Application of refined Digital Image Correlation for the investigation of the fracture behaviour of Magnesia-based refractories

Reference Presenter Authors
14-051 Imad KHLIFI KHLIFI, I.(Université de Limoges); POP, O.(Université de Limoges); DUPRE, J.(Université de Poitiers); DOUMALIN, P.(Université de Poitiers); HUGER, M.(Université de Limoges);

Magnesia-based refractory bricks are used in cement rotary kilns for their ability to sustain thermal induced damage caused by thermal cycling. The flexibility and crack propagation resistance of magnesia is improved by the addition of compounds from the spinel group such as magnesium spinel or iron spinel. As a consequence, a pre-fabricated network of microcracks is generated within the microstructure which leads to a decrease in the elastic energy stored in the material during loading. Additionally, the crack propagation resistance is enhanced thanks to the presence of energy dissipating phenomena in the so-called process zone, which include crack bifurcation and crack branching among other mechanisms.  

The complex fracture behaviour of Magnesia-Spinel materials was investigated in relation to the microstructure of the materials. The Wedge Splitting Test (WST) has been performed on refractory samples to promote stable crack propagation while a camera has been used to record the surface of the specimen during loading. Subsequently, images were processed and then analysed by Two-Parts Digital Image Correlation (2P-DIC), a refined process that was specifically developed to study the fracture behaviour of quasi-brittle materials.

Results highlighted the effectiveness of applying 2P-DIC during WST in the observation of crack propagation with a refined crack spatial resolution. Moreover, this approach has provided a better understanding of fracture mechanisms in magnesia-spinel materials.