Katsumi Katoh

Effect of transition metal doping under reducing calcination atmosphere on photocatalytic property of TiO2 immobilized on SiO2 beads

TiO2 immobilized on SiO2 (TiO2/SiO2) have been prepared by sol-gel method and various ions of transition metals (Cr3+, Co2+ Ni2+, CU2+, and Zn2+) were doped on the photocatalyst using wet impregnation method under reducing calcination atmosphere. The photocatalytic activity of metal doped TiO2/SiO2 towards phenol degradation under black light irradiation were investigated and compared with undoped TiO2/SiO2. The results showed that the photoresponse of Cu2+ and Zn2+ doped TiO2/SiO2 were larger than undoped TiO2/SiO2, indicating that the photogenerated carriers were separated more efficiently in Cu2+ and Zn2+ doped TiO2/SiO2. The reactivity was in the order of Cu2+ > Zn2+ > Ni2+ > Cr3+ > Co2+. The different photoreactivity was ascribed to combine effect of the different ionic radii and photocorrison tendency of the dopants. The sample was also characterized by surface analytical methods such as X-ray diffraction, scanning electron micrograph/electron dispersive X-ray analyzer and UV-Vis absorption spectrum.

Observation of Shock Initiation Process in Gap Test

We have conducted the experiments for shock sensitivity of high energetic materials by gap test. The set up of gap test have been improved to observe the shock initiation phenomena in acceptor charge by high‐speed video. The length of gap material was varied to observe the reaction process under various situations. The luminescence at the surface of acceptor holder was used Go/Nogo decision. The distance from the gap end to the luminescence area increases with increasing in gap length. In the critical gap length in which the sympathetic detonation does not occur, the remarkable decomposition of acceptor charge was observed as gas expansion.

Effect of polymer addition amount and type on thermal decomposition behavior of spray-dried particles comprising ammonium nitrate, potassium nitrate, and polymer

Certain properties of ammonium nitrate (AN), such as high hygroscopicity and the thermal transformation of the crystal structure accompanied by volume changes, pose problems for industrial applications of AN. To solve these problems, we previously prepared AN-based particles by spray-drying. The particles contained potassium nitrate (PN) as a phase stabilizer and a polymer (e.g., PVA, CMCs, and Latex) to produce a moisture-resistant material. Herein, we investigate the thermal decomposition of spray-dried AN/PN/polymer particles by differential scanning calorimetry and Thermogravimetry–Differential thermal analysis. Comparison of the thermal decomposition of AN/PN/polymer materials with different amounts and types of polymers suggested that thermal decomposition at lower temperatures resulted from the reaction of AN with the molten polymer or decomposition products derived from the polymer. Therefore, it can be concluded that the thermal stability of the AN/PN/polymer was exclusively determined by the thermal properties of the polymer components.

NON-IDEAL DETONATION PROPERTIES OF AMMONIUM NITRATE AND ACTIVATED CARBON MIXTURES

To obtain a better understanding of detonation properties of ammonium nitrate (AN) and activated carbon (AC) mixtures, steel tube tests with several diameters were carried out for various compositions of powdered AN and AC mixtures and the influence of the charge diameter on the detonation velocity was investigated. The results showed that the detonation velocity increased with the increase of the charge diameter. The experimentally observed values were far below the theoretically predicted values made by the thermodynamic CHEETAH code and they showed so-called non-ideal detonation. The extrapolated detonation velocity of stoichiometric composition to the infinite diameter showed a good agreement with the theoretical value.

Diameter Effect on Detonation Velocity of Ammonium Nitrate and Activated Carbon Mixtures

To obtain a better understanding of detonation properties of ammonium nitrate (AN) and activated carbon (AC) mixtures, steel tube test with several diameters was carried out for various compositions of powdered AN and AC mixtures and the influence of the charge diameter on the detonation velocity was investigated. The results of test indicated that the detonation velocity increased with the increase of the charge diameter. The experimentally observed values were far below the theoretically predicted values made by the thermohydrodynamic CHEETAH code and they showed so-called non-ideal detonation. The extrapolated detonation velocity of stoichiometric composition to the infinite diameter showed a good agreement with the theoretical value.

Spontaneous Ignition Behavior of Nitrocellulose–Sulfuric Acid Mixtures

Nitrocellulose (NC) is known to undergo spontaneous ignition, and its thermal stability has been previously reported to decrease in the presence of sulfuric acid. In this study, we evaluated the decomposition and ignition behavior of NC in the presence of sulfuric acid using an accelerating rate calorimeter (ARC) and hand-built ignition testing equipment. The results of the ARC experiment indicated that the thermal stability of NC decreased when the amount of sulfuric acid was increased above 10-5 mol/g (NC). In addition, when NC (4 g) mixed with sulfuric acid (6.6 mol/L, 1 g) was isothermally stored at 75°C in a glass flask, the color of the reaction mixture changed from white to brown. After 83–127 min, NC spontaneously ignited and produced a loud explosion.

Development of Compact Blast Containment Vessel for 10 kg Explosive

The development study of blast containment vessels for anti-terrorism has been conducted. The goal of this study is to develop safe disposal vessel for 10 kg of explosives. Considering of the use at the airport or railroad stations, it needs to be more compact compared with the conventional explosion chamber. By introducing both the internal structure and attenuation technology in the vessel, sufficient blast proof ability to contain internal explosion is realized. The blast containment vessel can be used repeatedly by exchanging the internal structure. To realize these concepts, model experiments were carried out using high speed photography, strain and pressure measurements. By introducing these technologies, the vessel for the 1 kg of explosive materials has been made, and the experiments employing 1 kg C4 explosive have been conducted. Finally, the compact blast containment vessel for 10 kg explosives was made, and its blast proof ability was shown by the internal blast test.