Ceramics with grain sizes in the nanometer range tend to have exceptional mechanical, optical and electrical properties breaking new ground for progress in structural and functional applications. Besides the necessity of obtaining homogeneous packing of nanoparticles, which are very prone to agglomeration, ceramists may practice lengthy multiple-step sintering or application of pressure combined with fast heating rates necessary to bypass/limit grain growth (coarsening) and facilitate densification.

Scientists at the Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, Sweden and at the Department for Nanostructured Materials, Jožef Stefan Institute, Ljubljana, Slovenia have showed how the homogeneously packed zirconia (3YSZ) nanoparticle aggregates can be sintered very rapidly to yield relatively dense nanoceramics in the absence of extensive diffusion processes and externally applied pressures. In their recently published work they show a direct evidence of unique densification mechanisms of nanoparticle rearrangement, i.e., coalescence and sliding, a type of particle interactions that were only possible to observe early in colloidal systems, shading more light on nanoparticle behaviour when swiftly exposed to higher temperatures and pushed far from equilibrium.

When exposed to intense electromagnetic radiation of a static graphite crucible in a spark-plasma-sintering (SPS) set-up, providing rapid heating at 250 °C/min, packed nanoparticle aggregates were subjected to rigorous agglomeration, coalescence and sliding, providing densification with no grain growth until close packing in the sintering body was attained. In this way nanoceramics exhibiting 91 % of theoretical density was prepared at 1300 °C with only 2 minutes of dwell time.

The work published in the Scientific Reports open access journal.

Kocjan, A., Logar., and Shen, Z., The agglomeration, coalescence and sliding of nanoparticles, leading to the rapid sintering of zirconia nanoceramics. Scientific Reports (2017) DOI: 10.1038/s41598-017-02760-7

www.nature.com/articles/s41598-017-02760-7


 

Contacts:

Assistant Professor Andraž Kocjan (postdoc at MMK in the 2011-2013 period)

Department for Nanostructured Materials, Jožef Stefan Institute, Ljubljana, Slovenia

(a.kocjan@ijs.si)


 

Professor Zhijan (James) Shen

Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, Sweden

(shen@mmk.su.se)