Technological Features of the Liquid-Solid State of the Boundary Layer in the Processes of Bimetallic Products

The hydrodynamic and thermal state in the contact zone of the layers of a bimetallic product obtained by pouring liquid iron onto a solid steel billet, which changes in time and is responsible for the strength of the diffusion joint and the geometric parameters of the transition layer, has been investigated. Simplified analytical dependences, mathematical modeling data and experimental results of the liquid phase existence time in the contact zone based on research of the melt velocities during pouring and changes in the thermal field are presented. It is shown that simplified calculations data coincide in order and are close in values ​​to the calculations of mathematical modeling and experimental data, which makes it possible to use them for preliminary rough estimates by technologists and metallurgists.

Motion-induced energy shifts of a multilevel atom in a black-body radiation field

We investigate the influence of atomic uniform motion on radiative energy shifts of a multilevel atom when it interacts with black-body radiation. Our analysis reveals that the atomic energy shifts depend crucially on three factors: the temperature of black-body thermal radiation, atomic velocity, and atomic polarizability. In the low-temperature limit, the presence of atomic uniform motion always enhances the effect of the thermal field on the atomic energy shifts. However, in the high-temperature limit, the atomic uniform motion enhances the effect of the thermal field for an atom polarizable perpendicular to the atomic velocity but weakens it for an atom polarizable parallel to the atomic velocity. Our work indicates that the physical properties of atom–field coupling systems can in principle be regulated and controlled by the combined action of the thermal field and the atomic uniform motion.

Investigation of Deoxidation Process of MoO3 Using Environmental TEM

In situ environmental transmission electron microscope (ETEM) could provide intuitive and solid proof for the local structure and chemical evolution of materials under practical working conditions. In particular, coupled with atmosphere and thermal field, the behavior of nano catalysts could be directly observed during the catalytic reaction. Through the change of lattice structure, it can directly correlate the relationship between the structure, size and properties of materials in the nanoscale, and further directly and accurately, which is of great guiding value for the study of catalysis mechanism and the optimization of catalysts. As an outstanding catalytic material in the application of methane reforming, molybdenum oxide (MoO3)-based materials and its deoxidation process were studied by in situ ETEM method. The corresponding microstructures and components evolution were analyzed by diffraction, high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectrum (EELS) techniques. MoO3 had a good directional deoxidation process accompanied with the process of nanoparticles crushing and regrowth in hydrogen (H2) and thermal field. However, in the absence of H2, the samples would exhibit different structural evolution.

A multi-scale E-Jet 3D printing regulated by structured multi-physics field

Micro/nano scale structure as important functional part have been widely used in wearable flexible sensors, gas sensors, biological tissue engineering, microfluidic chips super capacitors and so on. Here a multi-scale electrohydrodynamic jet (E-Jet) 3D printing approach regulated by structured multi-physics fields was demonstrated to generate 800 nm scale 2D geometries and high aspect ratio 3D structures. The simulation model of jetting process under resultant effect of top fluid field, middle electric field and bottom thermal field was established. And the physical mechanism and scale law of jet formation were studied. The effects of thermal field temperature, applied voltage and flow rate on the jet behaviors were studied; and the range of process parameters of stable jet was obtained. The regulation of printing parameters was used to manufacture the high resolution gradient graphics and the high aspect ratio structure with tight interlayer bonding. The structural features could be flexibly adjusted by reasonably matching the process parameters. Finally, PCL/PVP composite scaffolds with cell-scale fiber and ordered fiber spacing were printed. The proposed E-Jet printing method provides an alternative approach for the application of biopolymer materials in tissue engineering.

Controls of the lithospheric thermal field of an ocean-continent subduction zone: the southern Central Andes

In an ocean-continent subduction zone, the assessment of the lithospheric thermal state is essential to determine the controls of the deformation within the upper plate and the dip angle of the subducting lithosphere. In this study, we evaluate the degree of influence of both the configuration of the upper plate and variations of the subduction angle on the lithospheric thermal field of the southern Central Andes (29°–39°S). Here, the subduction angle increases from subhorizontal (5°) north of 33°S, to steep (~30°) in the south. We derived the 3D temperature and heat flow distribution of the lithosphere in the southern Central Andes considering conversion of S wave tomography to temperatures together with steady-state conductive modeling. We found that the orogen is overall warmer than the forearc and the foreland, and that the lithosphere of the northern part of the foreland appears colder than its southern counterpart. Sedimentary blanketing and the thickness of the radiogenic crust exert the main control on the shallow thermal field (< 50 km depth). Specific conditions are present where the oceanic slab is relatively shallow (< 85 km depth) and the radiogenic crust is thin, This configuration results in relatively colder temperatures compared to regions where the radiogenic crust is thick and the slab is steep. At depths >50 km, the temperatures of the overriding plate are mainly controlled by the mantle heat input and the subduction angle. The thermal field of the upper plate likely preserves the flat subduction angle and influences the spatial distribution of shortening.