微波分离场重构技术及其调控化学合成的机理研究

Microwave has been widely applied in synthetic reactions. Previous reactions which were conducted in the microwave separated electric (E) and magnetic (H) field centers show radically different results, thus indicate different mechanisms of interaction between materials and microwave E- or H-field. However, these samples processed in the single mode cavities were usually exposed to only one microwave field component (the E-field component or the H-field component). Therefore, for the first time throughout the world, the microwave Separated Field Reconstructed (SFR) technique is proposed in this project, to study the effect of different combinations of microwave E- and H-field strength on the synthetic reactions. The main research contents in this project include: (1) the microwave Separated Field Reconstructed (SFR) technique, which utilizes two orthogonal single mode cavities to achieve reconstructed microwave field with desired, real-time adjustable electrical to magnetic ratio in specific area; (2) novel numerical calculation method to simulate the different heating profiles of the reactants in the synthetic reaction, which is heated in the microwave Separated Field Reconstructed (SFR) fields; (3) the mechanism of how the reaction is controlled by the microwave field with different electrical to magnetic ratio. Since the effect of the microwave E- or H-field component on the synthetic reactions is not well explained theoretically yet, the mechanism research is going to be comprehensively studied by the combination of simulation and experiments of nano-materials synthesis under the microwave Separated Field Reconstructed (SFR) fields radiation. The study provides theoretical guidance to efficiently synthesize high-performance materials with microwave radiation. Therefore, this project presents critical theoretical value and practical significance.

微波在化学合成方面已经得到了广泛应用。研究表明，微波的电场和磁场分量对反应的促进机理不同。但目前这方面研究通常在微波单模腔的电场中心或磁场中心进行，只能研究单一微波场分量对反应的不同促进效果。为此，本项目在大量前期研究的基础上，首次提出了微波分离场重构技术，即实现微波电场强度和磁场强度任意比例的调控，并研究其对化学合成过程的调控机理。具体包括：（1）微波分离场重构技术：结合两个正交的单模腔，在腔体中心实现重构的微波电场和磁场分量，并通过微波源对场分量进行独立调节；（2）在大功率微波辐照下，分离场重构处理的合成反应中，由于场的选择性加热导致的不同反应物间不同温升的新型仿真计算方法；（3）以纳米材料的分离场重构微波合成实验为例，研究可控比例的微波电磁分量对化学合成的调控机理。该项目的研究将实现以更高效率合成出性能更优的材料，同时达到节能减排的目的，具有重要的科学和工程价值。

微波的选择性加热特性使其在材料合成等领域的应用中独树一帜。本项目进一步结合微波电场和微波磁场与材料的不同互作用机理，研究了微波分离场重构技术以及微波的电/磁分量对混合材料体系的加热与调控特性。主要内容和重要成果包括：（1）提出了微波分离场重构技术和频率追踪快速谐振加热技术：利用正交的微波单模腔，可在样品中实现任意比例可控的微波电场和磁场的组合；在微波加热过程中，材料的介电特性等变化导致腔体的馈入效率和腔内场分布变化，通过使微波源的频率追踪腔体的谐振频率，从而维持能量的高效利用和腔内场分量。（2）研究了微纳尺寸颗粒和含金属粉末样品对微波场的吸收特性，揭示了含金属粉末样品的宏观电导率与微波磁场吸收特性的关联性；建立了多尺度多物理场仿真模型以研究微纳尺度混合粉末样品内不同组分的温度梯度。（3）研究了不同混合材料体系在微波分离（重构）场中处理后的宏微观性质，为微波分离重构场的进一步应用奠定了基础。. 项目研究成果发表高水平SCI论文8篇（其中中科院一区top期刊6篇，4篇发表在《IEEE Transactions on Microwave Theory and Techniques》期刊上），中文核心论文1篇。获多项发明专利授权并申请了美国专利。本项目从基础理论、关键技术、仿真方法和实验测量方面对基于微波分离（重构）场的材料处理进行了系统研究，为微波高效、高性能材料处理奠定了基础。基于此项目拓展的技术有望在雾化、柔性电路焊接等领域得到应用，已与相关公司联合开发应用技术和产品。