Cemented carbide insert

Abstract

Methods of making a coated cemented carbide body include: forming a powder mixture having WC, 5-12 wt % Co, 3-11% cubic carbides of Ta and Ti with a ratio of Ta/Ti is 1.0-4.0; adding N in an amount of 0.6-2.0% of the weight of Ta and Ti; milling and spray-drying the mixture to form a powder; compacting and sintering the powder at a temperature of 1300-1500° C., in a controlled atmosphere of about 50 mbar followed by cooling, whereby a body having a binder phase enriched and essentially gamma-phase free surface zone of 5-50 μm in thickness is obtained; applying a pre-coating treatment to the body; and appling a hard, wear-resistant coating to the body.

1. A method of making a coated cemented carbide body having a gamma phase-free and binder rich surface zone comprising the steps of:
 (i) forming a powder mixture comprising WC, 5-12 wt. % Co, 3-11 wt. % cubic carbides of Ta and Ti, where the ratio of Ta/Ti is 1.0-4.0;  
 (ii) adding N in an amount of 0.6-2.0% of the weight of Ta and Ti;  
 (iii) milling and spray drying the mixture to form a powder material with the desired properties;  
 (iv) compacting and sintering the powder material at a temperature of 1300-1500° C., in a controlled atmosphere of about 50 mbar followed by cooling, whereby a body having a binder phase enriched and essentially gamma phase free surface zone of 5-50 μm in thickness is obtained;  
 (v) applying a pre-coating treatment to the body; and  
 (vi) applying a hard, wear resistant coating.  
 
     
     
       2. The method of  claim 1 , further comprising adding a pressing agent and W to the powder mixture in an amount to give the body a CW ratio of 0.75-0.95, the CW ratio is expressed as CW ratio=M s /(wt. % Co*0.0161), where M s  is the measured saturization magnetization of the body and wt. % Co is the weight percentage of Co in the cemented carbide. 
     
     
       3. The method according to  claim 1 , wherein the powder mixture comprises 7-10 wt. % of cubic carbides of the metals Ta and Ti. 
     
     
       4. The method according to  claim 1 , wherein the coating is applied using a CVD-technique. 
     
     
       5. The method according to  claim 1 , wherein the coating is applied using a MT-CVD-technique. 
     
     
       6. The method of  claim 1 , wherein the surface zone is approximately  10 -   30  μm thick.   
     
     
       7. The method of  claim 1 , wherein the surface zone has a binder phase content  1 . 2 -   2 . 0  times the binder phase content in the rest of the body.   
     
     
       8. The method of  claim 1 , wherein the Ta/Ti- ratio is  2 . 0   -   3 . 0 .   
     
     
       9. The method of  claim 2 , wherein the CW ratio is  0 . 8 -   0 . 85 .   
     
     
       10. The method of  claim 1 , wherein the Co content is  9 -   11  wt.  %. 
     
     
       11. The method of  claim 1 , wherein the combined content of TaC and TiC is  3 -   11  wt.  %. 
     
     
       12. The method of  claim 1 , wherein the body comprises WC having a grain size of  1 . 0 -   4 . 0  μm.   
     
     
       13. The method of  claim 12 , wherein the grain size is  1 . 5 -   3 . 0  μm.   
     
     
       14. The method of  claim 1 , wherein the coating comprises a  3 -   12  μm columnar TiCN - layer, followed by a  1   -   8  μm thick Al   2   O   3 - layer.   
     
     
       15. The method of  claim 14 , wherein the coating comprises an outermost layer of TiN. 
     
     
       16. The method of  claim 15 , comprising removing the TiN layer at an edge line of the body. 
     
     
       17. The method of  claim 14 , wherein the Al 2   O   3 - layer is κ - Al   2   O   3 . 
     
     
       18. The method of  claim 17 , wherein the coating comprises an outermost layer of TiN. 
     
     
       19. The method of  claim 18 , comprising removing the TiN layer at an edge line of the body.