Localized particle additions to reduce defects in ceramic matrix composites caused by complex geometry preforming
A method of forming a ceramic matrix composite component includes forming a fiber preform, the fiber preform including a plurality of ceramic fiber plies, a non-reduced fiber region having an areal weight, and a reduced fiber region characterized by a reduced areal weight less than the areal weight of the non-reduced fiber region by at least 5 percent. The method further includes selectively applying ceramic particles to the reduced fiber region in such manner as to avoid applying the ceramic particles to the non-reduced fiber region, and subsequently densifying the preform.
1. A method of forming a ceramic matrix composite component, the method comprising:
forming a fiber preform, the preform comprising:
a plurality of ceramic fiber plies;
a non-reduced fiber region having an areal weight; and
a reduced fiber region characterized by a reduced areal weight less than the areal weight of the non-reduced fiber region by at least 5 percent, the reduced fiber region further characterized as a gap between ceramic fibers within one of the plurality of ceramic fiber plies or ceramic fibers within adjacent ones of the plurality of ceramic fiber plies;
masking the non-reduced fiber region;
selectively applying ceramic particles to the reduced fiber region of the preform in such manner as to avoid applying the ceramic particles to the non-reduced fiber region, such that a resulting areal weight in the reduced fiber region is increased, thereby reducing a deviation in areal weight and a deviation in density between the reduced fiber region and the non-reduced fiber region; and
subsequently densifying the preform.
2. The method of claim 1 , wherein the ceramic fiber plies are formed from silicon carbide fibers.
3. The method of claim 1 , wherein the reduced fiber region corresponds to one of:
a curved region; and
a gap between adjacent ones of the plurality of plies.
4. The method of claim 1 , wherein a size of the ceramic particles ranges from 10 micrometers to 25 micrometers.
5. The method of claim 4 , wherein the step of selectively applying the ceramic particles comprises applying an aqueous suspension of the ceramic particles to the reduced fiber region.
6. The method of claim 5 and further comprising: applying the aqueous suspension as droplets.
7. The method of claim 5 , wherein the aqueous suspension comprises one of:
poly-vinyl butyral with ethanol; and
poly-vinyl alcohol.
8. The method of claim 1 , wherein a size of the ceramic particles ranges from 30 micrometers to 65 micrometers.
9. The method of claim 8 , wherein the step of selectively applying the ceramic particles comprises spraying the ceramic particles onto the reduced fiber region.
10. The method of claim 1 , wherein the step of masking the non-fiber reduced region comprises one of:
applying a stationary mask over the non-reduced fiber region; and
applying a mask attached to an applicator of the ceramic particles.
11. The method of claim 1 , wherein the step of densifying the fiber preform comprises one of a chemical vapor infiltration and a chemical vapor deposition process.
12. The method of claim 1 , wherein the ceramic particles are formed from a material selected from the group consisting of silicon carbide, silicon nitride, pure silicon, boron carbide, pure carbon, aluminum oxide, hafnia, and combinations thereof.
13. The method of claim 1 , wherein the reduced fiber region is a gap defined by a joint between adjacent ones of the plurality of ceramic fiber plies.
14. The method of claim 1 , wherein the reduced fiber region is a curved region of the preform wherein one or more plies of the plurality of ceramic fiber plies are bent.