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The fabrication of ceramic components with controlled porosity often requires using pore formers. This paper shows how modeling can help in optimizing pore former quantity and size with respect to sintering behavior and material properties. The case of a mixed ion-electron conductor SOFC cathode is considered. Numerical simulations based on the discrete element method are performed to mimic the sintering of Nd 2 NiO 4 ceramic powders processed with various fractions of pore formers (0–40%) and size ratios (1–5 times the size of ceramic particles). From the results of these simulations, the effect of pore former particle size and amount on sintering densification, conductivity and effective surface area is analyzed. Experiments achieved on a Nd 2 NiO 4 powder with miscellaneous pore formers confirm simulation outcomes as the minor effect of the pore former particle size ratio on the density and the presence of an optimum of oxygen adsorption for 20 vol.%. [ABSTRACT FROM AUTHOR]

Abstract: In a companion paper (Part I), the processing of two-layer parts by co-sintering of two powder blends has been investigated. As a complement to this experimental study, a finite element simulation of this operation has been achieved. This simulation was based on constitutive equations identified from specific experiments performed with each blend. The numerical results provided deformation and internal stress information that have been found to be fully consistent with the experimental observation. In particular they confirm that cracking occurs in the course of heating, when one material starts densifying and the other one is still brittle, whereas a large densification mismatch at high temperature is not harmful because the low viscosity of both materials leads to the relaxation of internal stresses. [Copyright &y& Elsevier]