The effect of axial impact on thin-walled circular tubes, which are reinforced externally by a glass fibre reinforced plastic (FRP) composite, is studied in this paper. The influence of circumferential reinforcement on the static and dynamic crushing behaviour of steel tubes is examined. The experimental results show that the crushing mode depends strongly on the circumferential reinforcement. All the reinforced tubes collapsed in a diamond mode with more intensive lobes than the corresponding non-reinforced ones under quasi-static loading conditions. In the dynamic case, for slightly reinforced tubes, the dynamic effect on the crushing mode is not evident, whereas for strongly reinforced tubes, they collapsed in an ‘internal inversion’ mode, which did not appear in the static case.

This study is aimed to synthesize ZrB2–SiC composite powders by boro-carbothermal reduction of zircon using two different carbon sources, namely expanded graphite and carbon black. The effect of carbon sources on the phase composition and microstructure of composite powders was studied using an X-ray diffractometer, a scanning electron microscope, and an energy spectrum analyzer. Pure-phase ZrB2–SiC composite powders were prepared in 2 h at 1550 and 1500 °C 1500 °C using expanded graphite and carbon black, respectively. In the former case, anisotropic ZrB2–SiC composite powders were synthesized. Their ZrB2phase grains had an average diameter of 2.0 μm and regular hexagonal shape, while SiC phase grains were whisker-shaped, had an average diameter of 0.15 μm and aspect ratio exceeding 20. For carbon black, finer ZrB2grains and shorter rod-shaped SiC grains were obtained.