Growth structures of al-4.5 wt pct cu alloys with dendrite growth directions differing from the heat flow direction

1978 ◽  
Vol 9 (12) ◽  
pp. 1795-1800 ◽  
Author(s):  
Hiroshi Kato ◽  
Takateru Umeda
Keyword(s):  
Heat Flow ◽  
Flow Direction ◽  
Dendrite Growth ◽  
Cu Alloys ◽  
Heat Flow Direction

scholarly journals Influence of heat flow direction on solder ball interfacial layer

2018 ◽  
Vol 69 (4) ◽  
pp. 305-310 ◽  
Author(s):  
Alexandr Otáhal ◽  
Ivan Szendiuch
Keyword(s):  
Heat Flow ◽  
Flow Direction ◽  
Intermetallic Layer ◽  
Point Of View ◽  
Infrared Heating ◽  
Root Mean Square Roughness ◽  
Sac305 Solder ◽  
Heat Flow Direction ◽  
Solder Balls ◽  
Bga Package

Abstract This paper deals with the research of an intermetallic layer of SAC305 solder balls soldered from three directions of the heat flow in the ball-attach process for BGA package. From the point of view of the heat flow direction, the samples were soldered by infrared heating. The heat sources were placed on the top, bottom and both lateral sides of the BGA package. After the solder balls-attach process, a metallographic cross-section was performed, followed by selective etching to visualize the relief of the intermetallic layer. Images of the interfacial between the solder and solder pad were taken from the created samples, followed by measurement of the average thickness and root mean square roughness of the intermetallic layer. The results showed changes in the intermetallic layer. The largest thickness of the intermetallic layer was observed on samples soldered from the top and both sides. Soldering with the bottom infrared heater resulted to the smallest thickness of the intermetallic layer. The same trend was in the roughness of the IMC layer. The greatest roughness was found for samples soldered by the top and both side heaters. The top soldered samples exhibit the smallest roughness.

scholarly journals Orientation and Microstructure Evolution of Al-Al2Cu Regular Eutectic Lamellar Bifurcating in an Abruptly Changing Velocity under Directional Solidification

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1004
Author(s):  
Ka Gao ◽  
Zan Zhang ◽  
Junliang Zhao ◽  
Dejian Sun ◽  
Fu Wang
Keyword(s):  
Heat Flow ◽  
Directional Solidification ◽  
Flow Direction ◽  
Solidification Rate ◽  
Lateral Diffusion ◽  
Interfacial Instability ◽  
Growth Orientation ◽  
Al2cu Phase ◽  
Heat Flow Direction ◽  
Solidification Microstructures

In an abruptly changing velocity under directional solidification, microstructures and the growth orientation of Al-Al2Cu eutectic lamellar were characterized. The change in solidification rate led to an interfacial instability, which results in a bifurcation of the eutectic lamella into new, refined lamellae. The growth orientation of the eutectic Al2Cu phase was also only in its (001) direction and more strongly oriented to the heat flow direction. The results suggest that the eutectic lamellar Al-Al2Cu bifurcation and the spacing adjustment may be caused by the rate determining lateral diffusion of the solutes after interfacial instability.

The importance of heat flow direction for reproducible and homogeneous freezing of bulk protein solutions

2013 ◽  
Vol 29 (5) ◽  
pp. 1212-1221 ◽  
Author(s):  
Miguel A. Rodrigues ◽  
Gustavo Balzan ◽  
Mónica Rosa ◽  
Diana Gomes ◽  
Edmundo G. de Azevedo ◽  
...  
Keyword(s):  
Heat Flow ◽  
Flow Direction ◽  
Protein Solutions ◽  
Heat Flow Direction ◽  
Homogeneous Freezing

scholarly journals Analysis of Temperature Field, Heat and Fluid Flow of Two-Phase Zone Continuous Casting Cu–Sn Alloy Wire

2016 ◽  
Vol 16 (1) ◽  
pp. 33-40 ◽  
Author(s):  
J. Luo ◽  
X. Liu ◽  
X. Wang
Keyword(s):  
Temperature Field ◽  
Fluid Flow ◽  
Heat Flow ◽  
Continuous Casting ◽  
Flow Direction ◽  
Phase Zone ◽  
Two Phase ◽  
Alloy Wire ◽  
Heat Flow Direction ◽  
Heat And Fluid Flow

Abstract Cu–4.7 wt. % Sn alloy wire with Ø10 mm was prepared by two-phase zone continuous casting technology, and the temperature field, heat and fluid flow were investigated by the numerical simulated method. As the melting temperature, mold temperature, continuous casting speed and cooling water temperature is 1200 °C, 1040 °C, 20 mm/min and 18 °C, respectively, the alloy temperature in the mold is in the range of 720 °C–1081 °C, and the solid/liquid interface is in the mold. In the center of the mold, the heat flow direction is vertically downward. At the upper wall of the mold, the heat flow direction is obliquely downward and deflects toward the mold, and at the lower wall of the mold, the heat flow deflects toward the alloy. There is a complex circular flow in the mold. Liquid alloy flows downward along the wall of the mold and flows upward in the center.

