高铁含量铁基非晶及纳米晶粉体的电磁屏蔽性能调控

Soft magnetic amorphous and nanocrystalline alloys are ideal electromagnetic shielding materials due to their high permeability, low coercivity, and proper permittivity. At present, there are few work related to developing new amorphous/ nanocrystalline alloys for electromagnetic shielding from the viewpoint of composition design. The comprehensive research about the effects of the microstructure and morphology of the powders on the electromagnetic shielding properties is also absent. In this proposal, we plan to first study the effects of minor alloying transition metals (Cr or Mo), and a small amount of substitution of similar ferromagnetic elements (Co or Ni) on the amorphous-forming ability, microstructure evolution during crystallization, and soft magnetic properties of Fe-(Si, B, C)-Cu alloys with high Fe content and develop the amorphous alloy compositions suitable for electromagnetic shielding. Subsequently, we prepare amorphous and nanocrystalline powders by combining the melt-spun, gas atomization, ball-milling methods as well as heating treatment to find out the effects of milling and annealing processes on the microstructure and morphology of the powders. We evaluate the electromagnetic shielding properties of the powders, establish the correlation between the composition, microstructure, morphology and the electromagnetic shielding properties to clarify the related mechanism, and achieve the control of the electromagnetic shielding properties of the powders. Finally, we develop new Fe-based amorphous and nanocrystalline powders with excellent and controllable electromagnetic shielding properties and low cost. The proposed study would provide theoretical guidelines and technical supports for the practical applications of the amorphous and nanocrystalline electromagnetic shielding coating materials.

非晶及纳米晶软磁合金具有高磁导率、低矫顽力和合适的介电常数，是理想的电磁屏蔽材料。当前相关研究鲜有从成分设计角度发展适用于电磁屏蔽的新成分，对粉体微结构和形貌影响电磁屏蔽性能的规律也缺乏系统研究。本项目以高Fe含量的Fe-(B, Si, C)-Cu合金为对象，研究微量过渡金属（Cr，Mo）和少量相似强磁性元素（Co，Ni，Mn）的添加对基础合金非晶形成能力、微结构演化和软磁性能的影响。在优化成分的基础上，结合液态急冷、气雾化和高能球磨工艺并辅以热处理制备非晶、纳米晶粉体，明确制粉和热处理工艺对粉体微结构演化和形貌的影响，评价粉体的电磁屏蔽性能，建立粉体成分、微结构、形貌与电磁屏蔽性能的关联，澄清粉体微结构和形貌影响电磁屏蔽性能的机制，进而实现对其电磁屏蔽性能的调控。发展电磁屏蔽性能优异可控、成本低的Fe基非晶、纳米晶粉体，为非晶及纳米晶电磁屏蔽涂料的实用化提供理论指导和工艺技术支撑。

随着无线通讯技术和智能终端向高频化和集成化快速发展，电磁干扰和电磁污染日益严重，探索和发展新型适用于GHz频率范围的高性能电磁波屏蔽（吸收）材料具有重要意义。本项目以高Fe量的Fe-(B,Si,C,P)-Cu合金为研究对象，首先调查了相似元素Co/Fe置换和微合金化元素Cu量对合金的非晶形成能力、热稳定性、结晶化行为和软磁性能的影响，优选出适用于高Bs的纳米晶软磁合金的合金成分，建立了纳米晶合金的成分-急冷前驱体微结构-热处理后组织结构-磁性能的关联，结合结晶化行为解析和微结构表征明确了高Cu量合金获得微细纳米晶结构和优异软磁性能的机理，提出了含既存α-Fe纳米晶粒的前驱体合金的纳米晶化模型；进而，设计了高Bs的Fe83.3Si4B8P4Cu0.7、Fe80.7Si4B13Cu2.3和Fe90Si7B3纳米晶合金成分，通过球磨法制备合金粉体，研究了球磨时间对粉体形貌、组织结构、电磁参数及电磁波吸收性能的影响规律，考察了热处理工艺对纳米晶合金粉体的微结构和吸波性能的调控作用，阐明了高Fe量纳米晶合金粉体优异电磁波吸收性能的机制；在此基础上，选取纳米晶合金中最佳成分Fe90Si7B3，分别与石墨和SiC复合制备复合粉体，通过球磨、热处理、合金粉体表面改性等工艺调整复合粉体的组织结构和形貌以实现对其电磁波吸收性能的改进与调控，阐明了复合粉体优异电磁波吸收性能的机制，具有Fe90Si7B3非晶/纳米晶核@非晶C壳的类核壳结构的复合粉体因磁损耗与介电损耗的协同效应而在X和Ku波段具有最佳的电磁波吸收性能。此外，本项目还将研究对象扩展到金属-类金属型高熵非晶/纳米晶软磁合金，研究了FeCoNi(P,C,B,Si)和FeNiCrMo(P,C,B)高熵合金的非晶形成能力和性能，明确了该高熵非晶合金优异热稳定性的机理，并研制出具有优异吸波性能的FeCoNi(Al0.2Si0.6B0.2)高熵纳米晶合金粉体。本项目发展的新型Fe基纳米晶软磁合金粉体、Fe基纳米晶软磁合金/碳复合粉体和高熵纳米晶合金粉体电磁波吸收剂吸波性能优异可控、可高效制备且成本低廉，为后续制备以该粉体为填充剂的电磁屏蔽复合涂料提供了理论基础和工艺技术支撑。