Search results for "engineering.material"
showing 10 items of 2352 documents
Influence of growth parameters and melt convection on the solid-liquid interface during RF-floating zone crystal growth of intermetallic compounds
2001
Abstract The influence of growth parameters and melt convection on the solid–liquid interface of the intermetallic compound Ni3Si grown by the RF-floating zone technique was investigated experimentally as well as numerically. Numerical simulations showed that the heat transfer is strongly influenced by the electromagnetically driven and Marangoni convections whereas both the buoyancy and feed rotation have a negligible effect. It was found experimentally that the inductor design, the rod diameter and the length of the molten zone influence the solid–liquid interface shape significantly. The electromagnetically driven convection increases dramatically with increasing zone length due to the r…
Numerical and Experimental Analysis of Convection Transfer During Melting by a Mono-Pulsed Laser
2010
This paper presents a comparison between simulation and experimental results of the melting process of metallic material by a pulsed laser source Nd-YAG. Variations of the thermophysical properties were considered. Furthermore, the model included the effects of the surface-tension gradient on the fluid surface and the buoyancy force. The keyhole effect induced strong surface deformations and often formed cavities, which arre undesirable in the surface treatment process. An experimental study of the surface profile of the melted zones was also conducted to seek a relationship between the so-called keyhole effect and the laser triangulation measurements. The predicted Laser Melted Zone (LMZ) …
The Effect of Intense Air Drying on Material Distribution and Quality in Coated Papers
2003
Abstract The aim of this study was to find out what will happen to paper coating quality and material gradients if coating is dried in one air dryer at a high convection rate (150 kg/m2h). Different printing papers were coated, calendered and printed with pilot machines. The binder and pigment gradients of the coated, and also printed, samples were analyzed with LIPS (Laser Induced Plasma Spectrometry). It was found that drying affects the migration of starch, but not latex. Total air drying can be used to dry printing papers, if air temperature, velocity and moisture content can be separately controlled. The control of web temperature is more important for paper quality formation in a coat…
Modeling of Melt Flow and Heat Transfer in Stationary Gas Tungsten Arc Welding with Vertical and Tilted Torches
2021
A 3D numerical simulation was conducted to study the transient development of temperature distribution in stationary gas tungsten arc welding with filler wire. Heat transfer to the filler wire and the workpiece was investigated with vertical (90°) and titled (70°) torches. Heat flux, current flux, and gas drag force were calculated from the steady-state simulation of the arc. The temperature in the filler wire was determined at three different time intervals: 0.12 s, 0.24 s, and 0.36 s. The filler wire was assumed not to deform during this short time, and was therefore simulated as solid. The temperature in the workpiece was calculated at the same intervals using heat flux, current flux, ga…
Influence on the macrosegregation of binary metallic alloys by thermoelectromagnetic convection and electromagnetic stirring combination
2014
International audience; Influence of a slowly rotating 0.5 T transverse magnetic field on the directionally solidified metallic alloy has been experimentally studied in this work. Main idea is to study an influence on the melt flow and material structure caused by the simultaneous electromagnetic stirring and thermoelectromagnetic convection with comparable magnitudes. Electromagnetic stirring and thermoelectromagnetic convection intensities have been estimated analytically to find optimal experimental parameters. It is experimentally demonstrated that with such an interaction it is possible to modify component macrosegregation of Sn-10 wt% Pb alloy. Helical macrosegregation within cylindri…
Impacts of Varying Concentrations of Cloud Condensation Nuclei on Deep Convective Cloud Updrafts—A Multimodel Assessment
2021
AbstractThis study presents results from a model intercomparison project, focusing on the range of responses in deep convective cloud updrafts to varying cloud condensation nuclei (CCN) concentrations among seven state-of-the-art cloud-resolving models. Simulations of scattered convective clouds near Houston, Texas, are conducted, after being initialized with both relatively low and high CCN concentrations. Deep convective updrafts are identified, and trends in the updraft intensity and frequency are assessed. The factors contributing to the vertical velocity tendencies are examined to identify the physical processes associated with the CCN-induced updraft changes. The models show several c…
Phase and structural transformations in annealed copper coatings in relation to oxide whisker growth
2015
Abstract We describe structural and phase transformation in copper coatings made of microparticles during heating and annealing in air in the temperature range up to 400 °C. Such thermal treatment is accompanied by intensive CuO nanowhisker growth on the coating surface and the formation of the layered oxide phases (Cu 2 O and CuO) in the coating interior. X-ray diffraction and focused ion beam (FIB) are employed to characterize the multilayer structure of annealed copper coatings. Formation of volumetric defects such as voids and cracks in the coating is demonstrated.
Synthesis and Stability Region of Stoichiometric Nanocrystalline Vanadium−Iron Spinel Powders
2000
Vanadium-iron spinels with nanometric sizes have been synthesized by a soft chemistry route. This way of elaboration consists of a coprecipitation followed by thermal treatments at low temperatures. The last thermal annealing is performed under a reducing atmosphere in order to obtain the exact oxygen stoichiometry (four oxygen atoms for three metal atoms in AB 2 O 4 ). Because of the low temperatures used, very low oxygen partial pressures (between 10 -20 and 10 -30 Pa) have to be applied. For this purpose, a reducing setup has been used. It consists of H 2 /N 2 /H 2 O gas mixtures, creating a reducing atmosphere with low oxygen partial pressure. This atmosphere can be applied to a sample …
The influence of hydrogen on the electrochemical properties of selected types of stainless steel=Wpływ wodoru na właściwości elektrochemiczne wybrany…
2013
Abstract The paper presents the results of the influence of electrolytic hydrogenation on the change of electrochemical properties of selected stainless steels and their susceptibility to the formation of galvanic hydrogen. It has been shown that the electrolytic hydrogenation of steel X5CrNi18-10 and X6Cr17 in the state of delivery, not only changes their corrosion resistance, but also contributes to the formation of galvanic hydrogen cells.