Liquid Metal-Based Magnetorheological Fluid with a Large Magnetocaloric Effect

Area of Science:

• Materials Science
• Thermodynamics
• Nanotechnology

Background:

• Classical magnetocaloric materials often suffer from brittleness, low thermal conductivity, and poor machinability.
• Developing advanced magnetocaloric materials is crucial for efficient magnetic refrigeration technologies.

Purpose of the Study:

• To develop a novel magnetocaloric suspension, liquid metal-based magnetorheological fluid (LM²RF), overcoming limitations of traditional magnetocaloric materials.
• To investigate the alloying behavior and magnetocaloric performance of LM²RF.

Main Methods:

• Preparation of LM²RF using liquid metal and Mn_0.6Fe_0.4NiGe_0.54Si_0.46 particles.
• Characterization of the fluid's properties, including thermal conductivity, viscosity, and magnetocaloric effect (MCE).
• Analysis of alloying reactions between liquid metal (galinstan) and magnetocaloric particles over time.

Main Results:

• LM²RF exhibits a large MCE around room temperature with reduced magnetic hysteresis loss.
• The liquid metal carrier enhances heat transfer and widens the operating temperature range.
• Alloying between galinstan and particles is slow and forms a passivating MnGa alloy, minimally impacting MCE.
• The transition temperature (T_m) of LM²RF remained stable for 60 days.

Conclusions:

• LM²RF presents a viable alternative to conventional magnetocaloric materials for magnetic refrigeration.
• The fluid demonstrates excellent thermal properties, stability, and a significant magnetocaloric effect.
• This work paves the way for practical applications of magnetocaloric suspensions in refrigeration.