Seal-less CMC vane to platform interfaces

1. A stator vane assembly for a gas turbine comprising a ceramic matrix composite airfoil held between radially inner and outer metal platforms wherein a seal-less interface between said airfoil and at least one of said radially inner and outer platforms is shaped to create a circuitous leakage path for gas from the gas turbine.

2. The stator vane assembly of claim 1 wherein said interface comprises mating stepped surfaces.

3. The stator vane assembly of claim 2 wherein said mating stepped surfaces include at least two steps perpendicular to a radial centerline through said vane.

4. The stator vane assembly of claim 1 wherein said interface comprises a mating scarf joint.

5. The stator vane assembly of claim 4 wherein said scarf joint includes mating surfaces at an angle of about 45° relative to a radial centerline through said vane.

6. The stator vane assembly of claim 1 wherein said interface comprises plural abradable knife edges on said radially inner platform adjacent a smooth surface on said airfoil.

7. The stator vane assembly of claim 6 wherein said plural abradable knife edges comprise at least four projections terminating in radial surfaces adjacent said smooth surface on said airfoil.

8. The stator vane assembly of claim 1 wherein said interface is located at said radially inner platform.

9. A stator vane assembly for a gas turbine comprising a ceramic matrix composite airfoil held in seal-less fashion between radially inner and outer metal platforms wherein at least one of said platforms is formed with a recess adapted to receive said airfoil, said recess including a peripheral edge, said peripheral edge shaped to create a circuitous leakage path in cooperation with an adjacent surface on said airfoil.

10. The stator vane assembly of claim 9 wherein said adjacent airfoil surface is smooth.

11. The stator vane assembly of claim 9 wherein said peripheral edge is shaped to include a first plurality of steps and said adjacent surface on said airfoil is shaped to include a second plurality of complementary steps.

12. The stator vane assembly of claim 11 wherein said first plurality of steps include at least two steps perpendicular to a radial centerline through said vane.

13. The stator vane assembly of claim 9 wherein said peripheral edge is shaped to include a scarf joint comprising first angled surface and said adjacent surface on said airfoil is shaped to include a second complementary angled surface.

14. The stator vane assembly of claim 13 wherein said scarf joint includes mating surfaces at an angle of about 45° relative to a radial centerline through said vane.

15. The stator vane assembly of claim 9 wherein said peripheral edge comprises plural abradable knife edges on said radially inner platform adjacent a smooth surface on said airfoil.

16. A stator vane assembly for a gas turbine comprising a ceramic matrix composite vane held between radially inner and outer metal platforms wherein a seal-less interface between said vane and at least one of said radially inner and outer platforms is shaped to provide a compliant face for engagement with a smooth surface on said vane.

17. The stator vane assembly of claim 16 wherein at least said radially inner platform is formed with an inner recess, that receives said stator vane, said inner recess having a peripheral edge; and a plurality of oppositely directed radial slots adjacent said peripheral edge.

18. The stator vane assembly of claim 17 wherein said peripheral edge of said inner recess is also formed with a surface shaped to create a circuitous leakage path for gas from the gas turbine hot gas path.

19. The stator vane assembly of claim 18 wherein said edge comprises one of a stepped or angled surface adapted to engage a respective complementary stepped or angled surface on said ceramic matrix composite vane.