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Double wall carbon nanotubes (DWCNTs) have proven to have a very good structural stability when exposed to high static pressures. We report here on the study of DWCNTs after application of shock wave (dynamic) compression up to 36 GPa in a recovery assembly. TEM images of so‐treated samples reveal a threshold between 19 and 26 GPa of shock wave compression above which significant structural damage is induced whereas only minor damage can be detected below. The threshold detected with TEM coincides well with the collapse pressure of DWCNTs previously reported [You et al., High Press. Res. 31, 186 (2011); Aguiar et al., Phys. Chem. C 115, 5378 (2011)]. Raman data demonstrate a gradual accumulation of structural defects via an increase in D‐band to G‐band intensity ratio (ID/IG‐ratio) from ∼0.2 to ∼0.8 in going from the source CNT material to the nanotubes after compression to 36 GPa. Despite severe damage; the DWCNTs exposed to 36 GPa of shock wave compression survived which is evidenced by Raman spectra. The DWCNTs demonstrate a higher susceptibility to structural damage under dynamic than static pressure.

Axially symmetric flows with converging shock waves in conical solid targets of steel or lead filled by porous aluminum, graphite, or polytetrafluoroethylene under impact of an aluminum plate with the velocity from 2.5 to 9 km/s have been simulated numerically in the framework of the model of the hypoelastic ideal-plastic solid. Equations of state for all materials in question are used to describe thermodynamic properties of the impactor and target over a wide range of pressures and temperatures, taking into account phase transitions. The graphite-to-diamond transformation is taken into consideration based on a kinetic model. Three different convergent cone configurations of the targets either with a closed cavity or with an outlet hole are analyzed. An appreciable increase of the pressure and temperature within the target cavity as well as of the ejected material velocity on decreasing the initial density of a sample is demonstrated in the simulations. Numerical results that can be compared with possible further experiments for verification of the predictions are presented and discussed.

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