Porous Core for Ceramic Matrix Composite Distributor
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Solution Overview
Problem
Conventional solid cores used in the production of ceramic matrix composite distributors hinder gas circulation during chemical vapor infiltration, leading to uneven deposition of boron nitride and silicon carbide, which results in insufficient mechanical properties and susceptibility to mechanical stress.
Innovation Solution
A core with fluid passages within its transverse thickness, allowing gas circulation from one face to the other, ensuring homogeneous deposition of BN and SiC, and preventing diffusion gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a solid core with continuous surface is used, then the core provides structural support and resists high temperatures, but it blocks gas circulation and disrupts boron nitride deposition
Solution Approach 1:
The core is designed with a porous structure containing numerous fluid passages distributed throughout its volume. This porous configuration allows gases to circulate freely through the core during CVI cycles, enabling uniform boron nitride deposition on all surfaces of the fibrous preform while the core itself maintains its structural support function.
Solution Approach 2:
The core is segmented into multiple functional zones with fluid passages distributed throughout. Instead of a continuous solid structure, the core is divided into numerous discrete fluid passage channels that are interconnected, allowing gas flow from one side of the core to the other while maintaining structural integrity.
2Stability of the object's composition
If a solid core is used, then the core maintains structural integrity during CVI cycles, but it creates diffusion gradients that reduce BN layer thickness
Solution Approach 1:
The porous structure with distributed fluid passages eliminates diffusion gradients by enabling direct gas flow through the core. Gases can reach all surfaces of the fibrous preform uniformly, ensuring consistent boron nitride deposition thickness throughout the entire component while the core maintains structural stability.
3Strength
If a solid core is used, then the core provides mechanical support, but it prevents adequate SiC slurry deposition and allows liquid silicon to attack BN
Solution Approach 1:
The porous core structure allows adequate SiC slurry deposition by enabling proper fluid distribution throughout the core. The fluid passages ensure that slurry reaches all surfaces uniformly, creating sufficient BN layer thickness that protects against liquid silicon attack during densification, thereby maintaining mechanical properties.
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
The core design enhances the mechanical performance of ceramic matrix composite parts by achieving a suitable thickness of BN and SiC, improving thermal performance, and maintaining mechanical properties during densification.
Implementation Method 1
The fibrous preform is densified during a step of chemical vapor deposition of boron nitride (BN). This step is called 'Chemical Vapor Infiltration' (CVI), and several cycles are carried out.
Implementation Method 2
As illustrated in FIG. 1, the conventional cores 2 employed have a solid structure: they are solid with a continuous surface and completely fill the cavity. This configuration blocks the passage of gases, which do not travel through the core from one side to the other.
Data Source
AI summary
A core for producing a blade is formed by molding a fibrous preform around the core. The core extends in a longitudinal direction (L) between a root and a tip and has a first face and a second face connected to each other at a first longitudinal edge and at a second longitudinal edge. The core includes fluid passages formed in a transverse thickness of the core, these fluid passages being adapted to allow the passage of fluid from the first face to the second face and vice versa.