Fiber Preform Machining for CMC Fabrication
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Solution Overview
Problem
The preforming process for ceramic matrix composites, particularly for complex shapes, is energy intensive and time consuming, and requires precise cutting and laying up of plies with slight size and shape differences, posing logistical challenges.
Innovation Solution
A method utilizing a fugitive binder and machining step, where plies are laid up in simple geometries, infiltrated with a polymer, and then machined to form a rigid fiber preform, which is subsequently pyrolyzed to create a porous preform of predetermined geometry for further processing into a CMC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If traditional preforming process is used to fabricate CMC components of complex shapes, then the desired geometry can be achieved, but the process becomes energy intensive and time consuming
Solution Approach 1:
The patent applies preliminary action by pre-assembling fiber plies into simple geometric stacks before infiltration. The plies are arranged in basic configurations (flat stacks, curved stacks) that can be easily manufactured, then later transformed into complex final geometries through the infiltration and pyrolysis process, avoiding the need to manually cut and position each ply to its final complex shape
2Shape
If traditional preforming process is used to fabricate CMC components of complex shapes, then the desired geometry can be achieved, but the process becomes time consuming
Solution Approach 1:
The patent applies preliminary action by pre-assembling fiber plies into simple geometric stacks before infiltration. The plies are arranged in basic configurations (flat stacks, curved stacks) that can be easily manufactured, then later transformed into complex final geometries through the infiltration and pyrolysis process, avoiding the need to manually cut and position each ply to its final complex shape
Solution Approach 2:
The patent merges multiple operations into fewer steps. Instead of separately cutting, positioning, and assembling each ply to its final complex shape, the process combines ply stacking with simple geometric forms, then merges the shaping function into the infiltration and pyrolysis stages, significantly reducing the number of discrete manufacturing operations
3Manufacturing precision
If each ply is cut to proper dimensions and laid up in correct location and orientation for complex shapes, then the desired precision can be achieved, but logistical challenges increase
Solution Approach 1:
The patent applies preliminary action by pre-assembling fiber plies into simple geometric stacks before infiltration. The plies are arranged in basic configurations (flat stacks, curved stacks) that can be easily manufactured, then later transformed into complex final geometries through the infiltration and pyrolysis process, avoiding the need to manually cut and position each ply to its final complex shape
Solution Approach 2:
The patent uses the polymer infiltration material as an intermediary that facilitates the transformation from simple stack geometries to complex final shapes. The infiltrating polymer fills and bonds the fiber stacks, enabling geometric transformation without requiring precise manual positioning of individual plies during assembly
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the preforming process by avoiding the complexity of cutting and laying up individual plies, achieving higher dimensional accuracy and enabling the formation of complex geometries with reduced energy and time consumption.
Implementation Method 1
The stack is infiltrated with a polymer at an elevated temperature to form an infiltrated stack
Implementation Method 2
The infiltrated stack is cooled to form a rigid fiber preform
Implementation Method 3
the composite assembly is heated at a sufficient temperature to pyrolyze the polymer. Thus, a porous preform of a predetermined geometry is formed
Data Source
AI summary
A method of making a fiber preform for ceramic matrix composite (CMC) fabrication that utilizes a fugitive binder and a machining step is described. The method includes, according to one embodiment, laying up a plurality of plies to form a stack, where each ply comprises an arrangement of fibers. The stack is infiltrated with a polymer at an elevated temperature to form an infiltrated stack that is cooled to form a rigid preform. The rigid fiber preform is machined to have a predetermined shape, such that a machined fiber preform is formed. A composite assembly including the machined fiber preform is formed and then the composite assembly is heated at a sufficient temperature to pyrolyze the polymer. Thus, a porous preform of a predetermined geometry is formed for further processing into a CMC.