Mohd Nasir Nur Alyaa, Nazmi Nurhazimah, Mohamad Norzilawati, Ubaidillah Ubaidillah, Nordin Nur Azmah, Mazlan Saiful Amri, Abdul Aziz Siti Aishah, Shabdin Muhammad Kashfi, Yunus Nurul Azhani
Engineering Materials and Structures (eMast) iKohza, Malaysia-Japan International Institute of Technology (MJIIT), Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, Kuala Lumpur 54100, Malaysia.
Faculty of Engineering, Universiti Malaysia Sabah, Jalan UMS, Kota Kinabalu 88400, Malaysia.
Materials (Basel). 2021 Sep 6;14(17):5091. doi: 10.3390/ma14175091.
The use of highly viscous grease as a medium in magnetorheological grease (MRG) provides the benefit of avoiding sedimentation from occurring. However, it limits the expansion of yield stress in the on-state condition, thus reducing the application performance during operation. Therefore, in this study, the improvement in the rheological properties of MRG was investigated through the introduction of graphite as an additive. MRG with 10 wt % graphite (GMRG) was fabricated, and its properties were compared to a reference MRG sample. The microstructure of GMRG was characterized using an environmental scanning electron microscope (ESEM). The rheological properties of both samples, including apparent viscosity, yield stress, and viscoelasticity, were examined using a shear rheometer in rotational and oscillatory modes. The results demonstrated a slight increase in the apparent viscosity in GMRG and a significant improvement in yield stress by 38.8% at 3 A with growth about 32.7% higher compared to MRG from 0 to 3 A. An expansion of the linear viscoelastic region (LVE) from 0.01% to 0.1% was observed for the GMRG, credited to the domination of the elastic properties on the sample. These obtained results were confirmed based on ESEM, which described the contribution of graphite to constructing a more stable chain structure in the GMRG. In conclusion, the findings highlight the influence of the addition of graphite on improving the rheological properties of MRG. Hence, the addition of graphite in MRG shows the potential to be applied in many applications in the near future.
在磁流变润滑脂（MRG）中使用高粘性润滑脂作为介质，具有避免沉降发生的优点。然而，这限制了开启状态下屈服应力的扩展，从而降低了运行期间的应用性能。因此，在本研究中，通过引入石墨作为添加剂来研究MRG流变性能的改善情况。制备了含有10 wt%石墨的MRG（GMRG），并将其性能与参考MRG样品进行比较。使用环境扫描电子显微镜（ESEM）对GMRG的微观结构进行了表征。使用旋转和振荡模式的剪切流变仪对两个样品的流变性能进行了检测，包括表观粘度、屈服应力和粘弹性。结果表明，GMRG的表观粘度略有增加，在3 A时屈服应力显著提高了38.8%，与MRG相比，从0到3 A的增长高出约32.7%。观察到GMRG的线性粘弹性区域（LVE）从0.01%扩展到0.1%，这归因于弹性性能对样品的主导作用。基于ESEM证实了这些结果，ESEM描述了石墨对在GMRG中构建更稳定链结构的贡献。总之，这些发现突出了添加石墨对改善MRG流变性能的影响。因此，在MRG中添加石墨在不久的将来显示出在许多应用中应用的潜力。
