Environmental Barrier Coating Temperature Monitoring
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Solution Overview
Problem
Monitoring the temperature and erosion of environmental barrier coatings (EBCs) in high-temperature gas turbine engines is challenging due to the difficulty of measuring remote, non-contact, or moving parts, especially in corrosive water-containing environments where ceramic matrix composite materials degrade.
Innovation Solution
A method using phosphor thermometry, where a temperature indicator material embedded in the EBC layer fluoresces in response to an excitation beam, allowing for the measurement of surface temperature and erosion based on the intensity and wavelength of emitted radiation, enabling real-time monitoring without adding extra materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher operating temperatures are used to increase gas turbine engine efficiency, then engine efficiency is improved, but the high temperature durability of CMC components deteriorates
Solution Approach 1:
An environmental barrier coating (EBC) system is introduced as an intermediary layer between the CMC substrate and the high-temperature corrosive environment. The EBC includes a bond coat layer and a silica-rich outer layer that acts as a protective barrier, preventing direct exposure of the CMC to water vapor and corrosive gases, thereby maintaining component durability at higher operating temperatures
Solution Approach 2:
The solution uses a composite structure consisting of CMC substrate combined with EBC coating system. The CMC provides structural strength and weight reduction, while the EBC provides environmental protection. This composite approach allows the engine to operate at higher temperatures by combining materials with complementary properties
2Reliability
If protective EBC coating is applied to improve high temperature durability, then component reliability is improved, but the complexity of monitoring EBC health deteriorates
Solution Approach 1:
Temperature indicator materials with phosphorescent properties are incorporated into the EBC structure. These materials exhibit temperature-dependent phosphorescence characteristics, allowing non-contact optical measurement of surface temperature and providing visual/optical signals of EBC health status, thereby simplifying the monitoring approach
Solution Approach 2:
The EBC structure itself serves dual purposes: providing environmental protection and enabling self-diagnosis through integrated temperature indicator materials. The indicator materials are embedded within the coating layers, allowing the coating to monitor its own condition without requiring separate external sensing systems
3Difficulty of detecting and measuring
If non-contact temperature measurement is implemented to monitor moving parts, then measurement capability is improved, but measurement precision in remote locations deteriorates
Solution Approach 1:
Temperature indicator materials serve as an intermediary that converts temperature information into optical signals (phosphorescence). These materials are placed in direct contact with the surface being measured, ensuring accurate local temperature sensing, while the emitted optical signals can be detected remotely using non-contact optical measurement techniques
Solution Approach 2:
The temperature indicator materials exhibit changes in phosphorescence parameters (intensity, decay time, wavelength) as a function of temperature. By measuring these optical parameter changes remotely, precise temperature information is obtained without direct contact, resolving the contradiction between remote measurement capability and precision
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 provides accurate, real-time monitoring of EBC health and temperature, facilitating online prognosis and quality control, and enabling timely repair, while maintaining the existing EBC composition and structure.
Implementation Method 1
A method using phosphor thermometry, where a temperature indicator material embedded in the EBC layer fluoresces in response to an excitation beam
Implementation Method 2
measuring a fluorescent radiation emitted by the bond coat layer and a second fluorescent radiation emitted by the outer layer
Data Source
AI summary
A method of monitoring a surface temperature of an environmental barrier coating (EBC) of a hot gas component includes directing an excitation beam having a first wavelength at a layer of a temperature indicator formed on the hot gas component. The method also includes measuring a fluorescent radiation emitted by the temperature indicator. The fluorescent radiation has a second wavelength and an intensity. In addition, the method includes determining a surface temperature of the EBC based on the intensity of the second wavelength of the fluorescent radiation.