Magnetocaloric Effect Research Of LaFeCoSi Series Material

Magnetic refrigeration is a new-typed refrigeration technology using magnetic material as work-medium. The fundamental principle of magnetic refrigeration is in virtue of the magnetocaloric effect(MCE)of magnetic refrigeration material, i.e. the magnetic refrigeration material expels heat when it is magnetized isothermally, and absorbs heat when it is demagnetized adiabatically. In engineering, refrigerated aim is achieved by transferring and expelling heat in high temperature end, absorbing heat and cumulating in low temperature end. The magnetic refrigeration technology will have a great future in family refrigerator, air condition, food industry and medical industry. In contrast with conventional gas refrigeration technology, magnetic refrigeration is attended widely with high efficiency, economy energy and environment safety. In order to develop the potential applications of the room-temperature magnetic refrigeration technology in the fields of home refrigerator, automobile air condition, food industry, medicine and sanitation, etc, it is a key to look for room-temperature magnetic refrigeration material with giant MCE.In recent research work, the La(Fe Co Si)13 series compounds are prepared by melting method, the samples have good rigidity and great brittleness, so it is difficult to process the alloys into refrigerant.In this paper, we prepared the La(Fe Co Si)13 series compounds with industrial purity raw materials for the purpose of practice using. We melted and carried on heat treatment numbers of La(Fe Co Si)13B samples. We measured adiabatic temperature change and isothermal entropy change, studied the microstructure and phase structure by SEM and XRD later. We prepared particle of the samples in vacuum glove box. Then the particle was ball milling with different times. And we prepared powder with diameters less than 0.15 mm at end. Next the powder was put into module and sintered in SPS system. All the samples were carried on heat treatment under 1070℃.In this paper, the influence of heat treatment time and milling time on the performance of La Fe11.1Co0.8Si1.1B0.25 sample was studied. When milling time is 1h, the ?Tad and ?Sm increase as heat treatment time increasing, and have a largest value as the heat treatment time is 20 h. As the heat treatment time is 1h, the ?Tad and ?Sm increase as ball milling time increasing. Based on these results, we could know that the ?Tad and ?Sm increase as ball milling time increasing under same heat treatment condition. When the ball milling time is 2h, ?Tad=1.8K,?Sm=4.1 J/ kg ?K. It means that the values are related with powder size. It indicate that smaller powder size is good for alloy composition homogenizing and the formation of Na Zn13 main phase.