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Current demands in the economic and environmental aspects of the industry require more and more research and development in different areas. As scientists and engineers in the field of ceramics, one of the areas which we all recognize as currently problematic is the field of ceramic sintering, due to the largely associated energy consumption and CO2 emissions. The need to change the conventional methods of ceramic sintering has opened the door for many different techniques to appear, with emphasis on FLASH sintering, Spark Plasma Sintering, or the Cold Sintering Process.

One of the latest techniques to appear was the Ultrafast High-temperature Sintering (UHS), where the conventional process is substituted by an extremely rapid heating of the ceramic. The heating process is caused by large amounts of energy dissipation in a carbon felt material, which translates to heating rates between 103 and 104 °C. This characteristic, together with the simplicity and versatility of the technique caught the attention of the sintering researchers around the world, with many different tests performed in various materials to help understand the potential of UHS.

Our work aims to expand the knowledge of UHS, by focusing on a specific material of high interest to our research group: potassium-sodium niobate (KNN), a possible non-toxic candidate for the substitution of lead-based piezoelectric ceramics. KNN’s current processing problems focus on the bad sinterability of the material and the difficulties to maintain the alkali elements in its structure. These obstacles seem to align with the strengths of UHS, as the technique allows for a high densification with a fine microstructure, and the short sintering times prevent the evaporation of volatile compounds.

Initial experiments have shown densification values of KNN up to 90 % through UHS, with a future work envisioning the possibility of finding the ideal conditions to process potassium sodium niobate through this route. Besides that, some other optimization problems will need to be addressed, such as the presence of carbon contamination in UHSed materials and the evaluation of KNN’s dielectrical properties. Still, I believe we are taking a step in the right direction, towards the study and development of a technology with a lot of potential to impact both the laboratorial and industrial aspects of ceramic production.

João L. Miranda

j.miranda@ua.pt

LinkedIn

ResearchGate

Electroceramics Group

CICECO-Aveiro Institute of Materials

University of Aveiro

Aveiro

Portugal