Viscoelastic toughening of aluminosilicate refractory ceramics

Thermal Shock Resistance of a Kyanite-Based (Aluminosilicate) Ceramic

“…Baker et al [6] have also presented a fully consistent viscoelastic bridging model in which the viscous bridging stress is a function of the Crack Opening Displacement (COD), u(z,t), and the rate of change of the COD, Á u z; t ð Þ. This gives the viscous bridging stress as:…”

“…Under large-scale bridging conditions, fully consistent solutions of the viscoelastic toughening levels have been derived by Baker et al [6]. For a single straight mode I crack of length a, if we assume that the temperature and stress distributions are insensitive to the presence of the crack, the stress intensity factor at the crack tip (that arises from the thermal shock) is given by the following expression [6]:…”

“…Fracture mechanics models have also been used [5,6] to quantify the viscoelastic toughening of ceramics materials subjected to high temperatures. These models incorporate the material properties, the microstructure variables, and the details of the viscoelastic bridges [ Fig.…”

“…These models have been applied to the study of thermal shock in layered mullite and silica-containing structures in which viscoelastic tractions are applied to cracks through uncracked ligament bridges behind the crack-tip [5,6]. These give rise to shielding components that can be controlled by doping with sodium oxide (Na 2 O) and calcium oxide (CaO) to vary the viscosity-temperature characteristics [5].…”

“…In recent years, significant efforts have been made to develop fracture mechanics approaches for the modeling of thermal shock-induced crack growth [1][2][3][4][5] and crack-tip shielding [6] under thermal shock conditions. These models have been applied to the study of thermal shock in layered mullite and silica-containing structures in which viscoelastic tractions are applied to cracks through uncracked ligament bridges behind the crack-tip [5,6].…”