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Synthesis, microstructure, and properties of high purity Mo 2 TiAlC 2 ceramics fabricated by spark plasma sintering
Journal of Advanced Ceramics ( IF 18.6 ) Pub Date : 2020-12-23 , DOI: 10.1007/s40145-020-0412-7
Yunhui Niu , Shuai Fu , Kuibao Zhang , Bo Dai , Haibin Zhang , Salvatore Grasso , Chunfeng Hu

The synthesis, microstructure, and properties of high purity dense bulk Mo2TiAlC2 ceramics were studied. High purity Mo2TiAlC2 powder was synthesized at 1873 K starting from Mo, Ti, Al, and graphite powders with a molar ratio of 2:1:1.25:2. The synthesis mechanism of Mo2TiAlC2 was explored by analyzing the compositions of samples sintered at different temperatures. It was found that the Mo2TiAlC2 phase was formed from the reaction among Mo3Al2C, Mo2C, TiC, and C. Dense Mo2TiAlC2 bulk sample was prepared by spark plasma sintering (SPS) at 1673 K under a pressure of 40 MPa. The relative density of the dense sample was 98.3%. The mean grain size was 3.5 μm in length and 1.5 μm in width. The typical layered structure could be clearly observed. The electrical conductivity of Mo2TiAlC2 ceramic measured at the temperature range of 2–300 K decreased from 0.95 × 106 to 0.77 × 106 Ω–1·m–1. Thermal conductivity measured at the temperature range of 300–1273 K decreased from 8.0 to 6.4 W·(m·K)–1. The thermal expansion coefficient (TEC) of Mo2TiAlC2 measured at the temperature of 350–1100 K was calculated as 9.0 × 10–6 K–1. Additionally, the layered structure and fine grain size benefited for excellent mechanical properties of low intrinsic Vickers hardness of 5.2 GPa, high flexural strength of 407.9 MPa, high fracture toughness of 6.5 MPa·m1/2, and high compressive strength of 1079 MPa. Even at the indentation load of 300 N, the residual flexural strength could hold 84% of the value of undamaged one, indicating remarkable damage tolerance. Furthermore, it was confirmed that Mo2TiAlC2 ceramic had a good oxidation resistance below 1200 K in the air.



中文翻译:

火花等离子体烧结制备高纯Mo 2 TiAlC 2陶瓷的合成,微观结构和性能

研究了高纯度致密块体Mo 2 TiAlC 2陶瓷的合成,微观结构和性能。从Mo,Ti,Al和石墨粉末开始,在1873 K下以2:1:1.25:2的摩尔比合成了高纯度Mo 2 TiAlC 2粉末。通过分析在不同温度下烧结的样品的组成,探索了Mo 2 TiAlC 2的合成机理。发现由Mo 3 Al 2 C,Mo 2 C,TiC和C之间的反应形成Mo 2 TiAlC 2相。致密的Mo 2 TiAlC 2通过火花等离子体烧结(SPS)在1673 K和40 MPa的压力下制备块状样品。致密样品的相对密度为98.3%。平均晶粒尺寸为长3.5μm,宽1.5μm。可以清楚地观察到典型的分层结构。在2–300 K的温度范围内测得的Mo 2 TiAlC 2陶瓷的电导率从0.95×10 6降至0.77×10 6 Ω–1·m-1。在300–1273 K的温度范围内测得的热导率从8.0降至6.4 W·(m·K)–1。计算出在350–1100 K的温度下测得的Mo 2 TiAlC 2的热膨胀系数(TEC)为9.0×10 –6K –1。另外,该层状结构和细晶粒尺寸还具有优异的机械性能,例如具有5.2 GPa的低维氏固有硬度,407.9 MPa的高挠曲强度,6.5 MPa·m 1/2的高断裂韧性和1079 MPa的高抗压强度。即使在300 N的压入载荷下,残余抗弯强度也可以保持未损坏的抗弯强度的84%,这表明其显着的损伤耐受性。此外,证实了Mo 2 TiAlC 2陶瓷在空气中低于1200 K具有良好的抗氧化性。

更新日期:2020-12-23
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