Continuous ceramic fiber, method for producing the same, and ceramic matrix composite containing the continuous ceramic fiber
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Solution Overview
Problem
Continuous ceramic fibers with existing coatings, such as zirconia or rare-earth phosphates, experience reduced strength due to heat resistance treatment and thermal residual stress, leading to low single fiber strength.
Innovation Solution
A continuous ceramic fiber with a surface region containing at least one of ytterbium and lutetium, either as an inorganic acid salt or in the form of phosphate, silicate, nitrate, carbonate, or sulfate, which inhibits the deterioration of strength at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a coating layer of zirconia or lanthanum oxide is applied to improve heat resistance, then heat resistance is improved, but single fiber strength decreases due to heat resistance treatment
Solution Approach 1:
The patent changes the chemical composition parameters of the coating layer by selecting specific rare-earth elements (ytterbium or lutetium) with appropriate atomic radii and electronegativities. This parameter optimization allows the coating to maintain heat resistance while reducing the detrimental effects on fiber strength during heat treatment, achieving a balance between thermal stability and mechanical properties.
Solution Approach 2:
The patent creates a composite coating structure combining rare-earth elements with phosphate, silicate, nitrate, carbonate, or sulfate anions. This composite material approach leverages the synergistic effects of the rare-earth cations and anionic groups to provide both thermal protection and strength retention, overcoming the limitations of single-component coatings like zirconia or lanthanum oxide.
2Temperature
If a coating layer of rare-earth phosphate is applied to improve heat resistance, then heat resistance is improved, but thermal residual stress is applied due to difference in thermal expansion coefficient, reducing single fiber strength
Solution Approach 1:
The patent optimizes the thermal expansion parameters by selecting rare-earth elements (ytterbium or lutetum) whose atomic and thermal properties are closer to the ceramic fiber substrate. This parameter matching reduces the thermal expansion coefficient mismatch, thereby minimizing thermal residual stress generation during heating and cooling cycles while maintaining heat resistance.
3Temperature
If heat resistance treatment is applied to improve high temperature performance, then heat resistance is improved, but single fiber strength decreases
Solution Approach 1:
The patent applies a pre-formed coating layer containing ytterbium or lutetum before the fiber undergoes heat resistance treatment. This pre-cushioning coating acts as a protective barrier that mitigates the strength-reducing effects of subsequent heat treatment, allowing the fiber to maintain higher strength levels after exposure to high temperatures compared to untreated fibers.
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 incorporation of ytterbium or lutetium on the surface of continuous ceramic fibers significantly inhibits the decrease in single fiber strength after exposure to high temperatures, maintaining strength retention ratios of 65% or more.
Implementation Method 1
it has been found that grain growth of crystal grains constituting a continuous ceramic fiber is inhibited by a surface different composition region containing a surface metal element
Data Source
AI summary
Provided is at least one of a continuous ceramic fiber in which the decrease in single fiber strength after exposure to a high temperature is inhibited, a method for producing the continuous ceramic fiber, a ceramic matrix composite using the continuous ceramic fiber, and a method for producing the ceramic matrix composite.The continuous ceramic fiber includes a region containing at least one of ytterbium and lutetium on a surface of the continuous ceramic fiber.