Effect of Solute Atoms on the Thermal Property of Mg Alloys

2015 ◽  
Vol 817 ◽  
pp. 319-324
Author(s):  
Jia Wei Yuan ◽  
Kui Zhang ◽  
Xing Gang Li ◽  
Ting Li ◽  
Yong Jun Li ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Lattice Distortion ◽  
Atomic Radius ◽  
Lattice Parameter ◽  
Mg Alloys ◽  
Significant Difference ◽  
Solute Atoms ◽  
The Difference ◽  
Zn Alloys

The reason for the distinct difference in the thermal conductivities of different series of Mg alloys was investigated.The crystallographic lattice parameter and the thermal conductivity of Mg–Zn, Mg–Al, and Mg–Gd binary alloys, which all contain the same atomic percentage of the solutes were measured. The Mg–Zn alloys exhibited the highest thermal conductivity and the smallest lattice distortion, and Mg–Gd alloys exhibited lowest thermal conductivity and largest lattice distortion, respectively. Results indicate that the thermal conductivity of the Mg alloys depends on the difference in atomic radius of the solute and matrix atoms. Therefore, the reason for the Mg-7Gd-5Y-0.5Nd-0.5Zr alloy components have excellent thermal resistance is the serious lattice distortion caused by the significant difference in the atomic radius between the solute and matrix atoms.

scholarly journals THERMOPHYSICAL PROPERTIES OF ALLOY COMPOSITIONS (2Bi2O3∙B2O3)100-x(2Bi2O3∙3GeO2)x (x=0, 10, 50)

2021 ◽  
pp. 44-48
Author(s):  
S.I. Bananyarli ◽  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Phase Transitions ◽  
Thermal Resistance ◽  
Temperature Dependence ◽  
Thermophysical Properties ◽  
Chemical Bonds ◽  
Temperature Range ◽  
The Difference

The termophisical properties, namely, the temperature dependence of thermal conductivity, thermal resistance and heat capacity of the allays compositions (2Bi2O3∙B2O3)100-x (2Bi2O3∙3GeO2)x in the (300–600) K temperature range have ligated been invest. An increase in thermal conductivity χ(T) above 500 K is probably associated with the softening of alloys and the presence of blurred phase transitions, which are accompanied by partial breaking of chemical bonds. It was revealed that the heat capacity in alloys of the compositions (2Bi2O3∙B2O3)100-x (2Bi2O3∙3GeO2)x increases with an increase in the GeO2 concentration. In the studied samples, that showed their own disorder during solidification, the thermal conductivity is strongly reduced due to the enhancement of the anharmonicity of phonon – phonon interactions. İn turn a small "disorder" introduced by defects due to the difference in masses is not noticeable against the background of the huge "disorder" inherent in oxide substances

Theoretical Investigation on Effective Thermal Conductivity of a Disk-Shaped Composite System

2010 ◽  
Author(s):  
Yasushi Koito ◽  
Toshio Tomimura ◽  
Shuichi Torii
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Composite System ◽  
Microsoft Excel ◽  
Resistance Network ◽  
Estimation Equations ◽  
The Difference ◽  
Wiring Board

This paper addresses the methodology to estimate the effective thermal conductivity of the wiring board, where the metal wiring network is very complicated and then the thermal conductivity of the metal wiring is more than 1000 times higher than that of the resign board. Based on the concept of analogy between the electric and the thermal resistance network, two types of estimation equations are derived by dividing the composite system parallel or perpendicular to the heated/cooled surface. When the ratio of higher to lower thermal conductivities is less than 10, the estimated values by these equations agree with each other. However, the difference is clearly found between them when the ratio is larger than 100. The estimated values are moreover compared with the exact solutions, which are obtained by numerical simulation of heat transfer using Microsoft Excel, and then the applicability of the present estimation methodology is discussed. It is found that the thermal resistance network obtained by dividing the composite system perpendicular to the heated/cooled surface is effective to estimate the effective thermal conductivity of the composite system.

EVALUATION ON THE THERMAL AND STRUCTURAL PROPERTIES OF COPPER ALUMINUM OXIDE (Cu-Al2O3) THIN FILM ON AL SUBSTRATE: EFFECT OF ANNEALING TEMPERATURE

2018 ◽  
Vol 25 (07) ◽  
pp. 1950017
Author(s):  
WEI QIANG LIM ◽  
SUBRAMANI SHANMUGAN ◽  
MUTHARASU DEVARAJAN
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Structural Properties ◽  
Heat Dissipation ◽  
Rf Magnetron Sputtering ◽  
Xrd Analysis ◽  
Annealed Sample ◽  
Significant Difference ◽  
The Difference ◽  
Copper Aluminum

