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In situ microstructure characterization of potassium di-phosphate (KDP) densification during cold sintering



Andrew J. Allen, Russell Maier, Fan Zhang, Ivan Kuzmenko, Jan Ilavsky


In order for ceramic additive manufacturing (AM) to achieve its full potential, it is increasingly important to develop a more rigorous understanding of fundamental phenomena that govern the kinetics and thermodynamics of ceramic AM processes. For some AM build processes, such as direct ink write (DIW) and ceramic extrusion, methods for densifying the resulting green-body product need to be considered to complement the efficiencies of ceramics AM, itself. One densifi-cation route, at least for planar geometries, is offered by the recently developed cold sintering process (CSP), whereby high-density final product is achieved through addition of a small amount of liquid solvent and application of modest uniaxial compressive stress at relatively low temperature. We have applied in situ small-angle X-ray scattering (SAXS) methods and X-ray diffraction (XRD) to characterize and quantify the pore morphology evolution during CSP for a model system: KH2PO4 (KDP). We show that both temperature and applied stress affect the densi-fication rate in CSP, but stress has a stronger effect on the evolving morphology. An approximate linear densification rate regime can be identified, from which an effective densification activation energy of ≈ 90 kJ/mol can be deduced.
Applied Sciences


additive manufacturing, cold sintering process, ceramic densification, microstructure characterization, X-ray scattering, materials and process characterization tools


Allen, A. , Maier, R. , Zhang, F. , Kuzmenko, I. and Ilavsky, J. (2022), In situ microstructure characterization of potassium di-phosphate (KDP) densification during cold sintering, Applied Sciences, [online],, (Accessed May 29, 2024)


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Created October 19, 2022, Updated November 29, 2022