ENVIRONMENTAL DEGRADATION OF HARD AND SOFT MAGNETIC MATERIALS IN GASEOUS AND SUPERCRITICAL CO2 ENVIRONMENTS

Conference · Fri Jun 20 04:00:00 EDT 2025

OSTI ID:2570506

Bocher, Florent ^[1]; Rimpel, Aaron ^[1]; Zhang, Wanming ^[2]; Lipham, Robert ^[1]; Shin, Dongil ^[2]; Changizi, Amin ^[2]

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1. Southwest Research Institute, San Antonio, TX (United States)
2. GE Vernova Operations, LLC, Niskayuna, NY (United States)

It may be beneficial to use hermetic designs for supercritical CO2 (sCO2) cycles machinery as they would eliminate CO2 leakage through shaft end seals. This would reduce CO2 emissions and operating costs for makeup of lost process fluid. Those designs may replace traditional oil-lubricated bearings with actively controlled magnetic bearings operating at high temperatures in the process fluid environment (to reduce the need for active cooling). This paper investigates the material degradation of various types of magnets in CO2. Included are several permanent and soft magnetic materials (Alnico 9C, Alnico 5-7C, and 18-T550 grade SmCo, and Hiperco 50) with or without coatings (nickel plating or C5 coating). The materials were exposed to: (1) flowing gaseous CO2 at 1,022 °F (550 °C) and atmospheric pressure in a furnace and (2) sCO2 at 842 °F (450 °C) and 1,500 psi (103 bar) in an autoclave. The preliminary mass change measured after total exposures of 1,000 hours and 2,000 hours are included.

• Research Organization: Golden Field Office, Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• DOE Contract Number: EE0009823
• OSTI ID: 2570506
• Report Number(s): GT2025-153424
• Country of Publication: United States
• Language: English

Related Subjects

supercritical CO2
magnetic material