Julian Esper, M. Sc.
The mechanical response of homogeneous bulk materials to external stimuli can be described by the constitute laws of continuum mechanics. However, for example, SiO2 glass exhibits a brittle-to-ductile transition at smaller particle sizes (< 800 nm) resulting in unique mechanical properties. The addition of different glass network modifiers can influence the macroscopic material response dramatically and has not been investigated on the (sub-) micron level. Especially in the field of particle technology, where single particle properties govern the final product properties, the mechanical deformation behavior if individual micron-sized particles is of great interest [1,2].
Within this context, structurally and morphologically well-defined particulate glass systems are characterized over a broad particle size range by complementary in situ compression experiments in a scanning electron microscopy. Mechanical testing is performed in a SEM- supported manipulation device  which allows for a statistical evaluation of different mechanical quantities such as Young’s modulus, breakage probability and brittle-to-ductile transition.
Fig. 1: Stress-strain curve of a soda lime glass particle (SiLi Beads, Fa. Sigmund Lindner, Germany) (A) and particle size dependant mechanical behavior of soda lime glass (B). Corresponding SEM images of a 1.8 µm soda lime glass particle at different stages of compression (C).
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 J. Paul et al., Powder Technology 286 (2015) 706.
 S. Romeis et al., Review of Scientific Instruments 83 (2012) 95105.