热压La_(0.8)Ce_(0.2)Fe_(11.45)Mn_(0.25)Si_(1.3)H_(1.8)磁工质的性能研究

Study on the Properties of Hot Pressed La_(0.8)Ce_(0.2)Fe_(11.45)Mn_(0.25)Si_(1.3)H_(1.8) Magnetic Refrigerant

采用工业纯原料,利用中频感应炉制备La0.8Ce0.2Fe11.45Mn0.25Si1.3铸锭,在高纯氩气保护下退火后淬火。铸锭磨成粉末并装入热压炉模具中热压成型,热压温度选取723 K,873 K,1023 K及1173 K,压力30 MPa,保压时间30 min。热压样品切成薄片并饱和渗氢,测试材料结构、微观组织及磁热性能。实验结果表明,块状样品及热压样品均形成NaZn13结构相。与块状样品相比,热压样品的磁热效应均低于块状样品,但随着热压温度的提高,样品的磁热效应逐渐增大。在1.5 T磁场、1173 K温度下,热压样品性能最高,最大磁熵变ΔSM为10.87 J/(kg·K),体积熵变为66.80 kJ/(m^(3)·K),最大绝热温变ΔTad为2.4 K,能够满足室温磁制冷机的应用。

La0.8Ce0.2Fe11.45Mn0.25Si1.3ingot was prepared by medium frequency induction furnace with industrial pure raw materials, then annealed under the protection of high purity argon and quenched. The ingot is grinded into powder and loaded into the mould of hot-pressing furnace. The hot-pressing temperature is 723 K, 873 K, 1023 K and 1173 K, the pressure is 30 MPa and the press time is 30 min. The hot-pressed sample was sliced and saturated with hydrogen. The structure, microstructure and magnetocaloric properties of the material were tested. The experimental results show that both bulk and hot pressed samples form NaZn13phase. Compared with bulk samples, the magnetocaloric effect of hot pressed samples is lower, but the magnetocaloric effect of hot pressed samples increases with the increase of hot pressing temperature. The performance of hot-pressed sample is best pressed at 1173 K, the maximum magnetic entropy changes ΔSMis 10.87 J/(kg·K), the volume entropy is 66.80 mJ/(cm^(3)·K) and the maximum adiabatic temperature ΔTadis 2.4 K under the magnetic field of 1.5 T, which can meet the application of room temperature magnetic refrigerator.