低温表面活性剂辅助球磨制备稀土硬磁纳米颗粒和片状材料

Rare earth hard nano-magnetic materials have the potential applications in many fields such as permanent magnetic materials, magnetic recording media, magnetic fluid, etc. It is not easy to prepare the rare earth hard nano magnetic materials. The surfactant assisted ball milling(SABM) is one of few methods to fabricate the rare earth hard nanoparticles and nanoflakes. All previous works about SABM for fabricating the nano magnetic materials is performed at room temperature (RT). In this project, we will explore a new method--surfactant assisted cryomilling. The temperature is the key parameter for fabricating the nano materials. The morphology, microstructure and magnetic properties of nano materials fabricated by surfactant assisted cryomilling will be different from those prepared by previous RT SABM. We will investigated systematically the effect of different surfactants on the size, morphology, strain, microstructure and magnetic properties of Sm-Co, Nd-Fe-B and Sm-Fe-N nanoflakes and nanoparticles prepared by surfactant assisted cryomilling. The relationship between the microstructure and magnetic properties, and the key factor to influence and improve the magnetic properties of rear-earth hard nanoflakes will be addressed. The relationship between the intrinsic magnetic properties and size of nanoparticles will be characterized at the nanoscale.

纳米稀土硬磁材料在永磁材料、磁记录、磁流体、医学等许多领域具有重要的应用前景，稀土硬磁纳米材料较难制备，表面活性剂辅助球磨是制备稀土硬磁纳米颗粒和片状材料少有的几种方法之一。以往所有关于表面活性剂辅助球磨制备稀土硬磁纳米材料都集中在室温。通过本项目资助，我们将进行一种新方法--低温表面活性剂辅助球磨法的探索和研究。温度是影响纳米材料制备的一个重要条件，低温表面活性剂辅助球磨对制备材料的形貌、微观结构和磁性能等方面的影响将不同于以往常用的室温表面活性剂辅助球磨。我们将系统研究低温表面活性剂辅助球磨法不同表面活性剂及球磨参数对Sm-Co、Nd-Fe-B和Sm-Fe-N硬磁纳米颗粒和纳米片尺寸、形貌、应力、微观结构和磁性能的影响规律及特点，微观结构与磁性能的关系，以及影响和提高稀土硬磁纳米片磁性能的关键因素。研究稀土硬磁纳米颗粒内禀磁性能与尺寸的关系，揭示二者在纳米尺度下的变化规律。

稀土硬磁(也称永磁)微纳米材料在永磁、磁性液体、磁记录等方面有重要应用。稀土硬磁纳米材料由于含有稀土，较易氧化，很难制备。表面活性剂辅助球磨是制备稀土硬磁纳米材料重要方法之一。以往所有表面活性剂辅助球磨都在室温进行，通过本项目资助，我们进行了一种新方法━低温表面活性剂辅助球磨的探索和研究。率先系统开展了低温表面活性剂辅助球磨制备稀土永磁微/纳米颗粒材料研究，发现低温表面活性剂辅助球磨相比目前室温球磨相比，具有如下优点：（1）降低颗粒尺寸提高均匀性；（2）提高磁性能；（3）抑制稀土合金氧化及非晶化。（4）表面活性剂易于去除。研究结果对于制备用于电动汽车和风电等的高性能稀土永磁材料，解决其面临的关键问题，具有重要的意义。