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In this study, a novel approach to the explosive synthesis of titanium carbide (TiC) is discussed. Nonstoichiometric TiCx powder was produced via the underwater explosion of a Ti powder encapsulated within a spherical explosive charge. The explosion process, bubble formation, and synthesis process were visualized using high-speed camera imaging. It was concluded that synthesis occurred within the detonation gas during the first expansion/contraction cycle of the bubble, which was accompanied by a strong emission of light. The recovered powders were studied using scanning electron microscopy and X-ray diffraction. Submicron particles were generated during the explosion. An increase in the carbon content of the starting powder resulted in an increase in the carbon content of the final product. No oxide byproducts were observed within the recovered powders. [ABSTRACT FROM AUTHOR]

In order to develop composite materials, new attempting was conducted. When an explosive is exploded in water, underwater shock wave is generated. Metal plate is accelerated by the underwater shock wave and collided with diamond particles at high velocity. In this paper, pure aluminum and magnesium alloy plates are used as matrix. Micro and nano sized diamond particles were used as reinforcement. Micro diamond particles were closely coated on metal surface. Some of micro diamond particles were penetrated into aluminum. Improvement of base metal property (wearing resistance) was verified by wear test for recovering metal plate. In order to confirm the deformation of the aluminum plate during the collision with diamond particles, simplified numerical simulation was conducted by using LS-DYNA software. From the result of numerical simulation, large deformation of aluminum and process of particle penetration were verified. [ABSTRACT FROM AUTHOR]

Vaporizing foil actuator welding is employed to connect dissimilar metals by utilizing the energy of an electrical explosion as the driving force for flyer plate acceleration. Herein, the electrical and chemical energies of explosives were combined to increase flyer plate velocity. A metal foil or wire mesh was used as an actuator, and a small amount of explosives was placed on the foil. Uniform acceleration of the flyer plate on the actuator was recorded using a high-speed video camera. The electrical energy applied to the actuator was measured synchronously by filming. The explosion of chemical explosives was successfully initiated owing to the electrical explosion of the actuator. In all experiments, the combination of the electrical explosion and chemical reaction improved the acceleration of the samples, facilitating higher velocities. The impact of the actuator type (mesh or foil) and the electric discharge parameters on the performance was studied. While foil actuators were more efficient in experiments on electric explosions alone, mesh actuators were superior when the chemical explosive was added. Explosions of the mesh actuator could initiate low density pentaerythritol tetranitrate (PETN) (the space-filling rate of PETN was approximately 30%). An explosive force of 0.3 g of PETN was converted into a driving force, imparting the flying plate with a velocity greater than 210 m/s. Electrical energy consumption for PETN initiation may be assumed to have an insignificant impact on flyer plate acceleration. In future, the proposed method may be used to connect heavier and thicker materials without expensive high-performance capacitors. [Display omitted] • Developed acceleration technique combines electrical and chemical explosions. • High pulsed current was used to initiate the detonation of explosives. • A significant increase in flyer plate velocity was observed. • Uniform acceleration of the flyer plate was observed using high-speed video camera. [ABSTRACT FROM AUTHOR]

Previously, a novel sub-micron shock imprinting technique based on explosive-derived underwater shock waves was developed. In general, an underwater shock wave, whose high-pressure duration is considerably larger than that of laser-induced shock waves, can imprint higher quality sub-micron reliefs from a mold onto a foil surface compared to that achievable through conventional laser shock imprinting. To realize large-area imprinting, the size of the explosives must be increased. However, the detonation of explosives usually starts at one end, and if the dimensions of the explosives are increased, the metal foil may be compressed into a mold by an oblique shock wave. Nevertheless, the imprinting using oblique shock waves has not been examined. Therefore, in this study, a linear explosive was used to generate an oblique underwater shock wave and compress a 10 μm thick Al foil into a plastic mold. The oblique shock wave was evaluated through optical observation using a high-speed video camera and numerical simulation. The recovered reliefs exhibited a molding depth of 62% relative to the mold. The proper placement of the explosives could alleviate the production size limitation. The proposed technique can facilitate the realization of outdoor applications for metasurface materials. [Display omitted] • An underwater explosion generated a shock wave that obliquely impacted an Al foil. • A large-area periodic nanoarray was developed using the oblique underwater shock wave. • Deep grooves were imprinted on a 10 μm thick Al foil. • Presence of an acceleration distance can ensure the realization of a deep trench. [ABSTRACT FROM AUTHOR]

Laser shock imprinting (LSI) is an emerging method for creating sub-micrometer and nanoscale reliefs on thin metal foils. This report proposes using underwater shockwaves, generated by detonating an explosive charge, for high-quality imprinting as an alternative to LSI. The nanoscale relief of a polycarbonate mold with 740 nm periodic grooves was replicated on an Al foil using an underwater shockwave. Underwater detonation of a high explosive creates a shockwave with pressure ≥ 1 GPa that lasts for more than 100 ns, significantly longer than that for LSI. This provides a relief depth equal to 90% of the depth of the grooves on the mold. This mold filling efficiency is the best achieved by shock imprinting reported to date. In addition, underwater shockwaves can be used for imprinting over a large area in a single shot. Furthermore, the thickness of the Al foil can be increased in comparison to that for LSI. Using a simplified 1-D model of foil acceleration, we showed that increasing the foil thickness decreases the imprinting accuracy. This study paves new ways for large-area manufacturing of micro/nanopatterns on metals that would be especially beneficial for future applications in the fields of plasmonics and metasurfaces. Unlabelled Image • The detonation of an explosive charge creates an underwater shock wave. • The underwater shock wave replicated sub-micrometer relief of a mold onto foil. • The developed approach provides high imprinting accuracy. • The maximum foil thickness for nanoimprinting can be increased. [ABSTRACT FROM AUTHOR]