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自蔓延高温合成(SHS),也称燃烧合成,对难熔化合物、陶瓷材料和复合材料等的制备具有工艺简单,节能省时等优点,是目前材料工程中极有应用前景并已得到各国广泛重视的新技术。 作者自行设计安装了SHS-自动延时-准等静压系统,使合成与致密化一次完成,提高了工艺质量。对SHS过程进行了热力学和动力学分析,并提出用能量释放速率E_t作为描述SHS过程的特征参量,计算了Ti-C-Ni、Ti-C-Ni-Mo、(TiO_2-Al-C)-(Ti-C-Ni)系的反应热、绝热燃烧温度、质量燃烧速率、能量释放速率及燃烧波速对压坯成分、密度等的依赖关系,计算结果与实验数据吻合良好。建立了SHS-致密化过程的温度-时间-状态图及SHS-致密化判据,确定了最佳致密化工艺参数。采用几种SHS方法制备了致密的TiC-Ni-Mo合金和TiC-Al_2O_3陶瓷,研究了制备方法、压坯成分和工艺参数等对产品的组织结构与力学性能的影响,以及组织与性能之间的关系,探讨了材料的致密化机制。
Self-propagating high temperature synthesis (SHS), also known as combustion synthesis, has the advantages of simple process, energy saving and time saving for the preparation of refractory compounds, ceramic materials and composite materials and is a promising application in materials engineering and has been widely used in various countries Emphasis on new technologies. The authors designed and installed SHS-automatic delay-quasi-isostatic pressing system to complete the synthesis and densification at one time and improve the quality of the process. The SHS process was analyzed by thermodynamics and kinetics and the energy release rate E_t was proposed as the characteristic parameter to describe the SHS process. The Ti-C-Ni, Ti-C-Ni-Mo and (TiO_2-Al- (Ti-C-Ni) -based reaction heat, adiabatic combustion temperature, mass burning rate, energy release rate and combustion wave velocity on the composition and density of compacts. The calculated results are in good agreement with the experimental data. The temperature-time-state diagram and SHS-densification criterion of SHS-densification process were established, and the optimal densification process parameters were determined. The compact TiC-Ni-Mo alloy and TiC-Al_2O_3 ceramic were prepared by several SHS methods. The effects of preparation method, compaction composition and process parameters on the microstructure and mechanical properties of the product were studied. The relationship between the mechanism of material densification.