Results 1 - 10 of 8022
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[en] Surface enhancement to prevent wear, self welding, thermal shock stress and irradiation attack is obtained by applying spray coatings performed by the detonation gun process. The equipment and the process are described and density hardness, porosity, microstructure and bond strength of the coatings are examined
[en] We present results for the transfer characteristics of carbon nanotube thin-film transistors (CNT-TFTs) that utilize single-walled carbon nanotube thin-films prepared by direct spray-coating on the substrate. By varying the number of spray-coatings (Nsp) and the concentration of nanotubes in solution (CNT), it was possible to control the conductivity of the spray-coated nanotube thin-film from 129 to 0.1 kΩ/□. Also, by introducing stripes into the channel of the CNT-TFT, and thereby reducing the number of metallic percolation paths between source and drain, it was possible to enhance the on/off current ratio 1000-fold, from 10 to 104, demonstrating that it may be possible to utilize spray-coating as a method to fabricate CNT-TFTs for large area switching array applications. (paper)
[en] Within the framework of the ERCOSAM-SAMARA project, co-funded by the European Union and the Russian State Atomic Energy Corporation, planning and pre-test calculations are performed to examine sensitivity parameters that can affect the break-up (erosion) of a helium (substitute for hydrogen) layer by mitigation devices (i.e., cooler, spray, or Passive Autocatalytic Recombiner - PAR). This paper reports the GOTHIC analysis results for the spray tests to be performed in the PANDA facility. The effects of spray flow rate, temperature and injection height on depressurization, erosion of helium cloud and gas transport behavior are studied. This analysis is valuable because only a limited number of conditions will be examined in the planned experiments. The study provides a useful understanding of the interaction of spray with a stratified atmosphere. (author)
[en] The aim of present work was principally focus upon development of Mo composite coating using HVOF thermal spray coating process and to enhance residual stresses using Taguchi approach. The process parameter used in Taguchi experiment are Temperature, load and frequency. ANOVA method was used to examine and analyze the process parameters significance of Mo composite coating. The HRXRD and FESEM attached EDS were used to confirm surface morphology and presence of Mo based composite coating on steel substrate. Experimental results also concluded that for percent (%) change in residual stress, temperature (64.19%) has maximum % contribution followed by frequency (21.82%) and load (6.31%). (paper)
[en] Splashing of splat particles is one of the most important phenomena in industrial processes such as thermal spray coating. The data relative to the degree of splashing of splats sprayed with a normal angle are commonly characterized by the Weibull distribution function. In this present study, an effort has been made to show that the Burr distribution is better than the Weibull distribution for presenting the distribution of the degree of splashing. For this purpose, the Burr Type XII distribution and Weibull distribution are compared using different criteria. Furthermore, because of the great importance of statistical prediction of censored data in reducing costs and improving quality of the coating process, we consider different predictors of this data based on a progressively censored sample. For computing the prediction values we obtain the maximum likelihood estimates using the Expectation-Maximization (EM) algorithm. An important implication of the present study is that the Burr Type XII distribution more appropriately described the degree of splashing data. Therefore, the Burr Type XII can be used as an alternative distribution that adequately describes the splashing data and thereby predicts the censored data.
[en] Purpose: To attain a highly efficient spray cooling by injecting cooling water of a high unsaturation degree into the outer periphery of a reactor core to moderate the flow-restriction caused by the upgoing steam streams in the outer periphery. Constitution: Spray nozzles of spray headers are provided near the outer periphery of the reactor core, and water spray is conducted upon loss of coolant accidents from the spray headers to the entire reactor core and from the spray header with the nozzle to the fuel assembly in the outer periphery of the core. While the spray water from the spray nozzle loses its unsaturation degree in contaction and admixture with two-phase mixture consisting of steam and saturated water accumulated in the upper plenum by the flow-restriction phenomena, the spray water from the lead nozzle is difficult to mix with the two-phase mixture in the upper plenum and the extent of decrease in the unsaturation degree due to the heat exchange is low. Then, this is injected as cooling water with a high unsaturation degree into the fuel assemblies to enable highly efficient spray cooling. (Moriyama, K.)
[en] Object: To improve the spray cooling function of an emergency core cooling system by providing holes in the channel wall of a fuel assembly used for the boiling water type reactor in the neighborhood of the lower end of the channel wall. Structure: The lower end of a channel wall enclosing the assembly of fuel rods in a fuel rod assembly used for a boiling water type reactor is provided with holes. At the time of emergency core cooling, spray water collected in the flow path of the fuel assembly through the afore-mentioned holes is effectively led into the interior of the fuel assembly. In this way, while cooling the fuel rods in a high temperature state, an increase in the lower plenum water level is accelerated and spray cooling is further reinforced. (Moriyama, K.)
[en] Thermal spray coatings, often composed of heterogeneous, multiphase microstructures, may, consequently, exhibit complex fracture behavior. For such coating structures, conventional mechanical evaluation methods fail to isolate the contribution of microstructural features to the overall fracture behavior. For this reason, this study employed focused ion beam machined (FIB) microcantilever beams and FIB sectioning methods to study the fracture mechanisms important at the scale of the heterogeneous Cr3C2-NiCr thermal spray coating. We found three fracture modes, namely, intergranular matrix fracture, matrix/carbide interfacial fracture, and carbide cleavage. By comparison, microindentation-induced cracks, the frequency of crack deflection around carbides is significantly more prevalent at this much larger crack dimension. This mechanistic variation provides some insight into the specific role and limitations of the microcantilever beam technique for fracture characterization of composite microstructures.
[en] Purpose: To enable a large quantity of cooling water to be injected simultaneously into fuel channels upon actuation of emergency core cooling device in BWR type reactors. Constitution: A line comprising a gas in-take port and a blower for feeding gas to the upper plenum in the pressure vessel of a nuclear reactor is provided for introducing gaseous nitrogen in the containment shell to the upper plenum of the pressure vessel. The line is actuated upon operation of the emergency core cooling device. Then, the spray water from the spray nozzle of the emergency core cooling device is uniformly sprayed to each of the channels with the spray diverging angle not being restricted. (Ikeda, J.)