Sintering behavior and thermal shock resistance of aluminum titanate (Al2TiO5)-toughened MgO-based ceramics

Remarkable Structural Modifications of Tialite Solid Solutions Obtained by Different Methods

“…This observation suggests that the sintered polycrystal may exhibit low strength. The problem of improving the mechanical parameters of tialite-made polycrystals is now widely discussed in the literature [ 20 , 21 , 27 ].…”

“…A careful analysis of Figure 2 , Figure 3 and Figure 4 , which shows the changes in the lattice parameters (a, b and c), reveals their increase in the systems with the additives compared to the parameters of the elementary tialite cells without any additives (AT). From the point of view of stability, the increase in the value of parameter a is important; due to this increase, the deformation of oxygen octahedra, forming the tialite structure, reduced, the stresses associated with differences in the thermal expansion of the differently oriented grains reduced, fewer micro-cracks formed, and the structure of the MAT solid solutions showed higher stability [ 1 , 27 , 30 , 33 ]. It is still worth noting that the increase in the reaction sintering temperature of the tialite or its MAT solid solutions and the associated increase in the synthesis yield resulted in a slight increase in the value of the lattice parameter a, with a slight decrease in the values of the parameters b and c, which can be explained by the formation of the proper structure of the tialite or MAT solid solutions.…”

“…It can also be seen that the differences in the values of the lattice parameters of the systems with and without silica were negligible when compared to the significant increase in the values of these parameters, relative to the reference system. These observations suggest that silicon does not build into the structure of tialite, while nanosilica forms a kind of “diffusion barrier” on the grain boundaries, limiting the grain size, reducing the number of micro-cracks formed, and decreasing the susceptibility to thermal decomposition, while, on the other hand, hindering the incorporation of Mg 2+ cations into the structure of aluminum titanate [ 1 , 19 , 27 , 30 , 33 ]. These suggestions were confirmed by the surface phase composition analysis, according to which silicon-rich phases were present at the grain boundaries, at triple points, and between the obtuse grains of the tialite ( Figure 9 ).…”

“…As a result of the formation of a complex stress state in the material, micro and macro cracks are formed in the material during its cooling after reaction sintering [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. These cracks provide desirable properties, such as a low macroscopic thermal expansion coefficient [ 22 ], low thermal conductivity [ 23 , 24 , 25 ], and, thus, high resistance to thermal shock [ 1 , 11 , 26 , 27 ]. Tialite also has high resistance to microcrack propagation [ 28 ].…”