Layer stacking technique is incorporated in the deposition of copper aluminium oxide (Cu-Al2O3) thin films on Al substrate using RF magnetron sputtering. The Cu/Al2O3 stack is sputtered using Cu and Al2O3 target at ambient temperature and then annealed to yield the resultant Cu-Al2O3 films. The structural properties of the films are investigated through X-ray Diffraction (XRD) whereas the chemical structure of the films is studied using Fourier-transform infrared (FTIR). The thermal conductivity analyzer is used to evaluate the thermal properties of coated film on the Al substrate. XRD analysis revealed that the synthesized films are polycrystalline film composed mainly of CuAl2O4 phase along with Al2O3 and CuO phases. The thermal properties of Cu-Al2O3 coated Al substrates showed improvement in terms of thermal conductivity and diffusivity compared to bare Al substrate. The Cu-Al2O3 sample annealed at 400∘C exhibited a significant difference in thermal conductivity ([Formula: see text][Formula: see text]W/mK) compared to bare Al. The difference in thermal conductivity displayed by the annealed sample verified that TIMs did enhance the thermal path of entire substrate by allowing the heat to dissipate to surrounding environment more efficiently, thereby improving the heat dissipation system. From the results observed, it can be concluded that Cu-Al2O3 coated Al substrate can be made as alternative TIM in thermal management application.

Study of solid-solution hardening in binary aluminium-based alloys

Open Physics ◽  
2005 ◽  
Vol 3 (3) ◽  
Author(s):  
Mohamed Draissia ◽  
Mohamed-Yacine Debili
Keyword(s):  
Solid Solution ◽  
Lattice Parameter ◽  
Solid Solution Hardening ◽  
Solid Solution Formation ◽  
Cu Films ◽  
Sputtered Films ◽  
Solution Formation ◽  
Solute Atoms ◽  
The Difference ◽  
Low Solubility

AbstractSolid-solution formation in binary aluminium-based alloys is due essentially to the combined effects of the size and valence of solvent and solute atoms, as expected by the four Hume-Rothery rules. The lattice parameter of aluminium in the solid solution of the sputtered Al−Fe films is [Al-a (Å)=4.052−6.6×10−3Y]. The increasing and decreasing evolution of the lattice parameter of copper [Cu-a (Å)=3.612+1.8×10−3Z] and aluminium [Al-a (Å)=4.048−1.6×10−3X] in the sputtered Al-1.8 to 92.5 at. % Cu films is a result of the difference in size between the aluminium and copper atoms. The low solubility of copper in aluminium (<1.8 at % Cu) is due to the valences of solvent and solute atoms in contrast with other sputtered films prepared under similar conditions, such as Al−Mg (20 at. % Mg), Al−Ti (27 at. % Ti), Al−Cr (5at. % Cr) and Al−Fe (5.5 at. % Fe) where the solubility is due to the difference in size.

scholarly journals Avoiding Being Trapped in False Analogical Modeling of Composite Wall Thermal Resistance

2018 ◽  
Vol 1 (2) ◽  
pp. 69-77
Author(s):  
Mohammed Aliedeh*
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flow ◽  
Thermal Resistance ◽  
Detailed Calculation ◽  
True Value ◽  
Parallel Wall ◽  
Composite Wall ◽  
The Difference ◽  
Composite Walls

Because Analogy is considered as a double-edged sword, thermal engineers should be cautious in analogical maneuvering between electrical and thermal domains in order not to be slipped into building misconceptions about thermal resistance concept. Composite wall thermal resistance (CWTR) modeling is one of the practical examples that illustrates the probability of misusing analogy. Heat transfer undergraduate textbooks coverage of CWTR suffers a lean towards “cookbook” coverage that reports concise statements that lack deep clarification and illustration. Transparent Thinking Approach (TTA) is employed to present a detailed calculation and illustration of a typical CWTR modeling based on isothermal and adiabatic assumptions. The calculation of a typical CWTR for different values of wall thermal conductivities shows that the difference in parallel walls thermal conductivity is creating a large discrepancy that may reach 80% between heat flows calculated based on isothermal and adiabatic assumptions. It is found that for a series-parallel arrangement of composite walls with high difference in parallel wall thermal conductivity values, the true value of heat flow is bracketed between the isothermal and adiabatic heat flow values. The transparent way of presenting CWTR modeling can be readily included in any standard heat transfer textbook and result in greatly enhancing CWTR modeling coverage.

