随着高超声速飞行器速度的提升，高温隔热材料的使用温度将达到1500oC甚至2000oC。然而，基于氧化物的高温隔热材料在高温下将发生烧结，致其热导率急剧升高，亟需设计耐温性好的超高温隔热材料。硼化物陶瓷具有高温稳定性好、扩散系数低、难烧结等优点，但过高的热导率限制了它们作为超高温结构材料的应用。为了实现具有优异超高温热稳定性硼化物作为超高温隔热材料使用的目的，本项目创新性地提出应用硼化物内弱化学键产生的低频光学声子干扰声学声子的思想，实现同时具有高热稳定性及低热导率硼化物隔热材料的设计。拟选择具有高熔点、明显化学键各向异性的六硼化物陶瓷TMB6（TM是金属）为研究对象，通过理论预测的方法，模拟其声子色散关系及本征热导率，建立微观结构与宏观热导率的关系；明确金属原子对六硼化物骨架结构结合强弱以及本征热导率的影响规律，设计和优化六硼化物耐温性和热导率，通过实验验证其作为超高温隔热材料的适用性。

With the increasing of velocity of hypersonic vehicles, the serving temperature of high temperature insulation materials is higher than 1500 oC. However, the sinterability of oxides-based thermal insulation materials is high at this temperature range and the thermal conductivity increased significantly. Thus, insulation materials with good thermal stability and low thermal conductivity are highly desired. Borides are characterized by high melting point, good thermal stability, low diffusion coefficient, and low sinterability. However, high thermal conductivity has impeded the possibility for them as ultrahigh temperature thermal insulation materials. To design novel ultrahigh temperature thermal insulation borides with good thermal stability and low thermal conductivity, in this project, weak bonds in borides are used as phonon scattering structure to low the thermal conductivity of borides by lowering the thermal transport efficiency of acoustic phonons. TMB6 is chosen for their anisotropic bonding character. The crystal structure, electronic structure, phonon dispersion relationship and thermal conductivity of metal hexaborides are theoretically investigated to establish the structure-property relationship. The effect of metal atoms on the chemical bonding and intrinsic heat transport property is also clarified to accomplish the rules for design and tailoring of ablation resistance and thermal conductivity of thermal protection/insulation materials. Then, the selected candidate materials are prepared and tested to show their suitability as thermal insulation materials for ultra-high temperature applications.