Ceramic Matrix Composite Articles with Segmented CVI and MI
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for forming ceramic matrix composites (CMCs) face limitations in achieving efficient integration of chemical vapor infiltration (CVI) and melt infiltration (MI) processes, leading to high residual porosity, temperature limitations, and compromised mechanical and thermal properties, particularly in high-temperature applications like gas turbines.
Innovation Solution
A method for forming CMC articles by simultaneously laying up and compacting groups of plies using CVI and MI processes, with tailored resin and powder compositions, to create a composite with distinct properties in different areas, enhancing mechanical and thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If melt infiltration (MI) is used to form CMC, then the composite achieves low residual porosity and high mechanical strength, but the use temperature is limited to below 1410°C due to free silicon phase
Solution Approach 1:
The CMC article is divided into two distinct portions: a first portion formed by CVI with no free silicon phase for high-temperature regions, and a second portion formed by MI with low porosity for mechanical strength requirements. This segmentation allows each portion to optimize for its specific functional requirements without compromise.
Solution Approach 2:
Different regions of the CMC article are赋予 different material properties: the first portion has CVI matrix with properties optimized for high-temperature creep resistance, while the second portion has MI matrix with properties optimized for low porosity and mechanical strength. Each local region has quality tailored to its operational requirements.
2Temperature
If chemical vapor infiltration (CVI) is used to form CMC, then the composite achieves better creep resistance and higher operating temperature capability, but residual porosity increases to 10-15%
Solution Approach 1:
The CMC article is divided into two distinct portions: a first portion formed by CVI with no free silicon phase for high-temperature regions, and a second portion formed by MI with low porosity for mechanical strength requirements. This segmentation allows each portion to optimize for its specific functional requirements without compromise.
Solution Approach 2:
Different regions of the CMC article are赋予 different material properties: the first portion has CVI matrix with properties optimized for high-temperature creep resistance, while the second portion has MI matrix with properties optimized for low porosity and mechanical strength. Each local region has quality tailored to its operational requirements.
3Reliability
If CVI and MI processes are performed sequentially to form mixed CMC articles, then both high-temperature capability and low porosity are achieved, but processing time becomes prohibitively long
Solution Approach 1:
The patent combines CVI and MI processes into a single integrated manufacturing step, where both chemical vapor infiltration and melt infiltration occur simultaneously or in a continuous sequence without intermediate handling. This merging eliminates the time-consuming sequential approach while achieving both low porosity and high-temperature capability in the final composite.
Solution Approach 2:
The fiber preform is prepared with specific characteristics (such as controlled porosity distribution and fiber arrangement) before the combined CVI-MI process, enabling both infiltration mechanisms to proceed efficiently in a single operation. The preliminary preparation of the preform structure facilitates the simultaneous or continuous infiltration processes.
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 method results in a CMC article capable of withstanding high temperatures while maintaining desirable mechanical properties, offering improved creep resistance and thermal conductivity, and reducing processing time compared to traditional sequential methods.
Implementation Method 1
pyrolyzing the preform in the same processing step
Implementation Method 2
passing a first group of tows through a first slurry including a resin and silicon carbide powder added thereto
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method for forming a ceramic matrix composite article includes laying up (410) a first group of plies; laying up (412) a second group of plies, the first and second groups of plies being adjacent to each other; compacting (414) the first group of plies and the second group of plies in the same processing step; and performing (420) a first infiltration process on the first group of plies. The method also includes performing (422) a second infiltration process on the second group of plies, the first infiltration process being one of a melt infiltration process or a chemical vapor infiltration process, and the second infiltration process being the other of the melt infiltration process or the chemical vapor infiltration process.