Cold Sintering of ceramic-polymers composite: using polymer as an active component during sintering

Cold Sintering Process (CSP) has proven its efficiency at sintering ceramics at temperatures below the decomposition temperatures of some polymers. This enables to process ceramic-polymer composites with high ceramic content... [ view full abstract ]

Cold Sintering Process (CSP) has proven its efficiency at sintering ceramics at temperatures below the decomposition temperatures of some polymers. This enables to process ceramic-polymer composites with high ceramic content (typically > 50 vol.%), which are impossible to obtain through other methods. Varistor system could be obtained by sintering ZnO and polytetrafluoroethylene (PTFE) with less than 10 vol.% polymers within a few minutes at temperatures below 300 ˚C [1]. In such system, polymer phase was considered as passive component since ZnO is the main phase undergoing sintering, while PTFE deforms and fills grain boundaries. Recent investigations on sintering mechanisms highlighted the effect of polymer phase as an active component during sintering, promoting highly anisotropic grain growth for the ceramic phase. This observation was correlated to the evolution of anisotropic electrical conductivity with polymer content increase. The aim of this presentation is to show a comparison between sintering mechanisms of pure ZnO and ZnO-PTFE composite materials, but also the influence on its properties. Using polymer to control ceramic grain growth during CSP is an original way  of preparing highly oriented microstructures, thus, properties.

[1] X. Zhao et al. Adv. Eng. Mater. (2018) 1700902