Methods for manufacturing a turbine nozzle with single crystal alloy nozzle segments

Abstract

Methods for manufacturing a turbine nozzle are provided. A plurality of nozzle segments is formed. Each nozzle segment comprises an endwall ring portion with at least one vane. The plurality of nozzle segments are connected to an annular endwall forming a segmented annular endwall concentric to the annular endwall with the at least one vane of each nozzle segment extending between the segmented annular endwall and the annular endwall.

1 . A method for manufacturing a turbine nozzle comprising:
 forming a plurality of nozzle segments, each nozzle segment comprising an endwall ring portion with at least one vane, the at least one vane having a free end portion;   connecting the free end portion of the at least one vane of each nozzle segment of the plurality of nozzle segments to an annular endwall, with the endwall ring portion of each nozzle segment of the plurality of nozzle segments forming a segmented annular endwall concentric to the annular endwall with the at least one vane of each nozzle segment extending between the segmented annular endwall and the annular endwall; and   forming the annular endwall prior to the connecting by separately casting the annular endwall as one-piece,   wherein the step of connecting the plurality of nozzle segments comprises brazing the free end portion of the at least one vane of each nozzle segment to the annular endwall.   
     
     
         2 . The method of  claim 1 , wherein the step of forming a plurality of nozzle segments comprises forming the plurality of nozzle segments with a single crystal material. 
     
     
         3 . The method of  claim 1 , wherein the step of forming a plurality of nozzle segments comprises forming by casting. 
     
     
         4 . The method of  claim 1 , wherein the step of forming a plurality of nozzle segments comprises forming a plurality of singlet nozzle segments, doublet nozzle segments, triplet nozzle segments, quadruplet nozzle segments, or combinations thereof. 
     
     
         5 . The method of  claim 1 , further comprising the step of processing at least one nozzle segment of the plurality of nozzle segments after the forming the plurality of nozzle segments and prior to the connecting step, wherein the step of processing comprises applying a protective coating to at least one nozzle segment of the plurality of nozzle segments, the annular endwall, or both. 
     
     
         6 . The method of  claim 1 , further comprising the step of processing at least one nozzle segment of the plurality of nozzle segments prior to the connecting step, wherein the step of processing comprises machining at least one cooling hole in at least one nozzle segment, machining a feather-seal slot in opposing ends of at least two nozzle segments for receiving an interlocking feather seal, or both. 
     
     
         7 . The method of  claim 1 , wherein the step of connecting the plurality of nozzle segments comprises circumferentially spacing the plurality of nozzle segments along the annular endwall with the endwall ring portion of each nozzle segment cooperating to form the segmented annular endwall. 
     
     
         8 . (canceled) 
     
     
         9 . The method of  claim 6 , further comprising the step of sealing the plurality of nozzle segments together during or after the connecting step, the step of sealing comprising inserting the interlocking feather seal into intersecting feather-seal slots machined into opposed end faces of the endwall ring portion of at least a pair of circumferentially adjacent nozzle segments. 
     
     
         10 . A method for manufacturing a turbine nozzle comprising:
 forming a plurality of nozzle segments configured to be connected to an outer annular endwall, each nozzle segment integrally cast as one piece from a single crystal alloy material and comprised of an endwall ring portion and at least one vane, the at least one vane having a free end portion;   brazing the free end portion of the at least one vane of each nozzle segment to the outer annular endwall, the endwall ring portion of each nozzle segment cooperating with the endwall ring portion of a circumferentially adjacent nozzle segment to form a segmented inner annular endwall concentric to the outer annular endwall with the at least one vane of each nozzle segment extending between the segmented inner annular endwall and the outer annular endwall, the brazing of the free end portion of the at least one vane of each nozzle segment to the outer annular endwall forming the turbine nozzle; and   forming the outer annular endwall prior to the brazing by separately casting the outer annular endwall as a one-piece ring.   
     
     
         11 . The method of  claim 10 , wherein the step of forming a plurality of nozzle segments comprises forming a plurality of singlet nozzle segments, doublet nozzle segments, triplet nozzle segments, quadruplet nozzle segments, or combinations thereof. 
     
     
         12 . The method of  claim 10 , further comprising the step of processing at least one nozzle segment of the plurality of nozzle segments after forming the plurality of nozzle segments and prior to brazing, wherein the step of processing comprises applying a protective coating to the at least one nozzle segment. 
     
     
         13 . The method of  claim 10 , further comprising the step of processing at least one nozzle segment of the plurality of nozzle segments prior to brazing, wherein the step of processing comprises machining at least one cooling hole in the at least one nozzle segment. 
     
     
         14 . The method of  claim 10 , further comprising the step of processing at least one nozzle segment of the plurality of nozzle segments prior to brazing, wherein the step of processing comprises machining a feather-seal slot in opposing end faces of the endwall ring portion of at least two nozzle segments for receiving an interlocking feather seal. 
     
     
         15 . The method of  claim 10 , further comprising the step of sealing the plurality of nozzle segments together during or after the connecting step, the step of sealing comprising inserting the interlocking feather seal into intersecting feather-seal slots machined into at least a pair of circumferentially adjacent nozzle segments.