ZrB2基超高温陶瓷以其优异的高温综合性能成为高超飞行器领域重要的先进结构材料。采用微结构调控，优化相界面结构，获得全致密、超细化的纳米织构复相陶瓷是改善和提高性能的重要新途径。针对传统烧结方法制备ZrB2基陶瓷难致密化、晶粒长大、界面存在玻璃相及韧性差等问题，本项目将熔体液固相变与ZrB2基复相陶瓷成分设计相结合，拟采用激光悬浮区熔高梯度定向凝固技术，通过精确控制单向热流和凝固过程、引入籽晶及第三组元，原位制备组织超细化、相分布均匀、取向精度高的高强韧ZrB2-SiC纳米织构共晶复合陶瓷，探明凝固工艺、籽晶取向及第三组元对凝固组织、液固界面、生长取向和相界面结构的影响规律，建立超高温硼化物共晶陶瓷熔体取向生长与组织控制方法，构建强各向异性硼化物小平面相共晶生长模型，揭示多元复相纳米织构硼化物共晶陶瓷的强韧化机理和氧化行为，为发展高致密、强韧化超高温陶瓷及其凝固制备技术提供理论和技术基础。

ZrB2-based ultra-high-temperature ceramics are the ones of the most important advanced ultra-high-temperature structural materials in the field of hypersonic aircrafts due to their excellent high-temperature properties. Controlling microstructures and optimizing phase interface structures to obtain highly dense and ultra fine nano-texture composite ceramics are new vital ways to greatly improve the material property. In order to overcome the fatal preparation drawbacks including low densification, coarse particle and interface amorphous phase as well as poor fracture toughness for conventional solid sintered ZrB2-based composite ceramic, this propose is devoted to develop the melt growth method to prepare the highly densed ZrB2-SiC nano-texture ultra-high-temperature eutectic composite ceramic by using the novel laser floating zone remelting method based on the melt solid-liquid phase transformation and ceramic composition design theories. The ultra-fine nanoeutectic structure with uniform distribution and high growth orientation will be prepared and adjusted by accurately controlling the unidirectional thermal flow and solidification process, and introducing seed crystal as well as the third composition additions, accordingly improving the strength and fracture toughness.The effects of solidification processing parameters,seed crystal orientation and third composition additions on the eutectic microstructure, solid-liquid interface and preferred growth orientation as well as the phase interface structure will be systematically investigated, thereby establishing the melt growth and orientation controlling method for the ultra-high temperature boride-based eutectic composite ceramics. The eutectic growth model for the faceted boride phase with strong growth anisotropy is going to be obtained. The strengthening and toughening mechanisms as well as ant-oxidization behaviors for the nano-textured boride-base eutectic composite ceramics are to be revealed. The fundamental investigation of this project is to provide theoretical foundation and technical support for developing superior ultra-high-temperature composite ceramics with high densification, high strength and toughness, and to further enrich and develop eutectic solidification theory.