SiC对反应烧结多孔Al2TiO5的物相及组织性能影响

本研究以γ-AlOOH、TiO₂和SiC为原料, 通过无压反应烧结制备了Al₂TiO₅多孔材料, 分析比较了SiC粒度和含量对合成产物的物相组成、显微组织、抗压强度、孔隙率和孔径分布的影响。结果表明: 反应产物的物相组成为Al₂TiO₅、Al₆Si2O₁₃、TiC、SiO₂和Al₂O₃, 还有少量未反应的TiO₂。SiC与TiO₂反应生成TiC和SiO₂, TiC颗粒弥散分布于多孔材料壁面或者骨架中, 而SiO₂进一步与γ-AlOOH分解出的Al2O3反应生成Al₆Si₂O₁₃晶须, 晶须交错分布于Al₂TiO₅颗粒之间或者孔洞中, 与TiC颗粒一起提高复合材料的抗压强度, 特别是采用小粒径SiC时, 对抗压强度的改善效果更加显著; 添加大粒径SiC后, 改变原有颗粒堆积状态, 可提高复合材料的孔隙率。但当SiC含量超过5wt%时, 因为生成较多低熔点的SiO₂, 部分填充于多孔材料的孔隙中, 部分则分布于Al₂TiO₅晶粒之间, 既减小孔隙率, 又降低晶粒间结合强度和试样的抗压强度。

Effects of SiC on Phases,Microstructure and Mechanical Property of Porous Al2TiO5 Fabricated by Reaction Sintering

Porous aluminium titanate (AT) composites were fabricated by sintering with γ-AlOOH, TiO₂ and SiC as raw materials. Effects of the particle size and the content of SiC on phases, microstructures, compressive strength, porosity and pore size distribution of products were investigated. Results show that the phases of the products are composed of Al₂TiO₅(AT), Al₆Si₂O₁₃, TiC, SiO₂, Al₂O₃ and a small amount of unreacted TiO₂. When SiC is added into γ-AlOOH and TiO₂ mixture, it reacts with TiO₂ and forms TiC and SiO₂. The small TiC particles distribute and disperse in the walls and shelves of porous products. Moreover, SiO₂ reacts with Al₂O₃, decomposted from γ-AlOOH, to form Al₆Si₂O₁₃ whiskers which distribute crisscross between Al₂TiO₅ grains or in the pores. The Al₆Si₂O₁₃ whiskers along with TiC particles contribute greatly to improving the compressive strength of the products, particularly with small SiC particles. When SiC particles are big, the packing patterns of powder mixtures are changed and the porosities of the products are increased. However, when SiC content is beyond 5wt%, both the porosities and compressive strength of the products decrease due to the formation of more low-melting point SiO₂, and some SiO₂ fills in the pores of the porous products, and some exists on the surface of Al₂TiO₅ grains and weakens the bonding strength.