Capacitance Probe for CMC Porosity and Phase Composition
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Solution Overview
Problem
Ceramic matrix composites (CMCs) often exhibit uneven distribution of ceramic fibers and matrix, leading to spatial differences in composition and unwanted porosity, which can affect their mechanical, physical, and chemical properties, making it challenging to determine compositional properties like porosity and phase composition effectively.
Innovation Solution
A method using a capacitance probe and controller to subject materials to electric signals at specific frequencies, determining capacitance and porosity based on dielectric constants, allowing for non-destructive assessment of compositional properties such as porosity, phase composition, and material thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional destructive testing methods are used to determine compositional properties, then measurement accuracy is improved, but manufacturing cost and time increase
Solution Approach 1:
The patent replaces destructive mechanical testing methods with non-destructive electrical measurement methods. A capacitance probe applies an electric signal to the CMC material and measures capacitance, which correlates to compositional properties such as porosity and fiber volume fraction. This substitution eliminates the need to destroy test specimens while maintaining measurement accuracy, thereby improving manufacturing productivity and enabling in-process quality control.
2Loss of information
If conventional measurement methods are used, then detailed compositional analysis is achieved, but measurement cost and complexity increase
Solution Approach 1:
The patent replaces complex conventional measurement systems with a simple capacitance-based measurement system. The system uses a capacitance probe connected to a signal generator and meter to measure capacitance, which provides information about compositional properties through dielectric constant variations. This substitution maintains detailed compositional analysis capability while significantly reducing device complexity and measurement cost.
Solution Approach 2:
The patent utilizes changes in dielectric constant as a function of frequency to differentiate between various constituent phases in the CMC material. By measuring capacitance at different frequencies, the system can determine phase composition and porosity based on the frequency-dependent dielectric response of different materials, providing detailed compositional information through a simple parameter change approach.
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
Enables faster and less expensive non-destructive methods for determining compositional properties of materials, providing detailed spatial maps of properties like porosity and phase composition, improving the characterization and quality control of CMCs.
Implementation Method 1
The first constituent phase and the second constituent phase have substantially different dielectric constants at the frequency
Data Source
AI summary
A system may include a controller configured to cause a capacitance probe to subject a material to a first electric signal having a first frequency and determine a first capacitance of the material at the first frequency. The controller is configured to cause the capacitance probe to subject the material to a second electric signal at a second frequency and determine a second capacitance of the material at the second frequency. The material includes at least a first constituent phase and a second constituent phase. The first constituent phase and the second constituent phase have substantially similar dielectric constants at the first frequency and substantially different dielectric constants at the second frequency. The controller is further configured to determine a porosity of the material based on the first capacitance and determine a relative phase composition of the first constituent phase and the second constituent phase based on the second capacitance.