Characterisation of elementary sintering processes using Monte Carlo simulation and X-ray computed microtomography

摘要

The sintering behaviour of a glass powder compact has been investigated at the grain scale using X-Ray computed microtomography (XCMT) and Monte Carlo simulation. XCMT is a non-destructive 3D characterisation technique that have provided, in our case, a series of 3D images of the morphological evolution during sintering of the same grain set. It has been possible to extract from these images the neck growth kinetics. This result has been compared to the numerical result for the two-particle system produced by a newly developed Monte Carlo methodology. Unlike other calculations based on the Potts model, this methodology minimises a non-discrete energetical potential including real surface energies as well as the elastic energy of the particles. Using suitable stochastic changes of the particle configuration, minimisation enables both the quantification of the capillary induced stress gradient within the particles, and the statistical resolution of the mass transport in relation to this gradient. Starting from the experimental sintering temperature T, and using the glass physical properties, the sintering kinetics has been simulated and directly compared to experimental data extracted from XCMT images. It is shown that the Monte Carlo procedure has succeeded in predicting the experimental neck growth evolution until 85% of the compact density. This evolution, clearly different from a Newtonian viscous sintering that is generally expected for glasses, is instead characteristic of a viscoelastic behaviour of the particles. In regard to that point, the interest of the developed Monte Carlo methodology is clearly demonstrated since the rheological behaviour of the particle is not predetermined at all, but implicitly generated.