ZrB2-SiC陶瓷与钎料合金界面TiB晶须原位生长行为及应力调控机制研究

In order to overcome the low strength and high stress of the ceramic/brazing alloy interface, in this project, TiB whisker with 1D alone or dual distribution of 1D and 3D was in situ synthesized at the interface between ZrB2-SiC ceramic and brazing alloy based the surface characteristics of ZrB2-SiC ceramic, which can effectively improve mechanical performances and adjust the stress distribution. The dynamic growth model of TiB whisker was founded by the research of the characteristics of distribution and growth mechanism of TiB whisker. The effects of in situ synthesized TiB whisker on the residual stress of the interface and joint were clarified through FEM simulation, mesoscopic mechanical analysis and macro-mechanical evaluation. At the same time, the process was also optimized and the best performance was also obtained after the comprehensive performances and strengthening mechanism of the joint between ZrB2-SiC ceramic and metal were studied. All of the above researches will explore new ideas and lay the theoretical foundation for the joining of ceramic and metal.

本项目针对陶瓷与钎料合金界面强度低，应力集中的难题，根据ZrB2-SiC陶瓷自身特点，通过在ZrB2-SiC陶瓷与钎料合金界面原位生长1D或与3D复合分布的TiB陶瓷晶须提高连接界面的力学性能并调节应力分布。在对ZrB2-SiC陶瓷与钎料合金界面TiB晶须分布特征、生长机理研究的基础上，建立原位TiB晶须在ZrB2-SiC陶瓷与钎料合金界面成长的动力学数学模型；通过有限元数值模拟、细观力学分析并结合宏观应力的评价阐明原位自生TiB晶须对界面及接头残余应力的调节机制。与此同时通过对ZrB2-SiC陶瓷与金属连接接头的综合力学性能及强化机制进行研究，优化工艺参数，获得最佳的接头性能，为ZrB2-SiC陶瓷与金属材料连接开拓新思路和奠定理论基础。

ZrB2-SiC复合陶瓷（ZS）具有高熔点、低密度、良好的导电性/导热性以及优异的抗烧蚀能力，可作为高速飞行器端帽、翼尖等严酷环境中服役的热结构材料。研究ZS陶瓷自身及其与金属的连接将有助于制备大型或复杂构件，对于拓宽ZS陶瓷的应用范围具有重要意义。本项目针对陶瓷与钎料合金界面强度低、应力集中的难题，从ZrB2-SiC复合陶瓷的结构特点出发，提出TiB晶须原位增强连接法，即利用ZrB2分解释放出的B原子作为B源，在接头中制备TiB，通过控制工艺条件实现TiB的合理分布，获得了原位TiB晶须增强的ZrB2-SiC复合陶瓷自身及其与不同金属材料的连接接头。采用不同体系的合金钎料及中间层材料，通过对不同接头的界面组织演化机理研究，揭示了TiB晶须在液相与固相中的生长机制、生长动力学以及不同接头的形成机制，并结合热力学计算，阐明了多种因素对于TiB晶须生长的影响作用及规律，从中选择出了最佳工艺参数；利用细观力学的相关理论，采用有限元方法模拟了TiB晶须周围的应力分布特点，阐述了TiB晶须对接头增强区热膨胀系数和弹性模量的调节作用，从而进一步说明了晶须对接头微观组织及力学性能的影响规律；开展了对不用接头的力学性能及相应断口的观测和分析，建立了TiB晶须生成尺寸、密度、分布与接头强度的关系，揭示了TiB晶须对ZrB2-SiC复合陶瓷连接接头的增强、增韧机制。为ZrB2-SiC陶瓷与金属材料连接开拓新思路和奠定理论基础。