Method for manufacturing an abradable plate and repairing a turbine shroud

Abstract

The invention also provides a method of preparing a turbine shroud (24, 26) for a turbomachine.

1 . A method for manufacturing an abradable plate for a turbomachine turbine shroud, the method comprising the following steps:
 preparing a mixture comprising a cobalt- or nickel-based metal powder and a powder based on a fluxing element;   depositing a layer of the powder mixture in a mold; and   making the abradable plate by subjecting the powder mixture layer to a method of SPS sintering; and   wherein at least two layers of the powder mixture are deposited in the mold, the two layers being spaced apart from each other by a chemically inert insert.   
     
     
         2 . A method according to  claim 1 , wherein the chemically inert insert comprises boron nitride or corundum. 
     
     
         3 . A method according to  claim 2 , wherein boron nitride forms an outer layer of the chemically inert insert. 
     
     
         4 . A method according to  claim 1 , wherein the fluxing element is silicon or boron. 
     
     
         5 . A method according to  claim 1 , wherein the powder mixture comprises a percentage by weight of the fluxing element that is less than or equal to 5% by weight. 
     
     
         6 . A method according to  claim 1 , wherein the mold is made of graphite, and wherein the SPS sintering is performed at a temperature higher than or equal to 800° C. 
     
     
         7 . A method according to  claim 1 , wherein the mold is made of tungsten carbide, and wherein the SPS sintering is performed at a temperature higher than or equal to 500° C. 
     
     
         8 . A repairing method for repairing a turbine shroud for a turbomachine, the method comprising the following steps:
 removing a damaged abradable coating; and   brazing onto the turbine shroud an abradable plate obtained in accordance with  claim 1 .   
     
     
         9 . A repairing method according to  claim 8 , wherein after the abradable plate has been brazed onto the turbine shroud, a free surface of the brazed abradable plate is machined.