气雾化Ti基纳米晶合金粉末形成机理及其脱合金化机制

In order to resolve future energy problem, the developments of high efficient solar-energy conversion materials have become hot research topics throughout the world. Due to their advantages of stable properties and without toxic influence to the environment, Ti-based metal oxides exhibit broad application fields as high-performance functional materials. However, the widespread engineering applications of Ti-based metal oxides are severely hindered by the problems of low solar-energy conversion efficiency and difficulty in separation and recovery. To overcome these restrictions, core-shell structured metal oxide composites with improved properties have been synthesized by dealloying strategy using Ti-based nanocrystalline metallic powders as precursors. Moreover, the fabrication of bulk Ti-based alloys using consolidation of nanocrystalline metallic powders offers a new way for the design of novel light-weight structural materials with excellent properties. In this project, the fabrication and dealloying of Ti-based nanocrystalline metallic powders will be performed. Based on suggesting the strategies for obtaining Ti-based nanocrystalline metallic powders by controlled nanocrystallization and in situ one-pot synthesis and modifying of metal oxide composites, the law of precipitation of nanocrystals and dealloying mechanism for the Ti-based metallic powders will be revealed systematically. In addition, the mechanism of solar-energy conversion for the core-shell structured metal oxide composites will be also investigated. These results will help to clarify the relationships among the metallic elements, nanocrystallization, microstructure, dealloying and solar-energy conversion. The expected achievements will provide more basically theoretical details for the exploitation of novel Ti-based nanocrystalline alloys in light-weight structural and energy materials fields and further accelerate their promising applications.

为了解决能源问题，新型高效光能转换材料的开发成为全世界研究人员关注的热点。Ti基金属氧化物粉体材料因稳定性高、无毒害性等优势而备受关注，而光能利用率低、难以分散回收等问题制约了其工程化应用。采用Ti基纳米晶合金粉末为原料，脱合金化合成核壳结构复合金属氧化物粉末，可以提高单一金属氧化物的光能利用率并突破其分散回收应用瓶颈。此外，Ti基纳米晶合金粉末用于固结成形制备块体Ti基合金为新型高性能轻量化结构材料的开发提供了新方法。本项目针对Ti基纳米晶合金粉末制备及脱合金化，提出可控纳米晶化制备合金粉末以及原位合成改性金属氧化物的新思路，揭示Ti基合金粉末纳米晶析出规律与脱合金化机制，阐明核壳结构复合金属氧化物粉末光能转换机理，建立合金元素-纳米晶化-微观组织-脱合金化-光能转换之间的内在联系，为Ti基纳米晶合金在轻质结构材料及新型能源材料领域的应用提供基础科学指导依据。

本项目采用快速凝固方法，制备了亚稳Ti基合金粉末，对合金粉末在快速冷却和再加热过程中的纳米晶化行为进行了系统的研究。结果表明不同的热力学与动力学条件导致了不同的晶体形核、长大速率，在大过冷度下发生晶化，有利于获得纳米级的晶化产物。另外，采用快速凝固方法制备了多种成分的Ti基、Al基合金粉末，并对合金粉末的快速凝固特征进行了研究。以Ti基合金粉末为原料，采用水热反应的方法制备了核壳结构复合金属氧化物粉末材料，揭示了元素添加对合金粉末脱合金化的影响机理。结果表明合金组元间标准电极电势是导致脱合金化过程发生的热力学驱动力，而驱动力差异是多组元合金粉末选择性脱合金化反应的主要原因。基于上述反应原理，以多种成分的合金粉末为原料，采用脱合金化方法制备了多种独特形貌的微纳米结构粉末。对制备的复合金属氧化物粉末进行了光能转换性能测试，样品在波长300-600nm入射光的照射下，均表现出响应电信号，即粉末材料的光吸收/转换范围达到了可见光区，而产物的结晶完整性与对光能的有效吸收利用有利于材料光能转换性能的提高。此外，对所制备的多种新型核壳结构粉末的功能化性能进行了研究，结果表明粉末材料具有优异的吸收电磁波及吸附液态体系中有毒离子的性能。