scholarly journals Homogenization of the interfacial bonding of compound-cast AA7075/6060 bilayer billets by co-extrusion

2021 ◽  
Author(s):  
Hui Chen ◽  
Danai Giannopoulou ◽  
Thomas Greß ◽  
Jonas Isakovic ◽  
Tim Mittler ◽  
...  
Keyword(s):  
Thermal Conditions ◽  
Hot Extrusion ◽  
Interfacial Bonding ◽  
Cast Billet ◽  
Process Chain ◽  
Good Corrosion Resistance ◽  
The Core ◽  
Metallurgical Bonding ◽  
Compound Casting ◽  
Casting Parameter

AbstractA process chain of compound casting and co-extrusion of AA7075/6060 bilayer billets is introduced to manufacture hybrid components with strength in the core and good corrosion-resistance in the shell. Using optimized compound casting parameter, metallurgical bonding between the shell AA6060 and the core AA7075 can be achieved through remelting and recrystallization of the substrate AA7075. The locally unequal thermal conditions at the interface induces partially weak bonding. The bonding strength in greater distance from the casting gate is generally lower. Hot extrusion is applied to improve the interfacial bonding. Comparisons of the microstructure and the shear strength between as-cast billet and extrudate present the homogenization of the interfacial bonding through the process chain.

scholarly journals Microstructure and Mechanical Properties of Galvanized-45 Steel/AZ91D Bimetallic Material by Liquid-Solid Compound Casting

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1651 ◽  
Author(s):  
Jun Cheng ◽  
Jian-hua Zhao ◽  
Jin-yong Zhang ◽  
Yu Guo ◽  
Ke He ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Corrosion Current ◽  
Eutectic Structure ◽  
Galvanized Steel ◽  
X Ray Diffraction ◽  
Solid Compound ◽  
Metallurgical Bonding ◽  
Compound Casting ◽  
Bimetallic Material ◽  
Bimetallic Materials

A connection between hot-dip galvanized 45 steel and AZ91D was achieved by liquid-solid compound casting to achieve one material with a better mechanical performance and a light weight. The microstructure and properties of galvanized-steel/AZ91D bimetallic materials were investigated in this study. A scanning electron microscopy (SEM), an energy dispersive spectroscopy (EDS), and an X-ray diffraction (XRD) were applied to analyze the microstructure evolution and formation mechanism of the galvanized 45 steel/AZ91D interface zone which could be divided into three layers. Among three different layers, the layer close to AZ91D was composed of α-Mg and an eutectic structure (α-Mg + MgZn). The intermediate layer was comprised of an eutectic structure (α-Mg + MgZn), and the layer adjacent to 45 steel consisted of α-Mg and FeAl3. Furthermore, galvanized-45 steel/AZ91D bimetallic material had better shear strength than the bare-45 steel/AZ91D metallic material which can indicate that owing to the formation of metallurgical bonding, the adhesive strength of galvanized-steel and AZ91D was improved to 11.81 MPa. In addition, the fact that corrosion potential increased from −1.493 V to −1.143 V and corrosion current density changed from 3.015 × 10−5 A/cm2 to 1.34 × 10−7 A/cm2 implied that the corrosion resistance of galvanized-steel/AZ91D was much better than AZ91D.

scholarly journals Development and Optimization of Tin/Flux Mixture for Direct Tinning and Interfacial Bonding in Aluminum/Steel Bimetallic Compound Casting

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5642
Author(s):  
Mohamed Ramadan ◽  
Abdulaziz S. Alghamdi ◽  
K. M. Hafez ◽  
Tayyab Subhani ◽  
K. S. Abdel Halim
Keyword(s):  
Carbon Steel ◽  
Steel Substrate ◽  
Volume Ratio ◽  
Solid Substrate ◽  
Interfacial Bonding ◽  
Al Alloy ◽  
Compound Casting ◽  
Bonding Area ◽  
Bearing Alloy

