Research articleExamining mechanisms of metallurgical coke fracture using micro-CT imaging and analysis

- Micro-CT imaging was applied to examine coke microstructure at high resolution.
- The 3D rendered microstructure was used as the input in finite element analysis.
- 3D von Mises stress maps showed regions of high stress concentration in the coke.
- The coke was stressed to breaking point under mixed mode loading and imaged again.
- Correspondence between calculated and actual high stress points was demonstrated.

Micro-CT imaging of samples of metallurgical coke was achieved at high resolution (~ 10 μm), using the Imaging and Medical Beamline of the Australian Synchrotron. The coke samples were then stressed to breaking point and imaged again. The result is that we can examine, in fine detail in 3D, the locations of the fracture surfaces in the coke, and their relationship to the different aspects of the microstructure. In addition, we have performed 3D finite element linear elasticity analysis, using the microstructure of the cokes as input to the calculations. The result is a 3D map of the von Mises stress in the structure, which provides information about the likely locations of fracture. Finally, we have performed a fractographic analysis of the fracture surfaces, in order to characterise the nature of the fracture mechanisms. The imaging and analysis has been performed for both compressive and mixed-mode loading of the coke samples. The work provides the opportunity to identify the key mechanisms for fracturing of coke due to the aspects of their microstructure, and has the potential to aid in the production of stronger metallurgical coke, by means of blending coals to produce coke with improved strength properties.