钼基合金是有望取代镍基合金成为下一代高温合金的候选材料之一，然而钼基合金600℃以上的高温氧化问题限制了其应用。本申请将采用等离子弧喷焊技术，在钼基体上制备以Mo5Si3和Mo5SiB2（T2）为弥散分布相、Mo3Si/T2共晶组织为连续基体的Mo-Si-B合金涂层，基于前期研究发现的T2相对涂层高温抗氧化性能影响的双尺度效应，拟设计并制备具有不同双尺度T2相分布权重的Mo-Si-B涂层，通过对其微观组织的定量表征以及不同温度下对涂层界面结合强度、抗热震性能、抗氧化性能的测试，系统研究涂层微观组织演变对其性能的影响规律，建立涂层组织与其性能之间的内在联系，揭示涂层的界面失效机理，阐明双尺度T2相对涂层抗氧化性能单独及耦合影响的微观机理。研究结果将明确涂层抗氧化性能最佳的微观组织特征参数，为高性能Mo-Si-B合金涂层微观组织的优化设计与抗氧化性能的调控提供实验数据和理论参考。

Mo-based alloys may be a prospective candidate as one of the most promising superalloys to replace the Ni-based superalloys. However, the poor oxidation resistance of Mo-based alloys restricts their applications at high temperatures (above 600℃) in air. This project will fabricate Mo-Si-B alloy coatings with Mo5Si3 and Mo5SiB2 (T2) as dispersion phases and Mo3Si/T2 eutectics as continuous matrix onto Mo substrate by plasma transferred arc process. Based on the bi-scale effect of T2 phase on the high-temperature oxidation resistance of the coating found in previous investigation, Mo-Si-B alloy coatings with different contents of bi-scale T2 phase distribution will be designed and prepared. The coatings’ microstructure will be characterized quantificationally, and their interface bonding strength, thermal shock resistance, and oxidation resistance related to temperatures will be evaluated to investigate the influence law and establish relationship between the microstructure and the coatings’ properties. Subsequently, the failure mechanism of the interface bonding will be revealed and the micromechanism of the effect of bi-scale T2 distribution on oxidation resistance will be clarified. Finally, optimization of the microstructure will be obtained, which will provide experimental data and theories for the microstructure design and oxidation resistance control of Mo-Si-B alloy coating.