Influences of Al metal and Al-Si alloys on in-situ synthesis of SiC nanowhiskers in porous Al2O3-SiC composites obtained by carbothermal reduction
Influences of Al metal and Al-Si alloys on in-situ synthesis of SiC nanowhiskers in porous Al2O3-SiC composites obtained by carbothermal reduction
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DOI：
10.1016/j.jallcom.2020.157182
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发表时间：
2021-02-15
影响因子：
6.2
通讯作者：
Miao, Lifeng
中科院分区：
文献类型：
--
作者：
Lao, Xinbin;Xu, Xiaoyang;Miao, Lifeng
纳米SiC晶须是提高多孔Al 2 O3-SiC复合材料强度和抗热震性的良好增强相。本工作以Al和Al-Si合金为还原剂，在碳热还原法制备的多孔Al 2 O3-SiC复合材料中原位合成SiC纳米晶须。采用XRD、SEM、TEM等手段研究了Al金属和Al-Si合金对多孔Al 2 O3-SiC复合材料的相组成、显微结构、孔隙率和强度的影响。结果表明，Al金属和Al-Si合金的加入有效地促进了碳热还原反应，使β-SiC相的合成温度由原来的1500 ℃ ~ 1400 ℃降低。使用Al金属和Al-Si合金在1500摄氏度的相对低温下原位合成了SiC纳米晶须。Al金属和Al-Si合金通过减少孔隙数量和提高SiC晶须的产率有效地提高了多孔复合材料的强度。添加Al 2 O3合金的试样，β-SiC的产率最高，为23.2%，抗弯强度最高，为5 MPa。原位合成的SiC纳米晶须有效地提高了多孔复合材料的抗热震性。在热震试验（室温至1100 ℃）过程中，SiC纳米晶须的氧化可使多孔复合材料的显微结构致密化，增加莫来石含量，从而使多孔复合材料的抗弯强度提高到6.3MPa。(C)2020爱思唯尔B. V.保留所有权利。
SiC nanowhiskers are good reinforcing phases for enhancing the strength and thermal shock resistance of porous Al2O3-SiC composites. In this work, Al metal and Al-Si alloys were used as reducing agents to assist the in-situ synthesis of SiC nanowhiskers in the porous Al2O3-SiC composites prepared by carbothermal reduction method. The influences of Al metal and Al-Si alloys on the phase composition, microstructure, porosity and strength of the porous Al2O3-SiC composites were studied by XRD, SEM, TEM, etc. The results indicate that the use of Al metal and Al-Si alloys effectively promoted the carbothermal reduction and decreased the synthesis temperature of beta-SiC phase from the original 1500 degrees C-1400 degrees C. SiC nanowhiskers were in-situ synthesized at a relatively low temperature of 1500 degrees C with the use of Al metal and Al-Si alloys. Al metal and Al-Si alloys effectively enhanced the strength of the porous composites by reducing the amount of pores and increasing the yield of SiC nanowhiskers. The samples that were added with Al2O3 alloy obtained the highest beta-SiC yield of 23.2% and the highest flexural strength of 5 MPa. The thermal shock resistance of the porous composites was effectively enhanced by the in-situ synthesis of SiC nanowhiskers. The oxidation of SiC nanowhiskers during the thermal shock tests (room temperature to 1100 degrees C) could improve the flexural strength of the porous composites to 6.3 MPa by densifying the microstructure and increasing mullite content. (C) 2020 Elsevier B.V. All rights reserved.