Controlled gradient of porosity in CMC

A ceramic matrix composite preform comprising:

• a plurality of first ceramic fiber plies and a plurality of second ceramic fiber plies, wherein each of the plurality of first ceramic fiber plies comprises a plurality of first interconnected tows and the plurality of second ceramic fiber plies comprises a plurality of second interconnected tows;
• a first zone comprising at least one of the first ceramic fiber plies and a plurality of first pores positioned between adjacent tows within the first zone, wherein the plurality of first pores have a first average pore size and the plurality of first pores include a plurality of first ceramic particles positioned within the plurality of first pores during a first pre-impregnation operation;
• and
• a second zone comprising at least one of the second ceramic fiber plies and a plurality of second pores positioned between adjacent tows within the second zone, wherein the plurality of second pores have a second average pore size and the plurality of second pores include a plurality of second ceramic particles positioned within the plurality of second pores during a second pre-impregnation operation;
• wherein each of the plurality of second ceramic particles are larger than each of the plurality of first ceramic particles;
• wherein a planar porosity of the first zone with the plurality of first ceramic particles positioned within the plurality of first pores is lower than a planar porosity of the second zone with the plurality of second ceramic particles positioned within the plurality of second pores;
• wherein the planar porosity of the first zone is a percentage of pore area relative to a total area of the at least one of the first ceramic fiber plies in the first zone measured within a plane intersecting with the at least one of the first ceramic fiber plies in the first zone and the planar porosity of the second zone is a percentage of pore area relative to a total area of the at least one of the second ceramic fiber plies in the second zone intersecting with the at least one of the second ceramic fiber plies in the second zone.