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Encapsulated Copper-Based Phase-Change Materials for High-Temperature Heat Storage.
Xin Zhou1, Seiji Yamashita2, Mitsuhiro Kubota1
1Graduate School of Engineering, Department of Chemical Systems Engineering, Nagoya University, Nagoya 4648603, Japan.
A novel copper-aluminum capsule encapsulated in alumina was developed for high-temperature heat storage above 1000 °C. This self-sealing capsule exhibits excellent durability and oxidation resistance during long-term air exposure.
Area of Science:
- Materials Science
- Chemical Engineering
- Energy Storage
Background:
- High-temperature heat storage requires materials that can withstand extreme conditions and resist degradation.
- Conventional heat storage capsules often suffer from oxidation and mechanical failure at temperatures exceeding 1000 °C.
- Developing robust and durable capsules is crucial for advancing high-temperature thermal energy applications.
Purpose of the Study:
- To develop a novel copper-based capsule encapsulated by an alumina shell for high-temperature heat storage (>1000 °C).
- To investigate the self-sealing mechanism and long-term durability of the developed capsule under harsh conditions.
- To evaluate the oxidation resistance and mechanical stability of the capsule for practical applications.
Main Methods:
- Fabrication of a copper-aluminum (Cu-Al) capsule within a black alumina shell using a simple heat-treatment process.
- Incorporation of Cu beads and Cu-Al atomized powder within the alumina shell.
- Analysis of the capsule's microstructure, composition, and self-sealing mechanism using X-ray diffraction (XRD) and scanning electron microscopy (SEM).
- Evaluation of the capsule's performance through a 400-hour air exposure test at 1100 °C.
Main Results:
- A high-density, aluminum-rich network formed around Cu beads, significantly reducing copper oxide (CuO) corrosion.
- A two-step reaction (Cu → CuO, CuO + Al2O3 → CuAl2O4) led to in situ sealing of the capsule, preventing oxygen ingress.
- The Cu-(5-10%) Al capsule demonstrated excellent durability, enduring 400 hours at 1100 °C without leakage or cracking.
- The capsule exhibited good oxidation resistance (3.5% weight increase) and mechanical stability after prolonged exposure.
Conclusions:
- A simple and effective method for fabricating durable Cu-Al capsules for high-temperature heat storage (>1000 °C) was established.
- The self-sealing function, driven by a specific reaction pathway, enhances capsule longevity and performance.
- The developed capsule shows significant promise for high-temperature heat storage applications, offering excellent oxidation resistance and mechanical integrity.
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