scholarly journals Formation of a stable defects structure in silicon noise diodes

2021 ◽  
Vol 66 (2) ◽  
pp. 145-153
Author(s):  
V. V. Emelyanov ◽  
V. A. Emelyanov ◽  
V. V. Baranov ◽  
V. V. Busliuk
Keyword(s):  
Dislocation Structure ◽  
Experimental Studies ◽  
Melting Process ◽  
Melting Zone ◽  
Laser Spot ◽  
Dislocation Generation ◽  
Defective Structure ◽  
Plate Area ◽  
Secondary Ion ◽  
Stable Dislocation

vThe possibilities and methods of creating a stable defective structure, including dislocation structure near the zones of p–n-transitions of silicon diodes of noise generators on plates with crystallographic orientations (111) and (001) have been investigated. The effective distribution control of uncontrolled impurities in monocrystalline silicon is achieved by forming a stable dislocation structure in its volume. In order to obtain the reproducible characteristics of noise generator diodes, it is necessary that the dislocation density be homogeneous throughout the plate area. Since the density of dislocations is slightly lower at the edge of the dislocation trail than in the middle, this means that the dislocation traces formed by the adjacent melting zones with the help of a laser beam should overlap. On the basis of experimental studies, it has been established that the necessary degree of uniformity of the density of defects generated is achieved by compliance with the condition of a = (1.5–5.0)d, where a is a step, d is a width of the laser spot on the wafer. The melting process was carried out in a nitrogen environment using a laser hettering unit. The real width of the melting zone turns out to be slightly larger than the diameter of the laser spot due to the thermal conductivity of the silicon and is about 10 μm. Increased dislocation generation on the Si3N4 inclusions, as opposed to dislocations on the Si–SiO2 border, leads to an additional expansion of the dislocation track at the work surface of the plate of noise diodes. The presence of the stable dislocation structure, as well as the presence of impurities and secondary metal atoms in the noise diodes ND 103L structure are confirmed by the secondary ion mass spectroscopy (SIMS) method. The results of the study have been tested at Corporation “INTEGRAL” (Belarus) and can be used in the manufacture of silicon noise diodes.

Effect of Refining Slag on the Inclusions of Hard Wire Steel during Melting Process

2011 ◽  
Vol 217-218 ◽  
pp. 1174-1179
Author(s):  
Yang Li ◽  
Zhou Hua Jiang ◽  
Shi You Yin ◽  
Ying Zhuang ◽  
Ming Li
Keyword(s):  
Ternary Phase Diagram ◽  
Melting Process ◽  
Melting Zone ◽  
Refining Slag ◽  
Total Oxygen ◽  
Deformation Ability ◽  
Inclusion Shape ◽  
Wire Steel ◽  
Al2o3 Inclusion ◽  
Inclusions In Steel

The effect of the refining slag composition on the total oxygen content and inclusions in steel was investigated in 100 t UHP Electric Furnace – LF – Billet CC process. The test steel was 77B hard wire steel and Si-Mn alloy was used as the deoxidizer. Three types slag were used in the industrial tests, which including CaO-CaF2, CaO-CaF2 adding CaC and CaO-Al2O3 refining slag. The results shown that the lowest total oxygen contents of rolled bar can be gained using the CaO-CaF2 refining slag adding CaC, which is 0.0036%, while the total oxygen contents of rolled bar using CaO-Al2O3 refining slag is higher a little than the heats using CaO-CaF2 refining slag. The CaO-SiO2 and CaO-Al2O3-SiO2 compound inclusions with the size of about 5 μm are the main inclusions in the heats refining by the CaO-CaF2 refining slag in the rolled bar, but the pure, indeformable Al2O3 inclusion can also be found with the size of about 10 μm. The CaO-Al2O3-SiO2 and Al2O3-SiO2-MnO compound inclusions are the main inclusions in the heats refining by the CaO-CaF2-CaC refining slag, but most of the inclusion shape is irregular with bigger size of about 10 μm. Similar with the heat using CaO-CaF2 refining slag, the pure Al2O3 inclusion with edge angle can be found in the rolled bar. The inclusions in the rolled bar treated by CaO-Al2O3 refining slag are CaO-Al2O3-SiO2 compound inclusions, most of which are nearly globular shape with the relative small size of about 5 μm. All of the inclusions in rolled bar lie on the low melting zone in the CaO-Al2O3-SiO2 ternary phase diagram in the heats using CaO-Al2O3 refining slag. The similar condition appeared on the most of the inclusions in the heats using CaO-CaF2 and CaO-CaF2 refining slag adding CaC, while part of which are lied on the high melting zone. Therefore, considering of the plastic deformation ability, the CaO-Al2O3 refining slag is the best slag for the melting process of hard wire steel.

