Method for the production of a sealing segment, and sealing segment to be use in compressor and turbine components

Abstract

A method is provided for producing a sealing segment for use in compressor and turbine components, by powder injection molding, the method comprising the following steps: a) preparing a first homogeneous mixture of a metal powder or a mixture of metal powders or a ceramic powder or a mixture of ceramic powders and at least one binding agent; b) producing a first molded article by injection molding the first mixture; c) preparing a second homogeneous mixture of a metal powder or a mixture of metal powders or a ceramic powder or a mixture of ceramic powders and at least one binding agent, the second mixture being selected to exhibit a lower abrasion resistance than the first mixture following a subsequent joint sintering process; d) producing a second molded article as a rub strip by injection molding the second mixture; and e) joining the first and second molded articles to produce the sealing segment. A sealing segment is also provided for use in compressor and turbine components, composed of at least one first molded article as a base element and at least one second molded article having lower abrasion resistance than the first molded article, as a rub strip, the first and the second molded articles each being produced by powder injection molding.

1 - 20 . (canceled) 
   
   
       21 . A method for producing a sealing segment for use in compressor and turbine components, by powder injection molding, the method comprising the following steps:
 a) preparing a first homogeneous mixture of a metal powder or a mixture of metal powders or a ceramic powder or a mixture of ceramic powders and at least one binding agent;   b) producing a first molded article by injection molding the first mixture;   c) preparing a second homogeneous mixture of a metal powder or a mixture of metal powders or a ceramic powder or a mixture of ceramic powders and at least one binding agent, the second mixture being selected to exhibit a lower abrasion resistance than the first mixture following a subsequent joint sintering process;   d) producing a second molded article as a rub strip by injection molding the second mixture; and   e) joining the first and second molded articles to produce the sealing segment, the lower abrasion resistance of the second molded article being achieved by reducing the metal powder or ceramic powder content in the second mixture.   
   
   
       22 . The method as recited in  claim 21 , wherein the first and second molded articles are joined immediately following the production thereof and prior to releasing of the first and second molded articles in a joint process. 
   
   
       23 . The method as recited in  claim 21 , wherein the first and second molded articles are joined following a separate release process and prior to a subsequent joint sintering process that the first and second molded articles undergo. 
   
   
       24 . The method as recited in  claim 21 , wherein the first and second molded articles are joined following a separate release and sintering process that the first and second molded articles undergo. 
   
   
       25 . The method as recited in  claim 21 , wherein the sealing segment is an abradable coating for sealing a radial gap between a rotating rotor blade and a housing of a gas turbine. 
   
   
       26 . The method as recited in  claim 21 , wherein the sealing segment has a honeycomb design. 
   
   
       27 . The method as recited in  claim 21 , wherein the metal powder or mixtures of metal powders or ceramic powder or mixtures of ceramic powders include all sinterable metals and metal alloys, all sinterable ceramics, and carbides. 
   
   
       28 . The method as recited in  claim 27 , wherein the sinterable ceramics are nitride ceramics, oxide ceramics or silicate ceramics. 
   
   
       29 . The method as recited in  claim 21 , wherein the metal powder or ceramic powder content is 15-30% by volume in the second homogenous mixture. 
   
   
       30 . The method as recited in  claim 21 , wherein the lower abrasion resistance of the second molded article is achieved by using metal or ceramic powders having reduced sintering activity. 
   
   
       31 . The method as recited in  claim 21 , wherein the lower abrasion resistance of the second molded article is achieved by admixing binder polymers, which do not entirely decompose during release and/or sintering processes, into the second mixture. 
   
   
       32 . The method as recited in  claim 31 , wherein the binder polymers are selected from the group including the phenolic resins or novolak. 
   
   
       33 . The method as recited in  claim 21 , wherein a higher abrasive wear rate of the second molded article is achieved by admixing fillers into the second mixture. 
   
   
       34 . The method as recited in  claim 33 , wherein the fillers are formed from easily cleavable inert materials, such as graphite, bentonite or hexagonal boron nitride and/or from materials which at least partially decompose during the release and/or sintering process and contribute to the pore formation in the second molded article. 
   
   
       35 . The method as recited in  claim 21 , wherein a multiplicity of homogeneous mixtures of metal powder or a mixture of metal powders or a ceramic powder or a mixture of ceramic powders and at least one binding agent are prepared in accordance with the method steps a) through d) to produce a corresponding multiplicity of molded articles and a sealing segment.