Thermoelectric Power of Gradient Fex(Al2O3)100-x Composite Films

2015 ◽  
Vol 233-234 ◽  
pp. 694-698 ◽  
Author(s):  
Oleg Stognei ◽  
Ahmed Al-Maliki ◽  
Alexander Sitnikov ◽  
Vladimir Makagonov
Keyword(s):  
Heat Flow ◽  
Temperature Gradient ◽  
Thermoelectric Power ◽  
Concentration Gradient ◽  
Flow Direction ◽  
Composite Films ◽  
Sputter Deposition ◽  
Deposition Technique ◽  
Opposite Edge ◽  
Heat Flow Direction

Nanocomposite Fex(Al2O3)100-x films with concentration gradient along the long axis of the samples (40 mm) have been obtained by sputter deposition technique and investigated. Based on the electric and magnetoresistive investigations the gradient Fex(Al2O3)100-x samples in which concentration of one edge of the sample is smaller than concentration of a percolation threshold while concentration of opposite edge of this sample is upper the threshold have been determined. Influence of the heat flow direction on the thermoelectric power of the gradient samples has been investigated. Hysteresis of the thermoelectric power is observed when temperature gradient direction is changed.

scholarly journals Advanced Modeling of Enclosed Airspaces to Determine Thermal Resistance for Building Applications

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7772
Author(s):  
Hamed H. Saber ◽  
David W. Yarbrough
Keyword(s):  
Heat Flow ◽  
Aspect Ratio ◽  
Thermal Resistance ◽  
Flow Direction ◽  
Total Heat Transfer ◽  
Temperature Variations ◽  
One Dimensional ◽  
Heat Flow Direction ◽  
R Value ◽  
The Impact

Enclosed airspaces to reduce heat flow have been recognized for well over 100 years. Airspaces with one or more reflective surfaces define reflective insulation (RI) assemblies, a product type used in walls, roofs, windows with multiple panes, curtain walls and skylights. The thermal resistance (R value) of airspaces depends on the emittance of all surfaces, airspace dimensions and orientation, heat flow direction and surfaces temperatures. The modeling of RI now includes CFD coupled with radiation to quantify the total heat transfer. This study compares a validated model for airspace R values with existing methods such as ISO 6946 and hot-box results that provide the R values in the ASHRAE Handbook of Fundamentals. The existing methods do not include an airspace aspect ratio. This study showed that the aspect ratio can impact the R value by a factor of two. The impact of aspect ratio was calculated for double airspaces variation such as that for single airspaces. The present calculations are two-dimensional and also consider all the bounding airspace surfaces, while previous methods are one-dimensional and do not include surface temperature variations or detailed radiative transport.

Thermal protection by integration of vacuum insulation panel in liquid-cooled active thermal management for electronics package exposed to thermal radiation

2021 ◽  
pp. 1-34
Author(s):  
Midhun V. C. ◽  
S Suresh
Keyword(s):  
Heat Flow ◽  
Thermal Management ◽  
Thermal Insulation ◽  
Heat Dissipation ◽  
Flow Direction ◽  
Cooling Load ◽  
Vacuum Insulation ◽  
Heat Flow Direction ◽  
Thermal Irradiation ◽  
Vacuum Insulation Panel

Abstract Thermal Management Systems (TMSs) working for electronics packages under harsh environments like intense thermal radiation is challenging due to external thermal interactions. Thermal insulation protection for TMS is very critical in these harsh conditions. An experimental set-up was developed to analyse the effect of insulation protection against thermal irradiation over a pumped liquid-cooling Active Thermal Management System (ATMS) with varying heat dissipation rate (0 - 4.2 kW/m2), thermal irradiation (0.85-3.80 kW/m2) and coolant temperature (15-25 C). Three configurations of ATMS are considered in the experimental study- ATMS without thermal insulation protection, ATMSs integrated with Cellulose Fibre Insulation (CFI) and Vacuum Insulation Panel (VIP). The effect of insulation on each parameter in all three ATMS configurations over the temperature of the electronics component, cooling load, and nature of heat flow in ATMS was analysed. VIP outperformed CFI on achieving a significant reduction in temperature of electronics systems (35.67 %) and cooling load (45.64 %) experienced by the ATMS. VIP effectively reduced the impact of temperature and cooling load change in ATMS against change in thermal irradiation. The study concluded that thermal insulation protection was most effective at high thermal irradiation and low heat dissipation rate. Heat Flow Direction Index (HFDI) concept was developed to find the nature of heat transfer direction in ATMS without temperature distribution trend. Heat generation rate and irradiation possess significant influence over the nature of heat flow direction.

scholarly journals Composites with Excellent Insulation and High Adaptability for Lightweight Envelopes

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 53 ◽  
Author(s):  
Liang Guo ◽  
Wenbin Tong ◽  
Yexin Xu ◽  
Hong Ye
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Flow Direction ◽  
Base Material ◽  
Core Material ◽  
Insulation Materials ◽  
The Core ◽  
Cross Section Area ◽  
Heat Flow Direction ◽  
Section Area

Lightweight insulation materials are widely used in lightweight buildings, cold-chain vehicles and containers. A kind of insulation composite, which can combine the super insulation of state-of-the-art insulation materials or structures and the machinability or adaptability of traditional insulation materials, was proposed. The composite consists of two components, i.e., polyurethane (PU) foam as the base material and vacuum insulation panel (VIP) or silica aerogel as the core material. The core material is in plate shape and covered with the base material on all sides. The thermal conductivity of the core material is nearly one order lower than that of the base material. The effective thermal conductivity of the insulation composite was explored by simulation. Simulation results show that the effective thermal conductivity of the composite increases with the increase of the thermal conductivity of the core material. The effective thermal conductivities of the composites decrease with the increase of the cross-section area of the core material perpendicular to heat flow direction and the thicknesses of the core material parallel with heat flow direction. These rules can be elucidated by a series-parallel mode thermal resistance network method, which was verified by the measured results. For composite with a VIP as the core material, when the cross-section area and thickness of the VIP are respectively larger than 60% and 21% of the composite, the composite’s effective thermal conductivity can be 50% or less than that of the base material. Simulated heat loss of the envelope adopting the insulation composites with VIP as the core material is nearly a half of that of the envelope adopting traditional insulation materials.

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