Interfacial bonding highly affects the quality of bimetallic bearing materials, which primarily depend upon the surface quality of a solid metal substrate in liquid–solid compound casting. In many cases, an intermediate thin metallic layer is deposited on the solid substrate before depositing the liquid metal, which improves the interfacial bonding of the opposing materials. The present work aims to develop and optimize the tinning process of a solid carbon steel substrate after incorporating flux constituents with the tin powder. Five ratios of tin-to-flux—i.e., 1:1, 1:5, 1:10, 1:15, and 1:20—were used for tinning process of carbon steel solid substrate. Furthermore, the effect of volume ratios of liquid Al-based bearing alloy to solid steel substrate were also varied—i.e., 5:1, 6.5:1 and 8.5:1—to optimize the microstructural and mechanical performance, which were evaluated by interfacial microstructural investigation, bonding area determination, hardness and interfacial strength measurements. It was found that a tin-to-flux ratio of 1:10 offered the optimum performance in AlSn12Si4Cu1/steel bimetallic materials, showing a homogenous and continuous interfacial layer structure, while tinned steels using other percentages showed discontinuous and thin layers, as in 1:5 and 1:15, respectively. Furthermore, bimetallic interfacial bonding area and hardness increased by increasing the volume ratio of liquid Al alloy to solid steel substrate. A complete interface bonding area was achieved by using the volume ratio of liquid Al alloy to solid steel substrate of ≥8.5.

scholarly journals SPX Benchmark Part I: Results of Static Neutronics

2021 ◽  
Author(s):  
Alexander Ponomarev ◽  
Konstantin Mikityuk ◽  
Liang Zhang ◽  
Evgeny Nikitin ◽  
Emil Fridman ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Power Distribution ◽  
Reactor Core ◽  
Thermal Conditions ◽  
Reaction Rates ◽  
Second Phase ◽  
Reference Solution ◽  
Transient Behaviour ◽  
The Core ◽  
Reactivity Coefficients

Abstract In the paper, the specification of a new neutronics benchmark for a large Sodium cooled Fast Reactor core and results of modelling by different participants are presented. The neutronics benchmark describes the core of the French sodium cooled reactor Superphénix at its startup configuration, which in particular was used for experimental measurement of reactivity characteristics. The benchmark consists of the detailed heterogeneous core specification for neutronic analysis and results of the reference solution. Different core geometries and thermal conditions from cold “as fabricated” up to full power were considered. The reference Monte Carlo solution of Serpent 2 includes data on multiplication factor, power distribution, axial and radial reaction rates distribution, reactivity coefficients and safety characteristics, control rods worth, kinetic data. The results of modelling with seven other solutions using deterministic and Monte Carlo methods are also presented and compared to the reference solution. The comparisons results demonstrate appropriate agreement of evaluated characteristics. The neutronics results will be used in the second phase of the benchmark for evaluation of transient behaviour of the core.

Engineering the Core–Shell-Structured NCNTs-Ni2Si@Porous Si Composite with Robust Ni–Si Interfacial Bonding for High-Performance Li-Ion Batteries

Langmuir ◽  
2019 ◽  
Vol 35 (19) ◽  
pp. 6321-6332 ◽  
Author(s):  
Ming Chen ◽  
Qiang-Shan Jing ◽  
Hai-Bin Sun ◽  
Jun-Qi Xu ◽  
Zhong-Yong Yuan ◽  
...  
Keyword(s):  
High Performance ◽  
Interfacial Bonding ◽  
Core Shell ◽  
Li Ion Batteries ◽  
Porous Si ◽  
The Core ◽  
Li Ion

Preparing Aluminum Foam Sandwich Panels by the Pack-Rolling-Powder Metallurgy Foaming Technique

2010 ◽  
Vol 154-155 ◽  
pp. 613-616 ◽  
Author(s):  
Bin Na Song ◽  
Guang Chun Yao ◽  
Guo Yin Zu ◽  
Lei Wang ◽  
Hua Ding
Keyword(s):  
Rolling Process ◽  
Sem Analysis ◽  
Interfacial Bonding ◽  
Pack Rolling ◽  
Cell Structures ◽  
Micro Cracks ◽  
Metallurgical Bonding ◽  
Precursor Material ◽  
Foaming Temperature

