Sintered part and the method for production thereof

Abstract

The invention relates to a sintered part consisting of a hard metal, in particular WC with Co, Ni and/or Fe binders-based hard metal, or cermet, in particular on the base of composition consisting of (Ti, W) (C, N) or (Ti, Mo) (C, N) with Co, Ni and/or Fe binders and to a method for producing such a sintered part. The inventive method consists in exposing a sintered part totally or partially to an active plasma gaseous phase at a maximum pressure of 3×10 4 Pa during heating, sintering or after sintering, at least during a certain time preferably during a time period ranging from 10 to 100 min.

1 . A sintered body comprised of a hard metal, especially a hard metal based on WC with a Co, Ni and/or Fe binder proportions based on hard metal, or a cermet, especially based on a (Ti,W)(C,N) or (Ti,Mo)(C,N) with binder components of Co, Ni and/or Fe, characterized in that the sintered body during a heating up, during the sintering or after completion of finish sintering is treated at least timewise, preferably over a time span of at least 10 min to 100 min completely or only partially with a plasma-activated gas phase at a pressure of a maximum of 3×10 −4  Pa.  
   
   
       2 . The sintered body according to  claim 1 , characterized in a surface proximal boundary zone which contains by migration and/or diffusion material from the plasma-activated gas phase or compounds produced therefrom.  
   
   
       3 . The sintered body according to  claim 1 , characterized in that the sintered body is treated in a plasma-activated gas phase which contains nitrogen, carbon, boron, metals, compounds or mixtures thereof or corresponding precursors.  
   
   
       4 . The sintered body according to  claim 1  characterized in that the surface-proximal zone of the sintered body, contains nitride particles of a particle size ≧0.2 μm.  
   
   
       5 . The sintered body according to  claim 1  characterized by a lattice gradient of the sintered body from the surface toward the interior of the body.  
   
   
       6 . A method for producing a sintered body from a hard metal or a cermet according to  claim 1  characterized in that the body pressed to a green body and subjected to treatment in a powder metallurgical manner during the heating up to the sintering temperature, during the sintering or after subsequent finish sintering is at least timewise, preferably over a time span of at least 10 min to 100 min, completely or only partially treated with a plasma-activated gas phase at a pressure of a maximum of 3×10 −4  Pa preferably at a temperature between 900° C. to 1350° C.  
   
   
       7 . The method according to  claim 6 , characterized in that the plasma activation is carried out by microwaves and/or by a glow discharge, preferably by means of a pulsed process in which the sintered body is connected as a cathode and to which a pulsed direct current voltage is applied.  
   
   
       8 . The method according to claims  6 , characterized in that the plasma-activated gas phase contains nitrogen, carbon, boron, metals, compounds or mixtures thereof.  
   
   
       9 . The method according to  claim 6 , characterized in that prior to admission of a reactive gas or a reactive gas mixture, the gas phase contains an inert gas, especially a noble gas and/or a chemical reducing agent, especially hydrogen.  
   
   
       10 . The method according to  claim 6 , characterized in that during the treatment in the plasma-activated gas phase, parts of the surface of the substrate body are masked.