Epoxy-bonded La–Fe–Co–Si magnetocaloric plates

Abstract

We report the processing, analysis and testing of magnetocaloric composite materials consisting of La-Fe-Co-Si particles of various size fractions and a polymer matrix. All of the composites have working temperatures close to room temperature. The composites were pressed into thin plates, a geometry favorable for testing the composites in an active magnetic regenerator (AMR). In order to investigate the influence of particle size and binder type (epoxy), eight different epoxy-bonded La-Fe-Co-Si plates were made and analyzed. We found that the higher filling factor that can be achieved by using a mixture of several particle size fractions has beneficial influence on the thermal conductivity. Tests in the AMR revealed that a maximum temperature span of approximately T = 10 K under magnetic field change of 0H = 1.15 T can be obtained at no cooling load conditions. The stability of the measured T values and the mechanical integrity of sample after cyclic application of a magnetic field have been monitored for 90.000 cycles and showed no significant changes. We therefore conclude that epoxy-bonded La-Fe-Co-Si magnetocaloric composites have good magnetocaloric properties at low material-processing costs and hence represent a competetive way to produce magnetocaloric materials to be used in AMR.

On the preparation of La(Fe,Mn,Si)13H polymer-composites with optimized magnetocaloric properties

“…Conversely, the epoxy dilutes the MCE material and the properties of the composite can be significantly different from 65 those reported in literature for pure La(Fe,Mn,Si) 13 H x powder [10,28].…”

“…In order to use the magnetocaloric material in a magnetic refrigerator it should on the one hand be machined into a heat exchanger -a porous structure, designed to provide the largest possible 10 contact surface to the heat transfer liquid. On the other hand the density of the heat exchanger needs to be as high as possible for an efficient use of the magnetic field source.…”

“…As a result, a material with a high magnetocaloric effect in bulk form shows only a modest MCE after it has been shaped into a heat exchanger with sub-millimeter channels [9,10].…”

Structure and magnetocaloric effect of La0.7Ce0.3(Fe0.92Co0.08)11.4Si1.6 bulk alloy prepared by powder metallurgy

“…In the fourth method it was reported that the nearly single NaZn 13 -type phase could be obtained when LaFe 10.8 Co 0.7 Si l.5 C 0.2 powders were sintered at 1100℃ for 4h with 25 LaFe 0.9 Co 0.27 Si 1.17 as a sintering aid, and very few La-rich impurity phase was present [20]. Recently, epoxy-bonded bulk/plate La(Fe,Si) 13 -based compounds were presented by Zhang [21] and Pulko [22], the results show that the epoxy-bonded composite is a promising solution for the manufacturing of more efficient active magnetic regeneration (AMR) with better mechanical properties compared to sintered AMR. However, the magnetocaloric and thermal performances of the epoxy-bonded plates are substantially lower compared to the sintered plates.…”

Active Magnetic Regeneration

“…In Pulko et al [144] epoxy-bonded magnetocaloric plates and then the AMR were evaluated with the goal of fabricating an AMR with thinner plates and a smaller spacing compared to the state-of-the-art sintered AMR (produced by TDR method). As magnetocaloric material LaFe 13−x−y Co x Si y powder (130 μm) was used.…”