Characterization of Prebake Anodes by Micro X-ray Computed Tomography

As part of the continuous work in improving anode quality at Hydro Aluminium, series of pilot scale anodes have been manufactured with systematic changes in coke type and green paste production including recipe. The anodes also support M.Sc., Ph.D. and PostDoc work in programs supported by Hydro and the Norwegian Research Council. In addition to regular analysis, the pore, void and grain distribution has been investigated using Micro X-ray Computed Tomography (mu CT). This non-destructive 3D imaging is now implemented at a cost to allow larger numbers of samples, and a methodology has been developed by SINTEF that yields surprising sharp detail, suited to interpret important structural factors for relatively large anode volumes of 10-130 mm diameter. Given a better cost to information yield than image analysis and mercury porosimetry, Hydro will continue to support academic work with CT analysis. Examples will be shown of baked anodes before and after electrolysis testing plus crack patterns after mechanical testing.