Failure Analysis of Ni-8YSZ Electrode under Reoxidation Based on the Real Microstructure.

Area of Science:

• Materials Science
• Electrochemistry
• Mechanical Engineering

Background:

• Solid oxide fuel cells (SOFCs) with Ni-8YSZ anodes face operational challenges.
• Thermal mismatch and reoxidation induce micro-defects, degrading structural integrity.
• Understanding stress distribution in real microstructures is crucial for SOFC durability.

Purpose of the Study:

• To reconstruct and analyze the stress distribution in real Ni-8YSZ microstructures.
• To evaluate the failure probability of 8YSZ under varying reoxidation degrees.
• To identify critical microstructural features contributing to SOFC anode failure.

Main Methods:

• Nano-computed tomography for real Ni-8YSZ microstructure reconstruction.
• Finite element method (FEM) for stress analysis under reoxidation and temperature variations.
• Weibull statistical method for failure probability assessment.

Main Results:

• High stress concentrations identified in thin necks and sharp regions of the Ni-8YSZ microstructure.
• Significant failure probability of 8YSZ observed at 5-10% reoxidation extent.
• Statistical quantification of damaged 8YSZ elements provided.

Conclusions:

• Microstructural features significantly influence stress distribution and failure in SOFC anodes.
• Reoxidation extent is a critical factor determining the mechanical integrity of Ni-8YSZ anodes.
• The study provides essential data for improving SOFC design and operational strategies to enhance longevity.