Process for producing a turbine wheel for an exhaust gas turbocharger

Abstract

The invention relates to a process for producing a turbine wheel for an exhaust gas turbocharger by metal powder injection molding, which comprises the following steps: (a) provision of a feedstock comprising a metal powder and a binder, (b) provision of a tool which comprises a negative mold of the turbine wheel to be produced for metal powder injection molding of the turbine wheel, (c) introduction of a rotationally symmetrical core comprising a binder into the negative mold of the tool provided in process step (b) and alignment of the core so that it is aligned symmetrically about the axis of rotation of the turbine wheel to be produced, (d) production of a green body by metal powder injection molding of the feedstock provided in process step (a) around the core, (e) carrying out of a binder removal step to remove the binder from the green body in order to obtain a molding in the shape of the turbine wheel, and (f) sintering of the molding.

1 - 9 . (canceled) 
     
     
         10 . A process for producing a turbine wheel for an exhaust gas turbocharger by metal powder injection molding, the process comprising:
 a) providing a feedstock comprising
 (A) from 40 to 90% by volume of a sinterable pulverent nickel-based alloy or of a titanium-based alloy, 
 (B) from 10 to 60% by volume of a mixture of
 (B1) from 80 to 98% by weight of a polyethylene homopolymer or copolymer, and 
 (B2) from 2 to 20% by weight of a polyolefin or a mixture of polyolefins as binder, and 
 
 (C) from 0 to 5% by volume of a dispersant; 
   b) providing a tool which comprises negative mold of the turbine wheel to be produced for metal powder injection molding of the turbine wheel;   c) introducing a rotationally symmetrical core comprising a binder into the negative mold of the tool provided in process step (b) and alignment of the core so that it is aligned symmetrically about the axis of rotation of the turbine wheel to be produced;   d) producing a green body by metal powder injection molding of the feedstock provided in process step (a) around the core;   e) removing the binder and at the same time removing the core in order to obtain a molding in the shape of the turbine wheel; and   f) sintering the molding.   
     
     
         11 . The process according to  claim 10 , wherein a core comprising the binder which is comprised in the feedstock provided in process step (a) is introduced in process step (c). 
     
     
         12 . The process according to  claim 10 , wherein the molding is mounted in at least one holding device in process step (f). 
     
     
         13 . The process according to  claim 10 , wherein the core introduced in process step (c) has a volume from 5 to 60% of the volume of the turbine wheel. 
     
     
         14 . The process according to  claim 10 , wherein process step (e) is carried out at a temperature in the range from 10 to 180° C. 
     
     
         15 . The process according to  claim 10 , wherein process step (f) is carried out at a temperature in the range from 250 to 1500° C. 
     
     
         16 . A turbine wheel for an exhaust gas turbocharger having a hollow space structure which is symmetrical about the rotational axis of the turbine wheel and has a volume of from 5 to 60% of the volume of the turbine wheel, produced by a process according to  claim 10 .