Turbine blade tip with optimized abrasive

Abstract

A new abrasive blade tip treatment is disclosed with the potential to provide improved blade tip clearance control in the turbine section of modern industrial gas turbines (IGT's). This blade tip treatment is composed of a unique combination of abrasive compounds that result in improved resistance to thermal degradation while retaining desirable initial cutting capacity.

1 . A turbine blade with abrasive tip coating, comprising: 
 an elongated turbine blade having a tip at one end, said tip having an abrasive coating including a mixture of cubic boron nitride and silicon nitride.    
     
     
         2 . The turbine blade according to  claim 1  wherein the abrasive coating includes a substantially 50:50 mixture of cubic boron nitride and silicon nitride.  
     
     
         3 . The turbine blade according to  claim 1  wherein the abrasive coating includes a super alloy of at least one of nickel and cobalt.  
     
     
         4 . The turbine blade according to  claim 3  wherein the super alloy is CoNiCrAlY.  
     
     
         5 . The turbine blade according to  claim 3  wherein the abrasive coating includes a substantially 50:50 mixture of cubic boron nitride and silicon nitride.  
     
     
         6 . The turbine blade according to  claim 1  wherein the cubic boron nitride and the silicon nitride are electroplated to the blade tip.  
     
     
         7 . A turbine blade and ring segment assembly, comprising: 
 a turbine ring segment having an abradable coating on an inner surface thereof; 
 an elongated turbine blade having a tip at one end, said blade tip having an abrasive coating, said abrasive coating engaging and abrading said abradable coating of the turbine ring segment; wherein said abrasive coating of said blade tip includes a mixture of cubic boron nitride and silicon nitride.  
   
     
     
         8 . The assembly according to  claim 7  wherein the abrasive coating includes a substantially 50:50 mixture of cubic boron nitride and silicon nitride.  
     
     
         9 . The assembly according to  claim 7  wherein the abrasive coating includes a super alloy of at least one of nickel and cobalt.  
     
     
         10 . The assembly according to  claim 9  wherein the super alloy is CoNiCrAlY.  
     
     
         11 . The assembly according to  claim 9  wherein the abrasive coating includes a substantially 50:50 mixture of cubic boron nitride and silicon nitride.  
     
     
         12 . The assembly according to  claim 7  wherein the cubic boron nitride and the silicon nitride are electroplated to the blade tip.  
     
     
         13 . The assembly according to  claim 7  wherein the abradable material of the ring segment is a thermal barrier coating.  
     
     
         14 . The assembly according to  claim 13  wherein the thermal barrier coating is porous.  
     
     
         15 . The assembly according to  claim 14  wherein the thermal barrier coating is ceramic.  
     
     
         16 . The assembly according to  claim 15  wherein the thermal barrier coating includes yttria-stabilized zirconia (YSZ).  
     
     
         17 . The assembly according to  claim 16  wherein the thermal barrier coating includes 8 wt. % YSZ (8YSZ).