Billets of AFS with the thickness of 4.9 millimeters were manufactured by pack rolling process. SEM analysis for interfacial bonding and cell structures of AFS were carried out in detail. The results show that surface quality of the panel after pack rolling is obviously improved as compared to powder composite rolling using Al sheets. Macro-cracks of face sheets also completely disappear. The interfacial bonding in between Al tube and foamable precursor material have no micro-cracks and the existence of gap. Metallurgical bonding between Al face sheets and the core Al foams and uniform cell structures of AFS are achieved as the foaming temperature and foaming time are 700°C and 2 minutes, respectively.

scholarly journals Fabrication of Carbon Nanotubes and Rare Earth Pr Reinforced AZ91 Composites by Powder Metallurgy

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Ning Li ◽  
Hong Yan ◽  
Qingjie Wu ◽  
Zeyu Cao
Keyword(s):  
Mechanical Properties ◽  
Rare Earth ◽  
Powder Metallurgy ◽  
Extrusion Direction ◽  
Milled Powder ◽  
Hot Extrusion ◽  
Interfacial Bonding ◽  
Tensile Fracture ◽  
Az91 Alloy ◽  
The Matrix

AbstractIt can be known from a large number of research results that improving the dispersibility of CNTs can effectively optimize the mechanical properties of the corresponding metal matrix composites. However, the crucial issue of increasing the bonding of CNTs and the matrix is still unsolved. In this paper, a novel method was developed to increase interfacial bonding strength by coating titanium oxide (TiO2) on the surface of CNTs. The rare earth Pr and TiO2@CNTs-reinforced AZ91matrix composites were successfully fabricated by powder metallurgy. Hot press sintering and hot extrusion of the milled powder was performed. After hot extrusion, the influence of TiO2@CNTs on the microstructure and mechanical properties of the composites were investigated. The results showed that the coating process can improve the distribution of CNTs in Mg alloy. The CNTs refined the grains of the matrix, and the CNTs were presented throughout the extrusion direction. When the TiO2@CNTs content was 1.0 wt.%, the yield strength (YS), ultimate tensile strength (UTS), and elongation of the alloy attained maximum values. The values were improved by 23.5%, 82.1%, and 40.0%, respectively, when compared with the AZ91 alloy. Good interfacial bonding was achieved, which resulted in an effective tensile loading transfer at the interface. CNTs carried the tensile stress and were observed on the tensile fracture.

scholarly journals How dolphins use their blubber to avoid heat stress during encounters with warm water

1999 ◽  
Vol 276 (4) ◽  
pp. R1188-R1194
Author(s):  
M. E. Heath ◽  
S. H. Ridgway
Keyword(s):  
Heat Stress ◽  
Heat Flow ◽  
Rectal Temperature ◽  
Thermal Conditions ◽  
Inshore Water ◽  
The Core ◽  
Metabolic Heat ◽  
Normal Core ◽  
Simple Protocol ◽  
Expected Increase

Dolphins have been observed swimming in inshore tropical waters as warm as 36–38°C. A simple protocol that mimicked the thermal conditions encountered by a dolphin moving from cool pelagic to warm inshore water was used to determine how dolphins avoid hyperthermia in water temperatures (Tw) at and above their normal core temperature (Tc). Tw (2 sites), rectal temperature (Tre; 3 depths), and skin temperature (Tsk; 7 sites) and rate of heat flow (4–5 sites) between the skin and the environment were measured while the dolphin rested in a chamber during a 30-min baseline and 40–60 min while water was warmed at ∼0.43°C/min until temperatures of 34–36°C were attained. Instead of the expected increase, Treconsistently showed declines during the warming ramp, sometimes by amounts that were remarkable both in their magnitude (1.35°C) and rapidity (8–15 min). The reduction in Tre occurred even while heat loss to the environment was prevented by continued controlled warming of the water that kept Tw slightly above Tsk and while metabolic heat production alone should have added 1.6–2°C/h to the Tc. This reduction in Tc could only be due to a massive redistribution of heat from the core to the blubber layer.

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