磁性金属吸波剂的高温氧化问题及其对策研究进展

Progresses and Strategies Against High Temperature Oxidation of Magnetic Metallic Absorbents

中文关键词: 高温吸波涂层  磁性吸波剂  表面包覆  致密氧化膜  抑制扩散

英文关键词: high temperature microwave absorbing coating  magnetic absorbent  surface coating  dense oxide film  inhibiting diffusion

中文摘要:

      目的 针对磁性金属吸波剂由组成元素化学性质活泼导致的高温氧化和电磁性能恶化问题展开现状调研和讨论，解析磁性金属吸波剂高温氧化的机理，并提出相应的解决策略。方法 从氧气在金属吸波剂中的吸附、反应和传质过程出发，讨论高温氧化对吸波剂电磁性能的影响规律，系统总结并评述表面包覆隔绝氧气、生成致密金属氧化膜和抑制氧原子扩散3种策略对吸波剂抗高温氧化的作用机制。结论 表面包覆策略通过引入有机高分子、无机化合物或磁性金属等包覆物质，以隔绝氧气，从而抑制磁性金属吸波剂的高温氧化。其中，无机化合物包覆体系最具潜力，但尚未达到理想的超薄致密状态。生成致密氧化膜策略通过溶质元素的选择性氧化，形成保护膜，能够有效抑制氧化进程，但引入较高含量的非铁磁性溶质元素容易降低磁导率、恶化吸波性能。抑制氧原子扩散策略通过形成晶界氧化物来有效减缓氧化，目前其实现手段有限且不够成熟。在耐温磁性吸波剂的研制中应综合考虑使用温度、基体材料、目标吸波频段和期望吸波性能等，采用合适的抗氧化策略。

英文摘要:

      The work aims to investigate and discuss the high temperature oxidation of chemically active elements in magnetic metallic microwave absorbents (MMMA) and the resulting deterioration of electromagnetic properties in MMMA, to analyze the high temperature oxidation mechanism of MMMA and put forward corresponding strategies. Based on the process of oxygen adsorption, reaction and mass transfer in MMMA, the effect of high temperature oxidation on the electromagnetic properties was discussed. Three main strategies against high temperature oxidation in MMMA were proposed and reviewed, i.e., oxygen isolation from MMMA, formation of dense oxides on surface and suppression of oxygen diffusion. The strategy of oxygen isolation from MMMA has effectiveness in anti-oxidation by surface coating of organic polymers, inorganic compounds or magnetic metals. Among those coating materials, inorganic compounds are most promising, whereas the ultrathin dense coating of inorganic compounds is still challenge. The strategy for formation of dense oxides on surface have shown its potential in anti-oxidation for MMMA with selective oxidation of solute elements, forming protective film to effectively inhibit the oxidation process, but the introduction of high content of non-ferromagnetic solute elements is easy to reduce the magnetic permeability and deteriorate the microwave absorbing performance. The strategy for suppression of oxygen diffusion has been achieved by forming oxides in grain boundaries of MMMA to reduce diffusion paths of metal ions, active oxygen atoms and free electrons, while efficient methods to realize oxygen diffusion suppression are still absent. In view of the research of MMMA resistant to high temperature, it is necessary to consider the using temperature, type of matrix material, working frequency band and expecting absorption performance, thereby selecting appropriate anti-oxidant strategy.