Theoretical and experimental studies of the dislocation structure at the NiAl–Cr(Mo) interfaces

2000 ◽  
Vol 44 (3-4) ◽  
pp. 186-191 ◽  
Author(s):  
Y.X Chen ◽  
C.Y Cui ◽  
L.L He ◽  
J.T Guo ◽  
D.X Li
Keyword(s):  
Dislocation Structure ◽  
Experimental Studies

scholarly journals Features of intensive evaporation of liquid-metal steel drops heated in a high-frequency inductor

2021 ◽  
Vol 2088 (1) ◽  
pp. 012051
Author(s):  
D A Vinogradov ◽  
V V Glazkov ◽  
Yu P Ivochkin ◽  
K G Kubrikov ◽  
I O Teplyakov ◽  
...  
Keyword(s):  
Vortex Motion ◽  
Experimental Studies ◽  
Melting Process ◽  
Induction Melting ◽  
Primary Droplet ◽  
Qualitative Level ◽  
Explosive Fragmentation ◽  
Surrounding Space ◽  
Secondary Droplets ◽  
The Stability

Abstract The paper presents the results of experimental studies of the processes of intense melting in air of samples (solid balls) made of metals, primarily various steels. It is shown that the heating of some steels is accompanied by intense sparking - the ejection of small secondary droplets (sparks) from the primary droplet heated up to 2500 K into the surrounding space. A possible mechanism of this process is proposed and described at a qualitative level. Possible reasons for the explosive fragmentation of secondary droplets are indicated and experimentally confirmed. The vibration process of molten samples shell, caused by the vortex motion and evaporation of the melt inside the droplet, is described. The influence of spark formation on the stability of the induction melting process is demonstrated.

Non-Isothermal Simulation of Melting Process in Twin Screw Extruder Based on Two Typical Screw Configurations

2011 ◽  
Vol 130-134 ◽  
pp. 2273-2279
Author(s):  
Chang Liang ◽  
Bing Luo ◽  
Kui Sheng Wang
Keyword(s):  
Liquid Fraction ◽  
Melting Process ◽  
Melting Zone ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Twin Screw Extruders ◽  
Twin Screw ◽  
Higher Temperature ◽  
Study Heat Transfer ◽  
Screw Extruders

In this study, heat transfer and melting process in a co-rotating twin screw extruder are studied based on two typical screw configurations, screw element and kneading blocks staggered 45°. In order to estimate the melting ability of two configurations quantitatively, FEM software, FLUENT is adopted to simulate the cases. It could be concluded that kneading blocks have higher temperature rise and more liquid fraction than screw element, and it takes less time and less distance for kneading blocks to finish melting. Simulation results also show that kneading blocks have more viscous dissipation than screw element. Therefore, we can come to the conclusion that the kneading blocks are more suitable for the melting zone of co-rotating twin screw extruders.

scholarly journals Influence of Low Energy Density Laser Re-Melting on the Properties of Cold Sprayed FeCoCrMoBCY Amorphous Alloy Coatings

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 695
Author(s):  
Chao Han ◽  
Li Ma ◽  
Xudong Sui ◽  
Bojiang Ma ◽  
Guosheng Huang
Keyword(s):  
Energy Density ◽  
Corrosion Rate ◽  
Galvanic Corrosion ◽  
Salt Spray ◽  
Cold Spraying ◽  
Melting Process ◽  
Melting Zone ◽  
Low Energy ◽  
High Porosity ◽  
Melting Method

Fe-based amorphous alloys (FAA) have excellent anti-corrosion and anti-abrasive comprehensive performances. However, sprayed thin FAA coatings with high porosity cannot provide efficient protection, or even accelerate the corrosion rate of the substrate due to galvanic corrosion. Laser re-melting densifying is usually used to improve the anti-corrosion performance of sprayed coatings. There are two disadvantages of the common laser re-melting method, including crystallization and residual stress. In the present paper, a low density energy laser re-melting method was used to improve the performance of cold spraying (CS) FeCoCrMoBCY FAA coating on 40Cr substrate. The results show that the CS FAA coatings were crystallized partially during the melting process. The hardness of the coating is improved at the melting zone after laser re-melting, which improves the anti-abrasive performance. Potentiodynamic test results show that laser re-melting can decrease the corrosion rate, but the salt spray test indicates that low energy density re-melting cannot eliminate penetrated diffusion passage. Further optimization should be conducted to improve the anticorrosion performance for this method.