Application of convergent-beam illumination methods to the study of lattice distortion across the interface

1992 ◽  
Vol 50 (1) ◽  
pp. 232-233
Author(s):  
Zuzanna Liliental-Weber ◽  
T. Kaneyama ◽  
M. Terauchi ◽  
M. Tanaka
Keyword(s):  
Spatial Resolution ◽  
Lattice Distortion ◽  
Large Angle ◽  
Lattice Parameter ◽  
Gaas Layer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Accuracy Measurement ◽  
The Difference ◽  
Convergent Beam

A high accuracy measurement of the lattice parameter can be obtained by x-ray diffraction. However, these methods have low spatial resolution and are limited by sample thickness. Therefore, for heterolayers much better information about local distortions near the interface can be obtained by electron microscopy using convergent-beam illumination. Large-angle convergent-beam electron diffraction (LACBED) patterns and convergent-beam imaging (CBIM) were applied to study of the lattice distortion across the interface of the GaAs epilayer grown on [001] GaAs substrate and the GaAs layer grown at 200°C (called the low-temperature (LT) layer). These LT GaAs layers are grown by molecular beam epitaxy from As oversaturation and are known to be As rich. Particle-induced x-ray studies reveal up to 1.5 % extra As. This excess As leads to the expansion of the lattice parameter up to 0.15% when measured by x-ray diffraction along the (004) reflection. From this study, it was expected that a cubic expansion of the lattice parameter would be equal in all three directions. However, TEM studies do not reveal the formation of dislocations at the interface, which would be expected taking into account the difference in the lattice parameter across the interface . Convergence beam illumination methods were applied to study in detail the strain, lattice parameter variation, and crystallographic distortion across the interface, since these methods have spatial resolution several orders of magnitude higher than x-ray diffraction. A CBED pattern taken in the substrate and in the layer with an incidence close to the [530] direction (exact orientation [0.869 0.495 0]) reveals the lattice parameter change, since the position of the cross of the 1113 and 1113 lines changes when an electron beam is placed in the substrate and the layer, respectively (Fig. la,b).

scholarly journals Elaboration and Characterization of Thermal Insulating Material Based on the Synergy of Natural Coconut Husk and Disposable Diaper Pads Fibers

2019 ◽  
Vol 17 ◽  
pp. 21-32
Author(s):  
Lenrah Rinna A. Mascariñas ◽  
Romnick M. Ureta ◽  
Siegfred M. Mejico ◽  
Czarina D. Servando
Keyword(s):  
Thermal Conductivity ◽  
Synergistic Effect ◽  
Thermal Resistance ◽  
Burning Rate ◽  
Insulating Material ◽  
Coconut Husk ◽  
Thermal Insulating ◽  
Significant Difference ◽  
Set Up ◽  
Disposable Diapers

Materials based on highly porous fibers are now becoming increasingly popular as thermal insulators to fight severely increasing temperatures due to climate change (Khedari, et al., 2004). In this study, fibers from solid waste materials like coconut husk and absorbent pads of used disposable diapers were evaluated for their synergistic effect as thermal insulating material. Dried coconut husk fibers and cleaned used disposable diapers were heated at 1500C-3000C for 2 hours and then molded to make pads. Scanning Electron Microscopy and HD digital microscope were used in the analytical imaging of the fibers. Fiber pads from coconut husk fibers, used disposable diapers and their combination, and polyethylene foam (+control) were evaluated for their burning rate based on ASTM D 1992 while thermal conductivity, and thermal resistance were obtained using the testing hot box (Frawley & Kennedy, 2007). The morphology of the coconut husk fibers with used disposable diapers showed thicker and rougher surface with foamy coatings which confirmed porous fiber structure. One-Factor ANOVA showed significant difference among the different set-ups for burning rate (F=926.506; p=0.000), thermal conductivity (F=203.993; p=0.000), and thermal resistance (F=197.820; p=0.000) wherein the set-up for the combination of the coconut husk fibers and used disposable diapers exhibits satisfactory burning rate (M=3.268), lowest thermal conductivity (M=0.037) and highest thermal resistance (M=0.273).The results affirm that the natural coconut husk fibers and used disposable diapers have synergistic effect for better thermal properties, thus, producing a more effective and safer thermal insulating material.

Cranial crassicaudiasis in two coastal dolphin species from South Africa is predominantly a disease of immature individuals

2020 ◽  
Vol 139 ◽  
pp. 93-102 ◽  
Author(s):  
MF Van Bressem ◽  
P Duignan ◽  
JA Raga ◽  
K Van Waerebeek ◽  
N Fraijia-Fernández ◽  
...  
Keyword(s):  
South Africa ◽  
Bone Development ◽  
Bottlenose Dolphins ◽  
Fatal Outcome ◽  
Population Level ◽  
Cape Coast ◽  
Osteolytic Lesions ◽  
Immune Mediated ◽  
Significant Difference ◽  
The Difference

