We present results concerning the fabrication of a new magnetorheological fluid with FeCo magnetic nanoparticles (NPs) as magnetic fillers. These NPs have been fabricated by using the chemical reduction technique and show a pure crystalline phase with size ranging among 30–50 nm and high magnetization, 212 ± 2 A m² kg⁻¹. They agglomerate due to the strong magnetic dipolar interaction among them. These FeCo nanoparticles were used to synthesize a magnetorheological fluid by using oleic acid as surfactant, mineral oil as carrier liquid and Aerosil 300 as additive to control the viscosity of the fluid. The synthesized fluid showed a strong magnetorheological response with increasing shear stress values as the magnetic field intensity increases. Thus, we have measured a superior performance up to 616.7 kA m⁻¹, with a yield stress value of 2729 Pa, and good reversibility after demagnetization process. This value competes with the best ones reported in the most recent literature. We have compared the obtained results with our previous reported ones by using high magnetization Fe NPs fabricated by the electrical explosion of wire method (Fe-EEW).

中文翻译：

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高磁化FeCo纳米颗粒用于磁流变液，具有增强的响应

我们目前的结果有关制造新的磁流变流体与FeCo磁性纳米粒子（NPs）作为磁性填料。这些NP是使用化学还原技术制造的，显示出大小在30–50 nm之间且具有高磁化强度的纯晶相，212±2 A m ² kg ^-1。由于它们之间的强磁偶极相互作用，它们会聚结。通过使用油酸作为表面活性剂，矿物油作为载液以及Aerosil 300作为添加剂来控制流体的粘度，将这些FeCo纳米颗粒用于合成磁流变流体。随着磁场强度的增加，合成流体表现出较强的磁流变响应，且剪切应力值增大。因此，我们测量了高达616.7 kA m ^-1的卓越性能，屈服应力值为2729 Pa，去磁后可逆性好。该值与最新文献中报道的最佳值竞争。我们将通过线爆炸法制造的高磁化铁纳米颗粒（Fe-EEW）与获得的结果进行了比较。