the cBN grains being at least 40 volume percent of the PCBN structure. 
     
     
         41 . A method as claimed in  claim 40 , in which the matrix comprises material selected from titanium carbide, titanium nitride, titanium carbonitride, boride of aluminium, nitride of aluminium or any combination of two or more of these materials. 
     
     
         42 . A method as claimed in  claim 32 , including providing the PCBN structure as an integral part of a construction comprising the PCBN structure sintered onto a cemented carbide substrate, and heating the construction in a substantially non-oxidising atmosphere a temperature in the range from greater than 700 degrees centigrade to 1,100 degrees centigrade for at least 30 minutes. 
     
     
         43 . A method as claimed in  claim 32 , in which the PCBN structure is joined to a cemented carbide substrate; the cemented carbide substrate comprising tungsten carbide (WC) particles and a binder material comprising cobalt (Co), the WC particles having mean size D of at least 0.5 microns, the content of the WC particles in the substrate being at least 75 weight percent and at most 95 weight percent, and the content of the binder material in the substrate being at least 5 weight percent and at most about 25. 
     
     
         44 . The method as claimed in  claim 43 , wherein the treatment period in hours is at least (0.8×D)−0.15 and at most about (4.3×D)−1.7. 
     
     
         45 . A method as claimed in  claim 32 , in which the PCBN structure has a diameter or edge length of at least 20 mm. 
     
     
         46 . A method as claimed  claim 32 , in which the treatment period is split up into sub-periods separated from each other by cooling of the PCBN structure, the cumulative treatment time being at least 5 minutes. 
     
     
         47 . A method as claimed in  claim 32 , including cooling the PCBN structure from the treatment temperature to a temperature of at most 200 degrees centigrade at a mean quench rate of at most 100 degrees centigrade per second. 
     
     
         48 . A method as claimed in  claim 32 , in which the PCBN structure is disc-shaped and as a diameter of at least 20 mm. 
     
     
         49 . A method as claimed in  claim 32 , in which a combined thickness of the PCBN structure and the substrate is at least 1.5 mm. 
     
     
         50 . A method as claimed in  claim 32 , in which a thickness of the PCBN structure is at least 0.5 mm and a thickness of the substrate is at least 2 mm.