On the use of autocorrelation functions, permeability tensors, and computed tomography to characterise the anisotropy of diesel particulate filter materials

Dominique Bernard (1) , Fabien Léonard (2) , Erwan Plougonven (3) , Giovanni Bruno (2, 4)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 BAM Bundesanstalt für Materialforschung u. -prüfung
3 Université de Liège
4 University of Potsdam = Universität Potsdam

We show how the combination of the spatial autocorrelation function and permeability calculations, applied to 3D X-ray computed tomography data, can yield quantitative information on the anisotropy of both meso-structure and fluid flow in Diesel Particulate Filter (DPF) materials, such as Cordierite and SiC. It was found that both the degree of anisotropy, and the orientation of the permeability and meso-structure are similar, but not identical. We confirm that the morphological anisotropy of cordierite materials is weak, and clearly influenced by the extrusion process that determines the main direction of anisotropy. Properties of the autocorrelation function are discussed and it is shown why estimating the characteristic length of real meso-structures (grain or ‘pore’ size) is not possible. Finally, we show that the autocorrelation function applied on grey-level images can give a good estimate of the degree of anisotropy even with limited resolution.

Mots clés: Anisotropy; Autocorrelation function; Computed tomography; Permeability tensor; Diesel particulates filter; Ceramics

Domaines: Matériaux

Dominique Bernard, Fabien Léonard, Erwan Plougonven, Giovanni Bruno. On the use of autocorrelation functions, permeability tensors, and computed tomography to characterise the anisotropy of diesel particulate filter materials. Philosophical Magazine, 2020, 100 (22), pp.2802-2835. ⟨10.1080/14786435.2020.1798532⟩. ⟨hal-02947931⟩