Density gradient in blade to reduce centrifugal load

1. A method comprising:

reducing potential stress of a centrifugal load on a blade for a gas turbine engine by manufacturing a density gradient in a ceramic matrix composite of the blade by infiltrating a porous fiber preform, wherein the density gradient includes a change in density between a blade root-end of the blade and a blade tip-end of the blade.

2. The method of claim 1 , wherein manufacturing the density gradient comprises varying a percentage of silicon carbide in the blade along a radial direction, wherein the radial direction is in a direction away from a point around which the blade is configured to rotate.

3. The method of claim 1 wherein manufacturing the density gradient comprises:

providing the porous fiber preform, the porous fiber preform comprising a preform root-end and a preform tip-end;

infiltrating the porous fiber preform with a chemical vapor matrix material;

infiltrating the porous fiber preform with a ceramic-containing slurry; and

infiltrating the porous fiber preform with a ceramic-containing melt material.

4. The method of claim 3 wherein infiltrating with the chemical vapor matrix material comprises exposing the chemical vapor matrix material to the preform root-end at a first partial pressure that is greater than a second partial pressure of the chemical vapor matrix material applied to the preform tip-end.

5. The method of claim 4 further comprising arranging the porous fiber preform within a chemical vapor infiltration mask having a plurality of chemical vapor inlets including a first inlet and a second inlet, wherein the first inlet is larger than the second inlet, wherein the first inlet is located closer to the preform root-end of the porous fiber preform than to the tip-end, wherein the second inlet is located closer to the preform tip-end than to the preform root-end.

6. The method of claim 4 wherein infiltrating with the chemical vapor matrix material comprises heating the preform root-end to create a temperature differential between the preform root-end and the preform tip-end.

7. The method of claim 5 wherein infiltrating the porous fiber preform with a ceramic-containing slurry material comprises exposing the preform root-end in a first amount of ceramic-containing slurry that is greater than a second amount of ceramic-containing slurry applied to the preform tip-end.

8. The method of claim 7 further comprising applying a slurry infiltration mask to a portion of the tip-end of the porous fiber preform before infiltrating the porous fiber preform with the ceramic-containing slurry, and removing the slurry infiltration mask from the porous fiber preform.

9. The method of claim 8 wherein the slurry infiltration mask comprises a plurality of slurry inlets.

10. The method of claim 2 wherein manufacturing the density gradient comprises:

providing the porous fiber preform, the porous fiber preform comprising a preform root-end and a preform tip-end;

infiltrating the porous fiber preform with a chemical vapor matrix material;

infiltrating the porous fiber preform with a ceramic-containing slurry material;

applying a high-char yielding resin to the tip-end of the porous fiber preform in a first amount that is greater than a second amount of the high-char yielding resin applied to the preform root-end of the porous fiber preform;

pyrolyzing the high-char yielding resin by which a silicon carbon gradient is formed; and

forming the density gradient in the ceramic matric composite by infiltrating the porous fiber preform with a ceramic-containing melt material, which forms a silicon carbide gradient.

11. The method of claim 10 further comprising infiltrating the porous fiber preform with a ceramic-containing melt material.

12. The method of claim 1 wherein manufacturing the density gradient comprises:

providing the porous fiber preform, the porous fiber preform comprising a preform root-end and a preform tip-end;

infiltrating the porous fiber preform with a chemical vapor matrix material comprising at least one metal;

infiltrating the porous fiber preform with a metal-containing slurry; and

infiltrating the porous fiber preform with a metal-containing melt material.

13. The method of claim 1 wherein manufacturing the density gradient comprises:

providing the porous fiber preform, the porous fiber preform comprising a preform root-end and a preform tip-end;

infiltrating the porous fiber preform with a chemical vapor matrix material; and

infiltrating the porous fiber preform with a ceramic-oxide containing slurry.

14. A method of manufacturing a blade for a gas turbine engine with a density gradient between a blade root-end of the blade and a blade tip-end of the blade, the method comprising:

providing a porous preform comprising a preform root-end and a preform tip-end;

infiltrating the porous preform with a chemical vapor matrix material;

applying a slurry infiltration mask to a portion of the tip-end of the porous preform infiltrating the porous preform with a ceramic-containing slurry; and

removing the slurry infiltration mask from the porous preform.

15. The method of claim 14 wherein the slurry infiltration mask comprises a plurality of slurry inlets.

16. An apparatus comprising:

a blade for a gas turbine engine comprising a blade root-end and a blade tip-end, wherein a ceramic matrix composite of the blade has a density gradient, wherein the density gradient includes a change in density between a blade root-end of the blade and a tip-end of the blade, wherein a rate of change in density is constant along the density gradient.

17. The apparatus of claim 16 wherein the blade is a compressor blade.

18. The apparatus of claim 16 wherein the blade is a turbine blade.

19. The apparatus of claim 16 wherein the blade is contiguous along a longitudinal axis of the blade and further comprises a blade root-end chemical composition and a blade tip-end chemical composition wherein the blade root-end composition transitions into the blade tip-end composition.