Papers by Keyword: Water

Abstract: Underwater laser machining process has been employed as an alternative process to ablate materials with minimum thermal damage. Though many studies provide comprehensive investigations to enable the understanding of laser-water-material interactions during the laser ablation process in water, the effect of water temperature on the ablation performance has not been revealed yet. To cope with this challenge, this paper presents the roles of water temperature on cut dimensions in the underwater laser micromachining of titanium alloy (Ti-6Al-4V). The effects of laser power, traverse speed and number of laser passes were also examined in this study, where groove width and depth were measured and analyzed. The experimental results showed that a deep cut can be produced by using slow traverse speed with multiple-pass technique. However, using too high laser power can cause a shallow cut due to the large formation of recast in the laser-ablated area. According to the findings of this study, the laser energy density of about 750 J/mm² can provide the deepest cut among the other conditions examined in this study.

Abstract: We report synthesis of nanosized oxide materials using a novel water assisted solid state reaction (WASSR) method. This novel soft chemical synthesis method is very simple and can synthesize nanoparticle materials just by storing or mixing raw materials added a small amount (typically 10wt%) of water in a reactor at low temperature below 373 K. Combinations of raw materials have a significant influence on the reaction rate.

Abstract: A subsurface magazine has an explosive storage chamber, a horizontal passageway, and a vertical shaft for vent. It was proposed and legislated in Japan. The authors found that small amount of water on the floor of its storage chamber mitigated the blast pressure remarkably. The mechanism of the mitigation has been studied, however, it is not still well understood. In this study, the explosion in a transparent, square cross section, and straight tube was carried out to examine the mechanism of blast-wave mitigation by water. The arrangement and amount of water in the tube were varied for five ways. The dependence of mitigation effect on the arrangement and amount of water was evaluated by measuring the blast pressures in the tube and outside the tube. The results of this study concluded that the mitigation of blast wave by water is mainly due to the interaction between the explosion and the water very near the explosion point. On the contrary, the water at other part of the tube was found to strengthen the blast pressure.

Abstract: This paper investigates explosions in a straight square tube in order to understand the mitigation effect of water on blast waves that emerge outside. Numerical simulations are used to assess the effect of water that is put inside the tube. The water reduces the peak overpressure outside, which agrees well with the experimental data. The increases in the kinetic and internal energies of the water are estimated, and the internal energy transfer at the air/water interface is shown to be an important factor in mitigating the blast wave in the present numerical method.

Abstract: We report a novel soft chemical synthesis method, water assisted solid state reaction (WASSR) method. This method is very simple and can synthesize many ceramic materials just by storing or mixing raw materials added a small amount of water in a reactor at low temperature below 373 K. For example, well-crystalline SrMoO₄ was obtained using the WASSR method.

Abstract: In order to maintain the volume of oil and gas supplies, the number of oil and gas wells increases every year, drilling platforms are built, which proportionally increases the amount of sludge and drilling waste mud, which must be recycled. The research gives light to the danger of introducing chemical substances into various natural environments from industrial and anthropogenic sources on an example of drill cuttings from oil fields of Tomsk region.

Abstract: Water plays a crucial role in the growth and development of species on Earth. Changes in the physicochemical properties of water have a large effect on the human activities. Researchers have researched and evaluated effects of electric current frequency on the physicochemical properties of distilled water samples. The effect of electric fields on the physicochemical properties of water allows it to identify the optimal treatment regimes that promote the intensification of various processes taking place in an aqueous medium or in the presence of water.

Abstract: Growth of gallium oxide thin film was realized with MOCVD on (0001) sapphire substrate. Structural and compositional properties of thin film were studied employing trimethylgallium and water as precursors, carrier gases were H₂ and N₂. Obtained film is polycrystalline and predominantly consisted of (201) oriented β-Ga₂O₃. Sample exhibited blue luminescence which is attributed to oxygen vacancies. H₂ gas proved to have beneficial effect on film quality and overall growth process.

Abstract: The problems of hydrogen energetic as well as a method of high pure hydrogen obtaining are presented in the paper. It was suggested to use the reaction of aluminium nanopowder with water, as the reaction proceeds with high rate even at ambient conditions (the rate of hydrogen emission reached 18 ml/(s∙g)) and high degree of conversion (up to 100 %). The unreasonableness of the replacement of aluminium nanopowder to coarse-grained powder in this reaction due to the low efficiency is shown in the article. As a solution for pure hydrogen obtaining, a phenomenon of self-heating of aluminum nanoparticles and the resulting hydrogen, as well as the effect of its high-temperature diffusion through the membrane of ultrahigh molecular weight polyethylene were used.

Abstract: Laser ablation under a flowing water layer can reduce thermal damage in work material and also provide a better machining performance than processing in ambient air. However, there is still a lack of insight into a more complicated process like laser milling operation in water. Besides the laser parameters, the roles of water flow direction on the cut geometries need to be elucidated to realize the viability and reliability of the laser milling process in water. This study is for the first time to reveal the effects of water flow direction on the cavity dimensions and cut surface roughness in the laser milling process performed under a flowing water layer. Titanium alloy was used as a work sample in this study. The experimental results indicated that the laser beam should travel in the same direction of water flow to provide a uniform cavity depth and smooth milled surface.