Thermal shock resistivity of hybrid carbon foam materials: Experiments and model predictions

This work presents computational solutions and experimental results on the most important parameters influencing thermal shock. The focus lies on the thermal shock parameters of hybrid carbon foams reinforced with yttria-stabilized zirconia (YSZ) and silicon carbide (SiC) coatings as well as MgO matrix composites under thermal and mechanical load. The computational approach is related to the quantification of failure stresses as a function of structural foam parameters (e.g. cell size, strut diameter, and strut length) using a microstructurally based finite element analysis. Similar to the early stages of thermomechanical modeling of refractories, the MgO-C hybrid foam is modeled by linear elasticity. The maximal occurring tensile stresses are used as a failure criterion. For the first time, numerical results of this simplified computational approach are correlated to the experimentally motivated extended Hasselman's equations. Based on the numerical simulation of the Hasselman relation it is shown, that crack initiation under thermal shock loading could be simulated with this simplified only linear elastic approach, outlined in this work. Along with the computational investigation of the influence of microstructural parameters on the thermal shock resistivity, the experimental results, e.g. the parameters of final crack length and the final crack densities, make it possible to draw conclusions about the microstructural foam parameters that are the most suitable to achieve advanced thermal shock characteristics of next generation hybrid carbon foam refractories.