Repair of directionally solidified alloys
A method for epitaxial addition of repair material onto a process surface ( 38 ) of a directionally solidified component ( 30 ). The component is positioned in a fluidized bed ( 34 ) to drift particles of a repair material over the process surface as laser energy ( 36 ) is rastered across the surface to melt the particles and to fuse repair material onto the entire surface simultaneously. The component is moved downward ( 39 ) in the bed in a direction parallel to the grain orientation in the component as material is added to the surface, thereby providing continuous epitaxial addition of material to the surface without recrystallization.
1. A method for epitaxial additional of repair material to a surface of a directionally solidified substrate material, the method comprising:
mobilizing a continuous supply of particles of repair material onto an entire process surface of the substrate material;
applying energy across the entire process surface in a manner effective to melt and fuse the repair material epitaxially onto the entire process surface simultaneously under a continuous condition of melting and solidification and not being rebuilt incrementally across the surface with individually solidified passes of progression, such that a solidification process interface of the fused particles progresses in a direction parallel to a grain orientation direction of the substrate material; and
providing relative motion between the continuous supply of repair material particles, a source of the energy, and the substrate material effective to maintain conditions for the continuous epitaxial addition of the repair material at the solidification process interface until a desired thickness of the repair material is added.
2. The method of claim 1 , wherein the step of mobilizing a continuous supply of repair material particles comprises disposing the substrate material in a fluidized bed of the repair material particles.
3. The method of claim 2 , further comprising using an inert gas as a mobilizing fluid in the fluidized bed.
4. The method of claim 1 , wherein the step of mobilizing a continuous supply of repair material particles comprises applying the repair material particles by a broadcast spray.
5. The method of claim 1 , wherein the step of mobilizing a continuous supply of repair material particles comprises vibrating the substrate material.
6. The method of claim 1 , wherein the step of mobilizing a continuous supply of repair material particles comprises disposing the substrate material in a bed of the repair material particles and vibrating the bed.
7. The method of claim 1 , wherein the step of applying energy comprises rastering a laser beam across the entire process surface.
8. The method of claim 1 , wherein the step of applying energy comprises directing laser energy through optics to the entire process surface simultaneously.
9. The method of claim 1 , wherein the step of providing relative motion comprises lowering the substrate material relative to a particle surface in a fluidized bed of the particles of repair material.
10. The method of claim 9 , further comprising using an inert gas as a mobilizing fluid in the fluidized bed.
11. The method of claim 1 used to add material to a squealer tip of a gas turbine blade formed of directionally solidified superalloy material.
12. A method for repair of a directionally solidified gas turbine engine component, the method comprising:
disposing the component in a fluidized bed of repair material particles;
activating the fluidized bed to mobilize movement of a flow of the particles onto a repair surface of the component;
rastering laser energy across the repair surface to melt and fuse particles epitaxially onto the entire repair surface simultaneously under a continuous condition of melting and solidification and not being rebuilt incrementally across the surface with individually solidified passes of progression, such that a solidification process interface of the fused particles progresses along an axis parallel to a grain orientation direction of the component; and
moving the component downward in the fluidized bed along the axis as the solidification process interface progresses to maintain a continuous epitaxial extension of grain microstructure on the component.
13. The method of claim 12 applied to repair a squealer tip of a gas turbine blade.
14. The method of claim 12 , further comprising using an inert gas as a mobilizing fluid in the fluidized bed.
15. A method for epitaxial additional of material to a surface of a directionally solidified substrate, the method comprising:
mobilizing particles of material over a process surface of the substrate;
applying energy across the entire process surface in a manner effective to melt and fuse the material epitaxially onto the entire process surface simultaneously under a continuous condition of melting and solidification and not being rebuilt incrementally across the surface with individually solidified passes of progression; and
maintaining the substrate in a position relative to the particles of material and the applied energy effective to maintain conditions for continuous epitaxial addition of the material to the substrate until a desired thickness of the material is added.
16. The method of claim 15 , further comprising mobilizing the particles of material in a fluidized bed to drift the particles onto the process surface.
17. The method of claim 16 , further comprising lowering the substrate in the fluidized bed as the material is added to the substrate to maintain a position of the process surface relative to a surface of the particles in the fluidized bed.
18. The method of claim 17 , further comprising applying the energy by rastering a laser beam across the process surface in a continuous manner.
19. The method of claim 18 , further comprising using an inert gas as the mobilizing fluid in the fluidized bed.