Fabrication and mechanical properties of low‐temperature sintered Al₂TiO₅ flexible ceramics

Abstract

To lower the sintering temperature and improve the mechanical properties of aluminum titanate (AT, Al2TiO5) flexible ceramics, γ‐Al2O3 is employed to partially replace the α‐Al2O3 as the starting powder. The results show that the addition of γ‐Al2O3 is sufficient to promote the reaction, improve the flexibility, raise the strength, and accelerate the grain growth of AT flexible ceramics when sintered at 1300°C. With that, the combination of optimum fracture strength (∼33.52 MPa) and high flexibility (∼1.05%) is obtained when the addition of γ‐Al2O3 is 20 wt.%. As compared to the virgin, the optimization of 21.67% in fracture strength and 176% in strain can be obtained. It is believed that the increase of crack deflection and branching should take the responsibility. However, the mechanical strength degrades with the increase of sintering temperature, which is caused by the grain defects that reduce the bearing capacity of AT grains and lead to the grain fracture model transition. In addition, the effect of γ‐Al2O3 content on AT grain growth transfers from promotion to inhibition with the increase of sintering temperature. The main reason is that the growth of the nanocrystals at AT grain boundary causes the uneven distribution of the intermediate phase, leading to the roughening transition of the boundary and hence reducing the grain growth rate. On these bases, the grain growth mechanism that dominates by grain boundary is proposed. It is believed that the discovery of this study will provide a new grain growth model and the reference for solving the abnormal grain growth or grain growth stagnation.