Optimization of Mechanically Assembled Van Der Waals Heterostructure Based On Solution Immersion and Hot Plate Heating

Layers of two-dimensional material are bonded together by van der Waals force, as a result, there is no need to take into consideration of the lattice mismatch in the formation of heterojunction, which is endowed with the characteristics of simple stacking in method, free of limitation to the type of materials and diverse changes. However, although the Van Der Waals heterojunction is relatively easy to stack, it is still difficult to generate inter-layer coupling between the thin crystal layers that form the Van Der Waals heterojunction. In most cases, the stacked heterojunction is simply stacked together without any new effects. Therefore, the realization of heterojunction coupling is a difficult problem to be considered in the process of preparing Van Der Waals heterojunction. In this paper, a method based on solution immersion and hot plate heating is proposed to optimize the mechanical stacking of Van Der Waals heterojunctions. It is found that the heterojunctions prepared by normal mechanical stacking method are usually uncoupled before treatment, but they can be stably coupled after treatment. Our method, simple, fast with low-cost, has been repeatedly verified to have a high success rate of coupling, which is suitable for most experimental groups to use and reproduce.

INTENSIFICATION AND STUDY OF HEAT TRANSFER AND FRICTION IN THE PLATE HEATING SURFACES OF THE KMS-2 AIR HEATER WITH A PRESSURE GRADIENT

A numerical study of heat transfer and friction in the heat exchanger channels in the presence of a variable pressure gradient is performed. The research was carried out in software complexes (Code_Saturne, Salome). The results of the validation of the research method are presented and they showed that the deviation of the numerical simulation results from the calculation data according to the known criterion equations is within the error of generalization of the experimental data by the criterion equations. According to the results of studies at Red=3000, Red=4177, Red=6000, it was found that the average value of the heat transfer coeffi cient of the channel of variable cross-section is up to 20 % higher than for the channel at dp/dx0. At the same time, the thermal-hydraulic effi ciency of the alternating channel (L=117 mm, l=58.5 mm, n=2) in the initial section at x =0...0.08 is lower than in the channel with dp/dx>0 by 26.7 %, and at x =0.08...1 it is higher by 5 ... 15 %, at dp/dx

Effect of Substrate Plate Heating on the Microstructure and Properties of Selective Laser Melted Al-20Si-5Fe-3Cu-1Mg Alloy

The Al-20Si-5Fe-3Cu-1Mg alloy was fabricated using selective laser melting (SLM). The microstructure and properties of the as-prepared SLM, post-treated SLM, and SLM with substrate plate heating are studied. The as-prepared SLM sample shows a non-uniform microstructure with four different phases: fcc-αAl, eutectic Al-Si, Al2MgSi, and δ-Al4FeSi2. With thermal treatment, the phases become coarser and the δ-Al4FeSi2 phase transforms partially to β-Al5FeSi. The sample produced with SLM substrate plate heating shows a relatively uniform microstructure without a distinct difference between hatch overlaps and track cores. Room temperature compression test results show that an as-prepared SLM sample reaches a maximum strength (862 MPa) compared to the heat-treated (524 MPa) and substrate plate heated samples (474 MPa) due to the presence of fine microstructure and the internal stresses. The reduction in strength of the sample produced with substrate plate heating is due to the coarsening of the microstructure, but the plastic deformation shows an improvement (20%). The present observations suggest that substrate plate heating can be effectively employed not only to minimize the internal stresses (by impacting the cooling rate of the process) but can also be used to modulate the mechanical properties in a controlled fashion.

Metallic plate heating by a flat burner: Experiments and CFD simulations

Metal plate heating by new microflare burner has been studied experimentally and by CFD simulations, additionally, concentrations of NOx were measured to compare conventional and microflare burners. In addition, the article provides a numerical simulation of the combustion of a microflame burner. It has been demonstrated that microflare burners are more efficient and allows more uniform heating of metal plates. The comparison of NOx concentrations of conventional and microflare burners indicate better performance of the latter.

Fabrication of Stretchable Transparent Electrode by Utilizing Self-Induced Vacuum Force

The key challenge in fabricating a stretchable transparent electrode is the effective transfer of an electric conductor to a stretchable substrate. To this end, we used vacuum force to fully permeate the elastomer substrate into the electric conductor. The vacuum force was self-induced from the evaporation of the solvent in the electric conductor. Hence, a solvent, having a high evaporation rate, is postulated to exhibit superior fabrication quality. To demonstrate this, three different solvents were tested for preparation of the conductor slurry. In the test, the high-vapor-pressure solvents resulted in the superior quality of the fabricated stretchable electrode. Furthermore, the heating direction was changed during thermal curing to maximize the self-induced vacuum force. The plate-heating curing exhibited better transferring efficiency of the electric conductor because the evaporation of the solvent in the conductor slurry was accelerated faster than that of the thermal curing of the elastomer substrate. Besides the achieved high quality of the electrode, the fabrication cost can be drastically reduced because the extra process required to dry the electric conductor is omitted by simultaneous curing of the electric conductor and the stretchable elastomer substrate.

Heat Transfer with Absorption in Anisotropic Thermal Protection of High-Temperature Products

The purpose of the research was to study the non-stationary heat transfer in anisotropic thermal protection under the action of unsteady heat flows distributed along the body, when there are thermal energy sinks inside the body, the energy being proportional to temperature, due to endothermic physical and chemical transformations. Thermal protection is made of anisotropic material, such as phenol-formaldehyde fiberglass, asboplastics, carbon-carbon plastics, etc. A new analytical solution has been obtained for the problem of plate heating under the action of unsteady heat flows distributed along the body. Using this solution, we studied the temperature fields when the components and orientation angles of the main axes of the thermal conductivity tensors of anisotropic heat-shielding materials were changed. Findings of research show that with increasing time, the temperature field inside the plate is localized and does not extend further than the limiting isotherm.

An Atom-economic Efficient Synthesis of 1-Amidoalkyl-2-naphthols Mediated By Hexachlorocyclotriphosphazene (HCCP) as a Novel Catalyst

A multicomponent one-pot atom-economic reaction is performed for an efficient synthesis of 1-amidoalkyl-2-naphthol from aromatic aldehydes, β-naphthol and amide/urea promoted by hexachlorocyclotriphosphazene (HCCP). Various techniques such as stirring, microwave irradiation and thermal technique (hot plate and oil bath) were used in different solvents for the synthesis of 1- amidoalkyl-2-naphthol derivatives with moderate to excellent yield. Among the four methods, microwave irradiation and oil bath heating provide high yield as compared to the hot plate heating and stirring method. The low yield may be due to the formation of undesired side-products due to non-uniform heating.