Yang Junsheng, Fan Yiquan, Tan Hua, Liu Wenkang, Kuang Yijian, Yang Xuejin, Cao Meili, Li Jie
College of Mechanical Engineering, Wuhan Polytechnic University, Wuhan 430048, China.
State Key Laboratory of Material Processing and Die & Mould Technology, Wuhan 430074, China.
Materials (Basel). 2023 Aug 18;16(16):5682. doi: 10.3390/ma16165682.
Mo, TiH, Al and graphite elemental powders were used as starting materials for the activation reaction sintering process, which was employed to fabricate porous MoTiAlC. The alteration of phase constitution, volume expansion, porosity, pore size and surface morphology of porous MoTiAlC with sintering temperatures ranging from 700 °C to 1500 °C were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and pore size tester. Both the pore formation mechanism and activation reaction process at each temperature stage were investigated. The experimental results illustrate that the sintered discs of porous MoTiAlC exhibit obvious volume expansion and pore structure change during the sintering process. Before 1300 °C, the volume expansion rate and porosity increase with the increment of temperature. However, with the sintering temperature above 1300 °C, the volume expansion rate and porosity decrease. At the final sintering temperature of 1500 °C, porous MoTiAlC with a volume expansion rate of 35.74%, overall porosity of 47.1%, and uniform pore structure was synthesized. The pore-forming mechanism of porous MoTiAlC is discussed, and the evolution of pressed pores, the removal of molding agents, the decomposition of TiH, and the Kirkendall effect caused by different diffusion rates of elements in the diffusion reaction are all accountable for the formation of pores.
采用Mo、TiH、Al和石墨元素粉末作为活化反应烧结工艺的起始原料，用于制备多孔MoTiAlC。通过X射线衍射（XRD）、扫描电子显微镜（SEM）和孔径测试仪对烧结温度在700℃至1500℃范围内的多孔MoTiAlC的相组成变化、体积膨胀、孔隙率、孔径和表面形貌进行了表征。研究了每个温度阶段的成孔机理和活化反应过程。实验结果表明，多孔MoTiAlC的烧结盘在烧结过程中表现出明显的体积膨胀和孔结构变化。在1300℃之前，体积膨胀率和孔隙率随温度升高而增加。然而，当烧结温度高于1300℃时，体积膨胀率和孔隙率降低。在1500℃的最终烧结温度下，合成了体积膨胀率为35.74%、总孔隙率为47.1%且孔结构均匀的多孔MoTiAlC。讨论了多孔MoTiAlC的成孔机理，压制孔隙的演变、成型剂的去除、TiH的分解以及扩散反应中元素不同扩散速率引起的柯肯达尔效应均是孔隙形成的原因。
