Sol-Gel Impregnation for Ceramic Composite Porosity Control
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Solution Overview
Problem
Current methods for producing fiber-reinforced composite materials require post-treatment infiltration to reduce porosity, making them time-consuming and costly, and often result in materials with residual carbon that are not thermally or oxidatively stable for long-term applications.
Innovation Solution
A method involving impregnation of ceramic fibers with a sol-gel slip, followed by freezing and sintering, which eliminates the need for post-treatment infiltration and produces a thermally stable, oxidation-resistant composite material with controlled porosity, using an aqueous suspension with nanoparticles and a filler to form a gel that maintains material integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If post-treatment infiltration is used to reduce porosity, then material density and strength are improved, but production time and cost increase
Solution Approach 1:
The patent applies preliminary action by forming a gel structure during the sintering process itself, rather than requiring subsequent infiltration treatment. The gel-forming agents create a matrix structure in advance that fills pores and binds fibers, eliminating the need for post-treatment infiltration while achieving the desired material density and strength.
Solution Approach 2:
The patent changes the chemical and physical parameters of the sintering process by introducing gel-forming agents that undergo phase transformation during sintering. This parameter change allows the matrix to form with appropriate density and binding properties directly during sintering, avoiding the need for additional infiltration steps to improve material strength.
2Ease of manufacture
If traditional sintering is used, then production process is simple, but material contains residual carbon that reduces thermal and oxidative stability
Solution Approach 1:
The patent changes the chemical composition parameters of the sintering mixture by adding gel-forming agents that decompose to form stable ceramic matrices. This parameter change transforms the sintering process from producing carbon-containing materials to producing thermally stable and oxidation-resistant ceramic composites, while maintaining relatively simple manufacturing procedures.
Solution Approach 2:
The patent creates a composite material system combining fibers with gel-forming agents that produce a stable ceramic matrix upon sintering. This composite approach eliminates residual carbon issues while maintaining process simplicity, as the gel-forming agents integrate seamlessly into the existing sintering workflow.
3Manufacturing precision
If porosity is reduced through infiltration, then material density improves, but additional processing steps and costs are incurred
Solution Approach 1:
The patent applies preliminary action by pre-forming the gel structure that will become the matrix during sintering. This preliminary gel formation ensures proper porosity control and material density are achieved during the sintering process itself, eliminating the need for subsequent infiltration steps and reducing overall process complexity.
Solution Approach 2:
The patent utilizes phase transitions of gel-forming agents during sintering to control porosity and density. The gel-to-ceramic phase transformation occurs in-situ during sintering, creating a dense matrix structure without requiring additional infiltration equipment or processing steps, thus maintaining manufacturing precision while simplifying the overall process.
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 produces fiber-reinforced composite materials that are thermally stable, oxidation-resistant, and long-term stable, eliminating the need for infiltration and reducing material defects, suitable for high-temperature applications in industries like aviation and space exploration.
Implementation Method 1
c) freezing the product obtained in step b)
Implementation Method 2
with said suspension comprising nanoparticles, at least one filler with a particle size of at least 1 μm and optionally a dispersing agent
Implementation Method 3
d) heating the product obtained in step c) to produce a green body
Implementation Method 4
heating the product obtained in step c) to produce a green body
Implementation Method 5
e) sintering the product obtained in step d), preferably after removing the support
Data Source
Figure 1a~1b
Figure 1c
Figure 2~3
AI summary
The invention relates to a method for producing components from a fiber-reinforced composite material and to the use of said components in industry, astronautics, or aeronautics. The method according to the invention has a sol-gel process using freeze gelation. For this purpose, a continuous fiber, preferably an oxide ceramic fiber, is impregnated with a sol-gel slurry and applied onto a substrate prior to the freeze gelation preferably in the winding process. The thus obtained green body is sintered in the subsequent method step.