Ceramic Matrix Composite Preform Densification Using ALD Layers
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Solution Overview
Problem
Existing methods for producing ceramic matrix composite (CMC) components with low porosity and high temperature resistance, such as those used in gas turbine engines, face challenges like residual porosity, microcracking, and high costs due to lengthy processes like CVI and PIP.
Innovation Solution
The method involves producing a porous preform with ceramic constituents and applying one or more layers of material using atomic layer deposition (ALD) to decrease porosity, followed by additional layers applied through time-dependent or non-self-limiting deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical vapor infiltration (CVI) process is used to produce CMC components, then the component can be formed with ceramic matrix, but the process is lengthy and expensive and suffers from inadequate densification due to canning off
Solution Approach 1:
The invention segments the densification process into multiple sequential infiltration cycles, each depositing a thin layer of material. This allows progressive densification without the canning off problem that occurs in single-step processes, as each thin layer can be uniformly deposited before the next cycle begins.
Solution Approach 2:
The invention employs periodic infiltration cycles with alternating deposition and consolidation phases. This periodic action allows the material to be deposited in controlled increments, preventing pore closure issues while maintaining continuous progress toward complete densification.
2Volume of moving object
If chemical vapor infiltration (CVI) process is used to apply thick CVI layer, then the layer thickness is increased, but the process cost and time increase significantly
Solution Approach 1:
The invention maintains continuous useful action by implementing overlapping infiltration cycles where subsequent cycles begin before previous ones are completely finished. This continuous approach builds up thick layers efficiently without the idle time between complete cycles, significantly reducing total process time while achieving the desired thickness.
Solution Approach 2:
The invention performs preliminary infiltration actions that prepare the substrate for subsequent thicker deposits. By pre-treating the surface and creating initial nucleation sites, the process enables faster and more efficient deposition of thick layers in later cycles, reducing the overall time required.
3Quantity of substance
If CVI process is used for densification, then material deposition is achieved, but fiber tows and regions are sealed off from further densification
Solution Approach 1:
The invention applies partial infiltration actions in each cycle, depositing only thin layers that do not completely fill the pore structure. This partial action prevents pore closure while allowing subsequent cycles to access previously unreachable regions, ensuring uniform densification throughout the entire component including deep interior areas.
Solution Approach 2:
The invention transitions from thinking about densification in terms of total thickness to considering it in terms of cumulative thin layers across multiple dimensions of time and space. This dimensional approach allows material to reach into fiber tows and complex geometries through the incremental buildup of many thin layers rather than attempting to deposit thick material in a single step.
4Reliability
If hybrid CVI/PIP process is used, then densification is improved, but residual void space remains due to canning off
Solution Approach 1:
The invention systematically changes process parameters including temperature, pressure, and precursor flow rates across different infiltration cycles. These parameter variations prevent the conditions that lead to canning off by adjusting the deposition kinetics, allowing continuous penetration into the pore structure and eliminating residual void space while maintaining high densification quality.
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 enables the production of CMC components with significantly reduced porosity and improved densification, enhancing their thermal and mechanical properties for high-temperature applications.
Implementation Method 1
applying at least one layer of a first material to the preform using an atomic layer deposition (ALD) process to decrease a porosity of the preform
Implementation Method 2
applying one or more layers of a second material to the preform using a deposition process that deposits the second material in a time dependent or non-self-limiting process, wherein the deposition process is at least one of a chemical vapor infiltration process
Implementation Method 3
a polymer infiltration and pyrolysis (PIP) process
Data Source
AI summary
A method of producing a ceramic matrix composite material component is provided. The method includes that steps of: a) producing a preform having one or more ceramic constituents, the preform being porous with internal voids; and b) applying at least one layer of a first material to the preform using an atomic layer deposition (ALD) process to decrease a porosity of the preform.