Silicon Carbide Member Porosity Reduction via Boron Mediator
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Solution Overview
Problem
Continuous fiber-reinforced silicon carbide members produced by existing methods often contain 5 to 20 vol % pores, particularly when manufactured using the chemical vapor infiltration method, which can limit their mechanical properties and environmental resistance.
Innovation Solution
A continuous fiber-reinforced silicon carbide member is created by stacking a first composite material layer with silicon carbide fibers and a matrix of silicon carbide, and a second composite material layer with carbon fibers and a silicon carbide matrix, optionally with an intermediate layer and a coating material layer for enhanced mechanical and environmental performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the chemical vapor infiltration method is used to manufacture continuous fiber-reinforced silicon carbide member, then high purity silicon carbide ceramics with stoichiometric composition are formed, but 5 to 20 vol % pores remain in the structure
Solution Approach 1:
A boron-containing compound is introduced as an intermediary substance during the chemical vapor infiltration process. This compound reacts with silicon to form silicon boride, which fills the pores between fibers and modifies the matrix composition, thereby reducing porosity while maintaining stoichiometric silicon carbide formation
Solution Approach 2:
The composition parameters of the matrix are changed by incorporating boron (0.1-5.0 wt%) into the silicon carbide matrix. This compositional modification allows the matrix to fill pores more effectively and improves both mechanical properties and environmental resistance without compromising the stoichiometric nature of the silicon carbide
2Strength
If continuous fiber-reinforced silicon carbide member is produced to enhance toughness and fracture energy, then brittle fracture resistance improves, but porosity of 5 to 20 vol % reduces mechanical property and environmental resistance
Solution Approach 1:
The boron-containing compound serves as a mediator that transforms the porous structure into a denser structure by forming silicon boride phases in the pore regions, thereby preserving the fiber reinforcement benefits while eliminating the detrimental effects of porosity
Solution Approach 2:
The invention creates a composite matrix system consisting of silicon carbide with boron additions (forming silicon boride phases). This composite matrix structure combines the high strength of silicon carbide with the pore-filling and densifying effects of silicon boride, achieving both high toughness and low porosity
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 proposed structure and manufacturing method significantly improve the mechanical properties and environmental resistance of the silicon carbide member, reducing the likelihood of brittle fracture and enhancing its suitability for applications requiring high strength and durability.
Implementation Method 1
a matrix is formed among the fibers by a chemical vapor deposition method or a chemical vapor infiltration method
Implementation Method 2
the silicon carbide member has higher hardness and is more excellent in properties such as abrasion resistance, heat resistance, oxidation resistance, corrosion resistance
Data Source
AI summary
There are provided a continuous fiber-reinforced silicon carbide member and the like which allow sufficient improvement in a mechanical property and environmental resistance. The continuous fiber-reinforced silicon carbide member of an embodiment is a tubular shape and has a first composite material layer and a second composite material layer. In the first composite material layer, continuous fibers of silicon carbide are combined with a matrix of silicon carbide. In the second composite material layer, continuous fibers of carbon are combined with a matrix of silicon carbide. Then, the first composite material layer and the second composite material layer are stacked.