Crassicauda spp. (Nematoda) infest the cranial sinuses of several odontocetes, causing diagnostic trabecular osteolytic lesions. We examined skulls of 77 Indian Ocean humpback dolphins Sousa plumbea and 69 Indo-Pacific bottlenose dolphins Tursiops aduncus, caught in bather-protecting nets off KwaZulu-Natal (KZN) from 1970-2017, and skulls of 6 S. plumbea stranded along the southern Cape coast in South Africa from 1963-2002. Prevalence of cranial crassicaudiasis was evaluated according to sex and cranial maturity. Overall, prevalence in S. plumbea and T. aduncus taken off KZN was 13 and 31.9%, respectively. Parasitosis variably affected 1 or more cranial bones (frontal, pterygoid, maxillary and sphenoid). No significant difference was found by gender for either species, allowing sexes to be pooled. However, there was a significant difference in lesion prevalence by age, with immature T. aduncus 4.6 times more likely affected than adults, while for S. plumbea, the difference was 6.5-fold. As severe osteolytic lesions are unlikely to heal without trace, we propose that infection is more likely to have a fatal outcome for immature dolphins, possibly because of incomplete bone development, lower immune competence in clearing parasites or an over-exuberant inflammatory response in concert with parasitic enzymatic erosion. Cranial osteolysis was not observed in mature males (18 S. plumbea, 21 T. aduncus), suggesting potential cohort-linked immune-mediated resistance to infestation. Crassicauda spp. may play a role in the natural mortality of S. plumbea and T. aduncus, but the pathogenesis and population level impact remain unknown.

Perbedaan Penggunaan Antikoagulan K2EDTA DAN K3EDTA Terhadap Hasil Pemeriksaan Indeks Eritrosit

2018 ◽  
Vol 1 (2) ◽  
pp. 114
Author(s):  
Wahdaniah Wahdaniah ◽  
Sri Tumpuk
Keyword(s):  
Screening Test ◽  
Venous Blood ◽  
The Body ◽  
Ethylene Diamine ◽  
P Value ◽  
Cross Sectional ◽  
Significant Difference ◽  
Ethylene Diamine Tetra Acetate ◽  
The Difference ◽  
Index Value

Abstract: Routine blood examination is the earliest blood test or screening test to determine the diagnosis of an abnormality. Blood easily froze if it is outside the body and can be prevented by the addition of anticoagulants, one of which Ethylene Diamine Tetra Acetate (EDTA). Currently available vacuum tubes containing EDTA anticoagulants in the form of K2EDTA and K3EDTA. K3EDTA is usually a salt that has better stability than other EDTA salts because it shows a pH approaching a blood pH of about 6.4. The purpose of this research is to know the difference of erythrocyte index results include MCH, MCV and MCHC using K3EDTA anticoagulant with K2EDTA. This research is a cross sectional design. This study used venous blood samples mixed with K2EDTA anticoagulant and venous blood mixed with K3EDTA anticoagulants, each of 30 samples. Data were collected and analyzed using paired different test. Based on data analysis that has been done on MCH examination, p value <0,05 then there is a significant difference between samples with K3EDTA anticoagulant with K2EDTA to erythrocyte index value. Then on the examination of MCV and MCHC obtained p value <0.05 then there is no significant difference between samples with K3EDTA anticoagulant with K2EDTA to erythrocyte index value.Abstrak: Pemeriksaan darah rutin merupakan pemeriksaan darah yang paling awal atau screening test untuk mengetahui diagnosis suatu kelainan. Darah mudah membeku jika berada diluar tubuh dan bisa dicegah dengan penambahan antikoagulan, salah satunya Ethylene Diamine Tetra Acetate (EDTA). Dewasa ini telah tersedia tabung vakum yang sudah berisi antikoagulan EDTA dalam bentuk  K2EDTA dan  K3EDTA. K3EDTA  biasanya berupa garam yang mempunyai stabilitas yang lebih baik dari garam EDTA yang lain karena menunjukkan pH yang mendekati pH darah yaitu sekitar 6,4. Tujuan dari penelitian ini adalah untuk mengetahui perbedaan hasil indeks eritrosit meliputi MCH, MCV dan MCHC menggunakan antikoagulan K3EDTA dengan K2EDTA. Penelitian ini merupakan penelitian dengan desain cross sectional. Penelitian ini menggunakan sampel darah vena yang dicampur dengan antikoagulan K2EDTA dan darah vena yang dicampur dengan antikoagulan K3EDTA, masing-masing sebanyak 30 sampel. Data dikumpulkan dan dianalisis menggunakan uji beda berpasangan. Berdasarkan analisis data yang telah dilakukan pada pemeriksaan MCH didapatkan nilai p < 0,05 maka ada perbedaan yang signifikan antara sampel dengan antikoagulan K3EDTA dengan K2EDTA terhadap nilai indeks eritrosit. Kemudian pada pemeriksaan MCV dan MCHC didapatkan nilai p < 0,05 maka tidak ada perbedaan yang signifikan antara sampel dengan antikoagulan K3EDTA dengan K2EDTA terhadap nilai indeks eritrosit.

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