Finding Degradation Trigger Sites of Structural Materials for Airplanes Using X-Ray Microscopy

Area of Science:

• Materials Science
• Aerospace Engineering
• Analytical Chemistry

Background:

• Carbon fiber-reinforced plastics (CFRP) and environmental barrier coatings (EBC) are critical aerospace materials.
• Their macroscopic properties can degrade due to localized cracks or chemical changes, termed "trigger sites."
• Identifying these trigger sites is crucial for ensuring material integrity and safety.

Purpose of the Study:

• To develop and apply advanced X-ray techniques for identifying degradation trigger sites in CFRP and EBC.
• To visualize microstructural and chemical state changes at high resolution.
• To investigate material behavior under high-temperature conditions.

Main Methods:

• X-ray microscopy (XM) for non-destructive 2D/3D imaging of microstructures and chemical states.
• High-resolution 3D chemical-state mapping of ytterbium (Yb) in EBC (<50 nm resolution).
• In-situ X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) up to 1773 K.
• Dynamic XAS with nanosecond time-resolution to study local structural dynamics.

Main Results:

• Crack initiation in CFRP was observed non-destructively across multiple scales (nm-mm).
• High-resolution 3D chemical-state mapping of Yb in EBC was successfully achieved.
• Simultaneous in-situ XAS and XRD provided complementary high-temperature data.
• Dynamic XAS revealed rapid local structural changes in metals.

Conclusions:

• The combined X-ray techniques effectively identify degradation trigger sites in CFRP and EBC.
• High-resolution imaging and in-situ analysis provide critical insights into material degradation mechanisms.
• These methods enhance the understanding and prediction of material failure in aerospace components.