Sintering driving force of Al2O3 powders at the initial stage of pulse electric current sintering under thermoelastic diffusion

Abstract

Abstract Background The theoretical investigation of the rapid sintering mechanism under pulse electric current sintering has no unified understanding. Especially for non-conductive powder, since there is no current flowing directly through the powder materials, the driving force in the neck growth mechanism becomes a key problem and needs to make progress. Methods The sintering driving force of nonconductive Al2O3 powders at the initial stage of pulse electric current sintering is investigated under the thermoelastic diffusion coupling transmission with the consideration of non-Fourier and non-Fick effect. Results The concentration diffusion flux, which is caused by the local concentration gradient, and the thermal diffusion flux act as additional driving forces for the surface curvature driving. Conclusions Equal-sized particles model reveals that these fluxes exert the dominant influence on sintering driving force for volume and simultaneous surface and volume diffusion mechanisms. In particular, the sintering driving force is remarkably increased at the postperiod of the initial stage of sintering.

Keywords

• Pulse electric current sintering
• Sintering driving force
• Generalized thermoelastic diffusion
• Thermal diffusion flux