Simulation of micro-crack formation in a magnesia spinel refractory during the production process

Refractory brittleness is often reduced by the introduction of micro-cracks during the production process. Using the finite element method, crack initiation and formation in a magnesia-spinel refractory during the cooling stage of the firing process are simulated in a 2D representative volume element. The microstructure is described by a random spatial distribution of spinel and magnesia grains surrounded by a magnesia matrix. The grain size distribution was chosen according to the Dinger-Funk equation. Crack formation due to a thermal misfit between the magnesia and spinel phases was evaluated using the concrete damaged plasticity model in ABAQUS. After cooling, the model displayed reduced brittleness and a crack pattern typical of this type of material. The obtained mechanical properties from the subsequently simulated tensile test were compared with literature values. The simulation provided reasonable values and is capable of reproducing micro-cracking in the presented refractory.