Method for preparing of ceramic shaped part, apparatus and use thereof

Abstract

Method and apparatus for preparing of at least one ceramic shaped part. A cavity is provided between at least one external shape and at least one internal shape. A Si-containing powder composition is then provided in the cavity. The composition is then heated in a reactive gas atmosphere to obtain a reaction bounded ceramic shaped part. Use of the apparatus is also described.

1 - 26 . (canceled) 
     
     
         27 . A method for preparing at least one ceramic mould part of reaction bonded silicon nitride, comprising:
 providing a cavity between at least one external mould and at least one internal mould;   perforating at least one of the external and/or internal mould;   placing a Si-containing powder composition in the cavity; and   heating the Si-containing powder composition in a reactive gas atmosphere to a temperature at which a reaction bonded silicon nitride mould part is obtained.   
     
     
         28 . The method according to  claim 27 , wherein the at least one internal mould are at least two internal moulds, the method comprising:
 separating the at least two internal moulds from each other by inserting a thermal resistant deformable material.   
     
     
         29 . The method according to  claim 28 , wherein the thermal resistant deformable material is chosen from at least one of: graphite felt, graphite wool, and graphite bar. 
     
     
         30 . The method according to  claim 27 , further comprising:
 applying a temperature resistant perforated foil to at least one external mould; and   coating the temperature resistant perforated foil with a silicon nitride slurry.   
     
     
         31 . The method according to  claim 27 , further comprising:
 applying a temperature resistant perforated foil to at least one internal mould; and   coating the temperature resistant perforated foil with a silicon nitride slurry.   
     
     
         32 . The method according to  claim 30 , wherein the slurry comprises a powder containing silicon nitride having particle size ≦100 μm. 
     
     
         33 . The method according to  claim 31 , wherein the slurry comprises a powder containing silicon nitride having particle size ≦100 μm. 
     
     
         34 . The method according to  claim 27 , wherein the Si-containing powder composition is chosen from at least one of: silicon, silicon carbide, and silicon nitride. 
     
     
         35 . The method according to  claim 27 , wherein the reactive gas atmosphere contains at least nitrogen. 
     
     
         36 . The method according to  claim 27 , wherein at least one external mould and at least one internal mould comprise a graphite-containing material. 
     
     
         37 . The method according to  claim 30 , wherein at least one external mould and at least one internal mould comprise a graphite-containing material. 
     
     
         38 . The method according to  claim 31 , wherein at least one external mould and at least one internal mould comprise a graphite-containing material. 
     
     
         39 . Apparatus for preparing at least one ceramic mould part made of reaction bonded silicon nitride, the apparatus comprising:
 at least one cavity between at least one external mould and at least one internal mould, wherein at least one of the external or internal moulds are perforated;   means for inserting a Si-containing powder composition; and   means for heating in a reactive gas atmosphere.   
     
     
         40 . The apparatus according to  claim 39 , wherein:
 the at least one internal mould has a thermal expansion coefficient higher than the thermal expansion coefficient of a reaction bonded silicon nitride ceramic mould part; and   the at least one external mould has a thermal expansion coefficient lower than of the reaction bonded silicon nitride ceramic mould part.   
     
     
         41 . The apparatus according to  claim 39 , wherein the at least one internal mould are at least two internal moulds, the apparatus further comprising at least one thermal resistant deformable material separating the at least two internal moulds. 
     
     
         42 . The apparatus according to  claim 40 , wherein the at least one internal mould are at least two internal moulds, the apparatus further comprising at least one thermal resistant deformable material separating the at least two internal moulds. 
     
     
         43 . The apparatus according to  claim 41 , wherein the thermal resistant deformable material is chosen from graphite felt, graphite wool or graphite bar. 
     
     
         44 . The apparatus according to  claim 42 , wherein the thermal resistant deformable material is chosen from graphite felt, graphite wool or graphite bar. 
     
     
         45 . A method of using of a cavity provided between at least one external mould and at least one internal mould, the method comprising:
 perforating at least one of the external or internal mould;   providing a Si-containing powder composition in the cavity; and   heating the powder composition in a reactive gas atmosphere to a temperature in which a ceramic mould part of reaction bonded silicon nitride is prepared.   
     
     
         45 . The method of  claim 44 , further comprising:
 providing a slurry comprising a powder containing silicon nitride.   
     
     
         46 . The method of  claim 44 , wherein the gas atmosphere comprises nitrogen.