Binder redistribution within a cemented carbide mining insert

Abstract

A method of redistributing the binder phase of a cemented carbide mining insert having one or more hard-phase components and a binder includes the steps of: a) providing a green cemented carbide mining insert; b) applying at least one binder puller selected from a metal oxide or a metal carbonate to the surface of the green cemented carbide mining insert; and c) sintering the green cemented carbide mining insert, the metal oxide or metal carbonate being only applied to at least one local area on the surface of the green cemented carbide mining insert. Moreover, a cemented carbide having a hardness gradient and the use thereof is also provided.

1 . A method of redistributing a binder phase of a cemented carbide mining insert comprising a WC hard-phase component, optionally one or more further hard-phase components and a binder, the method comprising the steps of:
 a) providing a green cemented carbide mining insert;   b) applying at least one binder puller selected from a metal oxide or a metal carbonate to a surface of the green cemented carbide mining insert; and   c) sintering the green carbide mining insert, wherein the metal oxide or metal carbonate is only applied to at least one local area on the surface of the green cemented carbide mining insert.   
     
     
         2 . The method according to  claim 1 , wherein the at least one binder puller is Cr 2 O 3 . 
     
     
         3 . The method according to  claim 1 , further comprising the step between steps b) and c) of:
 applying at least one binder pusher, selected from a metal carbide, a carbon powder or a mixture thereof, to at least one different local area on the surface of the green cemented carbide mining insert.   
     
     
         4 . The method according to  claim 1 , wherein the at least one binder puller and the at least one binder pusher are applied to substantially opposing local areas of the surface of the green cemented carbide mining insert. 
     
     
         5 . The method according to  claim 1 , wherein the at least one binder puller and the at least one binder pusher are applied symmetrically. 
     
     
         6 . The method according to  claim 1 , wherein the at least one binder puller and at least one binder pusher are applied asymmetrically. 
     
     
         7 . The method according to  claim 1 , wherein post sintering the cemented carbide mining insert is treated with a tumbling process. 
     
     
         8 . The method according to  claim 7 , wherein the tumbling process is a “High Energy Tumbling” process, wherein post tumbling a homogenous cemented carbide mining insert has been deformation hardened such that ΔHV3%≥9.72−0.00543*HV3 bulk . 
     
     
         9 . A cemented carbide mining insert comprising:
 one or more hard-phase components and   a binder, wherein there is a hardness gradient from a first part of the surface of the cemented carbide mining insert to a second part of the surface of the cemented carbide mining insert, wherein the first part of the surface is substantially opposing the second part of the surface, such that post sintering the first part of the surface of the sintered cemented carbide mining insert is between 30HV3 softer and 80HV3 harder than the second part of the surface, and wherein the first part of the surface is between 5 and 120 HV3 harder than a bulk of the insert and the second part of the surface is between 20HV3 and 70HV3 harder than the bulk.   
     
     
         10 . The cemented carbide mining insert according to  claim 9 , wherein a maximum binder concentration (% binder-max) is less than 20% higher than a minimum binder concentration (% binder-min) within the cemented carbide mining insert. 
     
     
         11 . The cemented carbide mining insert according to  claim 10 , wherein the % binder-min is at a depth, in percentage of a total height of the sintered cemented carbide mining insert, of between 1-50% from the first part of the surface. 
     
     
         12 . The cemented carbide mining insert according to  claim 9 , wherein there is a first binder concentration maximum (% binder-max1) at the first part of the surface and there is a second binder concentration maximum (% binder-max2) at a depth, in percentage of a total height of the sintered cemented carbide mining insert, of between 15-75% from the first part of the surface. 
     
     
         13 . The cemented carbide mining insert according to  claim 9 , wherein there is a first chromium concentration maximum (% Cr-max1) at the first part of the surface. 
     
     
         14 . The cemented carbide mining insert according to  claim 13 , wherein there is additionally a second chromium concentration maximum (% Cr-max2) at the second part of the surface, such that % Cr-max1>% Cr-max2, and wherein there is a chromium concentration minimum (% Cr-min) located between % Cr-max1 and % Cr-max2. 
     
     
         15 . The cemented carbide mining insert according to  claim 14 , wherein the % Cr-min is at a depth, in percentage of a total height of the sintered cemented carbide mining insert, of between 40-99%, from first part of the surface.