Ceramic Matrix Composite Cooling Circuit Fabrication

The patent applies preliminary action by forming holes in the fiber sheets during the preform fabrication stage, before matrix infiltration. Mandrels with openings are used to create holes in each fiber sheet that will become the cooling channels after assembly. This preliminary formation of cooling channel structures eliminates the need for post-fabrication drilling or machining, which would be difficult in dense ceramic composites.

The patent segments the cooling channel formation process into discrete steps: forming holes in individual fiber sheets using mandrels, then assembling multiple sheets with aligned holes. This segmentation allows each sheet to be prepared independently with precise hole placement, and the holes are then fluidly connected through proper alignment during assembly, creating the complete internal cooling circuit.

The patent merges the cooling channel formation process with the composite fabrication process itself. The same mandrels and fiber sheet handling used to create the composite structure are also used to form the cooling channels. The holes are created in the fiber sheets during assembly, and the matrix infiltration process simultaneously binds the fibers and preserves the hollow channels, combining two functions into one integrated process.

The patent uses mandrels with openings as intermediaries to transfer the cooling channel geometry from the tooling to the final component. The mandrels are temporarily introduced during fabrication, their openings define the hole positions and shapes in the fiber sheets, and the mandrels are later removed to leave the desired cooling channels. This intermediary approach simplifies the overall process compared to direct drilling or machining.

The patent performs hole formation in the fiber sheets during the preform fabrication stage, which is a necessary step anyway to assemble the composite structure. By combining cooling channel formation with preform assembly, the patent avoids adding separate post-fabrication steps for channel creation. The holes are formed while the structure is still being built, making the most of the existing process sequence.

The patent combines multiple operations into the preform fabrication step: fiber sheet placement, hole formation using mandrels, alignment of holes between sheets, and matrix infiltration all occur in an integrated sequence. This merging eliminates the need for separate drilling, machining, or channel formation steps that would extend the fabrication cycle, maintaining productivity while adding cooling functionality.