Quantitative X-ray microtomography technique to evaluate high-temperature transient diffusion of Iron diffusants in high alumina-silicate porous refractory media

Diffusion tests were performed with solid diffusants of Iron oxides in contact with porous silico-aluminous refractory castables in high-temperature conditions. A non-destructive X-ray computer microtomography technique with digital 3D reconstruction (3DμCT) was used for spatial monitoring the diffusion into the media. A particle tracking (PT) method was applied to evaluate diffusion through porous materials and to quantify its diffusive properties based on 3D images over time. The influence of temperature was examined in the range from 1100°C to 1300°C. Each sample was heat treated for 100h in the investigated temperature. The normalized concentration of diffusants as a function of the penetration was obtained by 3DμCT images and compared with the concentration profile determined by elementary microanalysis with energy dispersive spectroscopy and surface chemical mapping (MAP/EDS). Thus, the diffusivity of the porous media was quantified from the experimental data. It was observed a variation less than 3.52% between the MAP/EDS and 3DμCT, i.e., between the destructive and non-destructive methods, suggesting that the 3DμCT method may be extended to other media and diffusants.