Matran Wail M, Mustapha Mazli, Nor Mohd Faizairi, Mustapha Faizal, Alakbari Fahd Saeed, Al-Shawesh Gamal, Bawahab Mohammed
Department of Mechanical Engineering, Universiti Teknologi PETRONAS, Malaysia.
Department of Aerospace Engineering, Universiti Putra Malaysia, Malaysia.
Heliyon. 2024 Sep 30;10(20):e38766. doi: 10.1016/j.heliyon.2024.e38766. eCollection 2024 Oct 30.
In recent decades, the rising demand for permanent magnetic materials has driven manufacturers to explore substitutes for rare earth elements in response to their fluctuating prices and negative environmental impact. M-type hexaferrites considered as good alternatives and studies have focused on enhancing their magnetic and structural properties through various approaches. In this study, new approach using low heating rate microwave sintering has been applied to investigate the changes on density, microstructure, and magnetic properties of strontium hexaferrite from core to surface. Sintering temperatures of 950 °C, 1000 °C, 1050 °C, and 1100 °C with 10 °C/minute heating rate were applied accordingly. The bulk density, FESEM, XRD and VSM tests were conducted to study materials' properties. The outcomes of the study showed exponential relationship between density and sintering temperature reaching optimum value of 91.4 % at 1050 °C and then declined slightly at observed to analysis confirmed the magnetoplumbite structure 6/ in all samples and high crystallized structure at 1050 °C, with the occurrence of α-Fe2O3 at 1100 °C. Grain growth and crystallization observed to increase at higher sintering temperature with agglomeration while denser and melted boundaries at lower temperatures. Magnetic properties especially remanence magnetization Mr and saturation magnetization Ms fluctuated with sintering temperature achieving optimum values of 28.188 emu/g and 55.622 emu/g at 1000 °C respectively. Coercivity Hc and magnetic energy density BH max recorded optimum values at 1050 °C. The findings emphasize the critical role of microwave sintering in tailoring the properties of strontium hexaferrite for magnetic applications.
近几十年来，对永磁材料需求的不断增长促使制造商探索稀土元素的替代品，以应对其价格波动和负面环境影响。M型六铁氧体被认为是很好的替代品，并且研究集中在通过各种方法提高其磁性能和结构性能。在本研究中，采用低加热速率微波烧结的新方法来研究锶铁氧体从核心到表面的密度、微观结构和磁性能的变化。相应地采用了950℃、1000℃、1050℃和1100℃的烧结温度，加热速率为10℃/分钟。进行了体密度、场发射扫描电子显微镜（FESEM）、X射线衍射（XRD）和振动样品磁强计（VSM）测试来研究材料性能。研究结果表明，密度与烧结温度之间呈指数关系，在1050℃时达到最佳值91.4%，然后略有下降。观察到分析证实所有样品中均为磁铅石结构6/，在1050℃时为高结晶结构，在1100℃时出现α-Fe2O3。观察到在较高烧结温度下晶粒生长和结晶增加并伴有团聚，而在较低温度下边界更致密且有熔化现象。磁性能尤其是剩磁Mr和饱和磁化强度Ms随烧结温度波动，在分别在1000℃时达到最佳值28.188 emu/g和55.622 emu/g。矫顽力Hc和磁能密度BH max在1050℃时记录到最佳值。这些发现强调了微波烧结在定制用于磁性应用的锶铁氧体性能方面的关键作用。
