Effects of Melt Ultrasonic Treatment and Forming Processes on Thermo- Physical Properties of SiCp/Mg and (SiCp+Mg2Si)/Mg Composites

2021 ◽  
Vol 1035 ◽  
pp. 856-862
Author(s):  
Shu Sen Wu ◽  
Tian Guo ◽  
Shu Lin Lü ◽  
Wei Guo ◽  
Lan Qing Xia
Keyword(s):  
Thermal Conductivity ◽  
Ultrasonic Treatment ◽  
Coefficient Of Thermal Expansion ◽  
Gravity Casting ◽  
Average Coefficient ◽  
Molten Magnesium ◽  
Casting Porosity ◽  
Thermo Physical Properties ◽  
Thermal Conductivity Λ

The 10 vol% SiCp/Mg composites were prepared by external addition and stirring-casting method, and the hybrid reinforced (10 vol% SiCp+10 vol% Mg2Si)/Mg composites were prepared by combining in-situ method. The effects of melt ultrasonic treatment (UT) and forming processes on the thermophysical properties of the two composites were studied. The results show that UT can effectively disperse SiC particles in molten magnesium and reduce the casting porosity, while squeeze casting can significantly reduce the porosity of the composites, which can also significantly improve the thermal conductivity. The thermal conductivity (λ) of 10 vol.% SiCp/Mg composites squeeze casted after UT is 135.3 W/(mK) and the average coefficient of thermal expansion (CTE) is 19.95×10-6 K-1 at 293-373 K. Compared with gravity casting, the λ is increased by 17% and the CTE is reduced by 0.8%. The λ of (SiCp+Mg2Si)/Mg composite squeeze casted after UT is 132.4 W/(mK), and the CTE is 18.95×10-6 K-1, which is 27% lower than the CTE of pure magnesium.

The Effects of Different Architectures on Thermal Fatigue in Particle Reinforced MMC for Heat Sink Applications

2008 ◽  
Vol 59 ◽  
pp. 177-181 ◽  
Author(s):  
Michael Schöbel ◽  
G. Fiedler ◽  
Hans Peter Degischer ◽  
W. Altendorfer ◽  
Sebastien Vaucher
Keyword(s):  
Thermal Conductivity ◽  
Thermal Fatigue ◽  
Heat Sink ◽  
Coefficient Of Thermal Expansion ◽  
High Volume ◽  
Matrix Composites ◽  
Insulated Gate Bipolar Transistor ◽  
Igbt Modules ◽  
Synchrotron Tomography

Particle reinforced metal matrix composites are developed for heat sink applications. For power electronic devices like IGBT modules (Insulated Gate Bipolar Transistor) a baseplate material with high thermal conductivity combined with a low coefficient of thermal expansion is needed. Commonly AlSiC MMC are used with a high volume content of SiC particles (~ 70 vol.%). To improve the performance of these electronic modules particle reinforced materials with a higher thermal conductivity are developed for an advanced thermal management. For this purpose highly conducting diamond particles (TC ~ 1000 W/mK) are embedded in an Al matrix. These new diamond reinforced MMC were investigated concerning their thermal fatigue mechanisms compared to the common AlSiC MMC. Differences in reinforcement architecture and their effects on thermal fatigue damage were studied by in situ synchrotron tomography during thermal cycling.

scholarly journals Thermo-Physical Properties Measurement of Advanced TBC Materials with Pyrochlore and Perovskite Structures

2018 ◽  
Vol 778 ◽  
pp. 236-244 ◽  
Author(s):  
Noveed Ejaz ◽  
Liaqat Ali ◽  
Akhlaq Ahmad ◽  
Muhammad Mansoor ◽  
Muhammad Muneeb Asim ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Coefficient Of Thermal Expansion ◽  
Pyrochlore Structure ◽  
Conductivity Measurement ◽  
Aircraft Engine ◽  
Ceramic Materials ◽  
Scanning Calorimetry ◽  
Thermal Insulator ◽  
Thermo Physical Properties ◽  
Good Agreement

Thermal barrier coatings (TBCs) serve as thermal insulator in the hot region of an aircraft engine. Besides this, it also protects the underlying metal surface from the harsh corrosive and eroding environment. The associated lower thermal conductivity of TBC ceramic materials plays an important role in the improvement of thermal efficiency of the engine in term of increased combustion temperature and power. The thermal conductivity of the conventional yttria stabilized zirconia (YSZ) and three advanced ceramic materials with perovskite (CaZrO3) and pyrochlore structure (La0.75Nd0.25)2Zr2O7 & Nd2Ce2O7) have been determined using differential scanning calorimetry (DSC). With thin metallic disk on the ceramic samples of different heights were heated / scanned using a standard DSC apparatus. The results were evaluated for the thermal conductivity measurement using well established procedure /calculations. The analyzed results were compared with that of other techniques given by other researchers and found to be in good agreement with an error of 10-15%. The result of coefficient of thermal expansion (CTE) that was measured using a dilatometer up to 1273°K has also given.

