【摘要】 目前的自蔓延高温合成(self-propagating high-temperature synthesis,SHS)模拟过程都是采用只考虑传热过程的Fourier模型,没有反映流动和扩散等传质过程及其对传热的影响。在压实材料的SHS过程中,因为燃烧、熔化和冷却过程都很快,使得对流和扩散行为来不及充分进行;然而在这种密实体中,毛细流动会很快,成为SHS过程中主要的传质行为。据此,首先推导出毛细流动引起的填充率变化函数,再将填充率与Fourier模型结合,推导出同时包含传质和传热的新模型;用Fourier模型与新模型分别对Ti–C体系的SHS过程进行数值模拟,结果表明:新模型得到的模拟结果有燃烧温度高、燃烧面长、燃烧前沿稳定、蔓延速率低等明显变化;新模型可以同时反映传热和传质行为,更符合实际过程,从而有助于深入理解SHS过程。更多还原

【Abstract】 The Fourier model is widely used to simulate the self-propagating high-temperature synthesis(SHS) process,but this model does not reflect the mass transfer process and its influence on heat transfer.In the process of SHS in a compacted block,burning,melting and cooling occur rapidly in a rather short time.The duration is too short to complete the flow of the convection and diffusion.However,the capillary flow is not restricted during the short duration.Thus,the capillary flow could be the main mass transfer process in SHS.In this paper,the function of fill factor caused by the capillary flow was derivated,a novel model combining with the fill factor and the Fourier model was proposed.The SHS process was simulated with the proposed model and the Fourier model for Ti–C sys-tem,respectively.The results by the proposed model are different in the combustion temperature,combustion stability and combus-tion propagation velocity,compared to the results by the Fourier model.The proposed model of capillary flow can reflect heat and mass transfer behaviors simultaneously,which can give more information to understand the actual SHS process.更多还原