One-step functionally graded materials fabrication using ultra-large temperature gradients obtained through finite element analysis of field-assisted sintering technique

Abstract

Functionally graded materials (FGMs) exhibit good performance owing to their gradual and directional property and compositional changes occurring in the material. Field-assisted sintering is one method to fabricate FGMs by utilizing a heating geometry that provides a temperature gradient within the sample. Here, a heating geometry that provides ultra-large temperature gradients is proposed. Using finite element analyses, the geometrical parameters of the proposed design were optimized through a systematic parametric investigation. The resulting temperature gradients were evaluated for electrically conductive stainless steel (SUS) 304L and insulating 8 mol% yttria-stabilized zirconia (8YSZ). The temperature gradients within the samples were 80 and 122 °C/mm for SUS 304L and 8YSZ, respectively. The heating geometry was used to fabricate functionally graded versions of the two materials, which showed gradual changes in the porosities, grain sizes, and hardness. Lastly, the temperature gradients were then quantitatively validated through temperature measurements and single-temperature sintering experiments.