Du Mengwei, Wang Huixing, Ye Xudan, Qian Kun, Wang Jiong
School of Mechanical Engineering, Nanjing University of Science & Technology, Nanjing 210094, China.
Materials (Basel). 2023 Aug 15;16(16):5627. doi: 10.3390/ma16165627.
In order to investigate the influence of sepiolite minerals on the normal force of magnetorheological grease (MRG), a mixed sample (ALCH) on the basis of preparing an aluminum-lithium-based magnetorheological grease (base sample ALC), containing sepiolite was further prepared. The field-dependent normal force of the two samples was tested using a rotational rheometer, considering conditions such as magnetic field, time, strain amplitude, frequency, and temperature, and the results were compared. The results indicate that sepiolite limits the field dependent normal force of the magnetorheological grease under steady state shear, and is unaffected by magnetic field, time, temperature, and shear rate. Sepiolite has minimal impact on the transient response of the magnetorheological grease. Under oscillatory shear, the magnetic field is an important factor influencing the field-dependent normal force response of the sepiolite-magnetorheological grease (ALCH). At low magnetic fields, the field-dependent normal force of the sepiolite-containing sample (ALCH) is greater than that of the base sample (ALC), while this relationship is reversed at high magnetic fields, unaffected by other factors. Under long-term shear conditions, both samples exhibit good shear stability, as well as consistency at different frequencies and strain amplitudes. However, an increase in shear rate reduces the normal force, and temperature also affects the field-dependent normal force. The patterns of variation in steady-state and oscillatory shear modes are not entirely the same, but both exhibit a characteristic decrease with increasing temperature under high magnetic field intensities. Sepiolite can reduce the temperature sensitivity of the normal force of the magnetorheological grease. In conclusion, the introduction of sepiolite is beneficial for the application of magnetorheology in high-precision devices.
为了研究海泡石矿物对磁流变润滑脂（MRG）法向力的影响，在制备铝锂基磁流变润滑脂（基础样品ALC）的基础上，进一步制备了含海泡石的混合样品（ALCH）。使用旋转流变仪测试了两种样品在磁场、时间、应变幅值、频率和温度等条件下的场依赖法向力，并对结果进行了比较。结果表明，海泡石在稳态剪切下限制了磁流变润滑脂的场依赖法向力，且不受磁场、时间、温度和剪切速率的影响。海泡石对磁流变润滑脂的瞬态响应影响最小。在振荡剪切下，磁场是影响海泡石-磁流变润滑脂（ALCH）场依赖法向力响应的重要因素。在低磁场下，含海泡石样品（ALCH）的场依赖法向力大于基础样品（ALC），而在高磁场下这种关系则相反，不受其他因素影响。在长期剪切条件下，两种样品均表现出良好的剪切稳定性，以及在不同频率和应变幅值下的一致性。然而，剪切速率的增加会降低法向力，温度也会影响场依赖法向力。稳态和振荡剪切模式下的变化规律并不完全相同，但在高磁场强度下均表现出随温度升高而特征性降低的趋势。海泡石可降低磁流变润滑脂法向力的温度敏感性。总之，海泡石的引入有利于磁流变学在高精度设备中的应用。