Transport phenomena and evolution mechanism of the melt pool during a laser based metal melting process

2021 ◽  
pp. 1-36
Author(s):  
Qingfei Bian ◽  
Ke Tian ◽  
Kong Ling ◽  
Yitung Chen ◽  
Min Zeng ◽  
...  
Keyword(s):  
Numerical Study ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Melting Process ◽  
Numerical Results ◽  
Interface Morphology ◽  
Momentum Exchange ◽  
Interface Capturing ◽  
Melt Pool ◽  
Metal Melting

Abstract This article presents a fully three-dimensional numerical study on the process of melt pool evolution. In order to overcome the simplifications used in many existing studies, an enthalpy method is developed for the phase change, and an accurate interface capturing method, i.e., the coupled volume-of-fluid and level set (VOSET) method, is employed to track the moving gas-liquid interface. Meanwhile, corresponding experimental studies are carried out for the purpose of validation. The obtained numerical results show the formed interface morphology during the process of melt pool with its typical sizes and are quantitatively consistent with those data measured in experiments. Based on the numerical results, the thermodynamic phenomena, induced by the interaction between heat and momentum exchange, occurring in the formation of melt pool are presented and discussed. Mechanisms of the melt pool evolution revealed in the present study provide a useful guidance for better controlling the process of additive manufacturing.

The Dislocation Structure and Deformation Mechanism of Tib2/Nial Composites

1990 ◽  
Vol 213 ◽  
Author(s):  
L. Wang ◽  
R.J. Arsenault
Keyword(s):  
Grain Size ◽  
Dislocation Density ◽  
Screw Dislocation ◽  
Dislocation Structure ◽  
Deformation Mechanism ◽  
Volume Fraction ◽  
Dislocation Generation ◽  
Screw Dislocations ◽  
Size Refinement ◽  
Dislocation Annihilation

ABSTRACTDislocation structures in 0, 10, and 20 V% TiB2/NiAl composites have been thoroughly investigated with a 1 MeV HVEM after compression testing at 760–1000° C. Samples with 0 and 10 V% TiBl2/NiAl additions have almost identical dislocation structures which can be described as a<100> screw dislocations with extensive jogs and superjoqs. Prismatically punched dislocations were observed in all of the deformed composites and deformed samples of 20 V% TiB2/NiAl had extensive dislocation generation around the particles. Dislocation density, grain size, and the tendency for dislocation reactions or networks forming during deformation decrease as the volume fraction of TiB2 increases. Also, since a predominance of screw dislocation was observed, the rate controlling process is not likely to be dislocation annihilation or climb, but dislocation generation. The grain size refinement could play an important role in the strengthening of the composites.

scholarly journals MODELING OF HEATING AND MELTING PROCESSES OF HYDROCARBON MIXTURES WITH FORCED REMOVAL OF THE MELT

2021 ◽  
Vol 43 (1) ◽  
pp. 89-96
Author(s):  
O.M. Obodovych ◽  
G.К. Ivanitsky ◽  
O.E. Stepanova
Keyword(s):  
Mathematical Modeling ◽  
Vessel Wall ◽  
Experimental Studies ◽  
Melting Process ◽  
Hydrocarbon Mixture ◽  
Cylindrical Tank ◽  
Melt Flow ◽  
Thermal Front ◽  
Hydrocarbon Mixtures ◽  
Annular Gap

Analysis of the work, which considered the mathematical modeling of the melting process in various industries, currently does not pay attention to modeling the processes of heating and melting of hydrocarbon mixtures, such as vaseline, paraffin, fats, lanolin and others. The issue of optimization of heating and melting processes, calculations of necessary process parameters (speed and depth of thermal front penetration, etc.) and equipment, avoidance of repetition for each hydrocarbon mixture of experimental studies shows the need to develop a mathematical model of these processes. For the method of melting a substance placed in a cylindrical tank, based on the movement of a disc heating element under the action of gravity during melting and overflow of molten substance through the gaps between the disc and the walls of the tank, simulation has been carried out. Simulation of the melt flow in the annular gap is presented, which describes the laminar flow under the influence of the pressure drop and the velocity of the vessel wall relative to the heater, and the melt flow under the heater.

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