Influence of Mg and Si in the Aluminum on the Thermo-Physical Properties of Pressureless Infiltrated SiCp/Al Composites

2009 ◽  
Vol 610-613 ◽  
pp. 546-553 ◽  
Author(s):  
Xian Liang Zhou ◽  
Ai Hua Zou ◽  
Xiao Zhen Hua ◽  
Jian Yun Zhang
Keyword(s):  
Thermal Conductivity ◽  
Physical Properties ◽  
Molten Aluminum ◽  
Coefficient Of Thermal Expansion ◽  
Interface Reaction ◽  
Element Content ◽  
Pressureless Infiltration ◽  
Matrix Elements ◽  
Si Content ◽  
Thermo Physical Properties

SiCp/Al composites based on different matrix elements Mg and Si content were fabricated by pressureless infiltration. Through microscope investigation by SEM and TEM, density examination, coefficient of thermal expansion (CTE) and thermal conductivity measuring by Netzsch DIL 402EP and Netzsch LFA 447 Nanoflash, the effects of Mg and Si in the aluminum on the thermo-physical properties of SiCp/Al composites was studied and analysed. The results showed that , adding Mg element in matrix enhaced the densification and thermal conductivity of composites, but meanwhile increased the CTE of SiCp/Al composites. When Mg element content was in higher than 6.3wt%, CTE of SiCp/Al composites increased obviously. Adding Si element in matrix markedly reduced the CTE of composites , but meanwhile decreased thermal conductivity of composites. When Si element content was higher than 5-9wt%,thermal conductivity of composites declined obviously. Adding Mg element in matrix improved the interface wet ability between molten aluminum and SiC particles, and adding Si element in matrix could control the formation of A14C3 which is a detrimental interface reaction product during the pressureless infiltration processing. Therefore, adding appropriate Mg in company with Si in matrix will be more benefit to enhance the integer properties of SiCp/Al composites.

Microstructure and Thermo-Physical Properties of TiB2/Si-30Al Composite for Electronic Packaging Applications

2011 ◽  
Vol 687 ◽  
pp. 138-143 ◽  
Author(s):  
Gui Sheng Gan ◽  
Lei Zhang ◽  
Yi Lu ◽  
Bin Yang
Keyword(s):  
Thermal Expansion ◽  
Physical Properties ◽  
Coefficient Of Thermal Expansion ◽  
Hot Isostatic Pressing ◽  
Spray Forming ◽  
Alloy Matrix ◽  
Primary Si ◽  
Thermo Physical Properties ◽  
Scanning Electron

2wt.%TiB2/Si-30Al composite was prepared by in-situ reaction and spray forming first and then by hot isostatic pressing (HIP). The microstructure and thermo-physical properties of the composite were investigated by means of scanning electron microscopy, and thermal expansion analyzer respectively. The results show that the microstructure of the TiB2/Si-30Al composite consists of a continuous network of primary Si (~35μm), interpenetrating secondary Al phase, and fine TiB2particles (1~2μm). The TiB2particles were uniformly distributed in the Si-30Al alloy matrix. After HIP, the pores in the TiB2/Si-30Al composite were almost eliminated, and the relative density of the composite was up to 98.9%. The 2wt.%TiB2/Si-30Al composite after the HIP exhibits good thermo-physical properties, including lower coefficient of thermal expansion (CTE) (6.6´10-6×K-1) and higher thermal conductivity (84 W×m-1×K-1).

In Situ Testing and Analysis of Thermal Properties of the Ground Formation in Jiangsu, China

2014 ◽  
Vol 933 ◽  
pp. 477-481
Author(s):  
Shuai Chen
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Resistance ◽  
Thermal Response ◽  
Geological Structure ◽  
Ground Source ◽  
In Situ Conditions ◽  
Thermal Conductivity Λ

Ground source heat pump (GSHP) systems exchange heat with the ground, often through a closed-loop, vertical, borehole heat exchanger (BHE). The performance of the BHE depends on the thermal properties of the ground formation, as well as soil or backfill in the borehole. The design and economic probability of GSHP systems need the thermal conductivity of geological structure and thermal resistance of BHE. Thermal response test (TRT) method allows the in-situ determination of the thermal conductivity (λ) of the ground formation in the vicinity of a BHE, as well as the effective thermal resistance (Rb) of this latter. Thermal properties measured in laboratory experiments do not comply with data of in-situ conditions. The present article describes the results of thermal properties of the BHE whose depth is 100m in Yancheng City, Jiangsu Province, China. As shown in these results, λ and Rb of borehole are determined as 1.84(W·m-1·K-1) and 0.121 (m·K·W-1) respectively.

scholarly journals Method for determining the thermal conductivity of in situ formation rock using drilling cuttings

AIP Advances ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 065015
Author(s):  
Fu Yi ◽  
Xupeng Qi ◽  
Xuexin Zheng ◽  
Huize Yu ◽  
Wenming Bai ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
In Situ Formation

Synergistic effect of phase structures and in situ sintering of silver fillers on thermal conductivity of epoxy/polyethersulphone/silver filler composites

Polymer ◽  
2021 ◽  
pp. 123726
Author(s):  
Hajime Kishi ◽  
Takashi Saruwatari ◽  
Takemasa Mototsuka ◽  
Sanae Tanaka ◽  
Takeshi Kakibe ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Synergistic Effect ◽  
Phase Structures

scholarly journals Improvement of mechanical properties of HfB2-based composites by incorporating in situ SiC reinforcement through pressureless sintering

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Ghadami ◽  
E. Taheri-Nassaj ◽  
H. R. Baharvandi ◽  
F. Ghadami
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Relative Density ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Vacuum Atmosphere ◽  
Sic Reinforcement ◽  
Microstructural Studies ◽  
Composite Samples

AbstractHfB2, Si, and activated carbon powders were selected to fabricate 0–30 vol% SiC reinforced HfB2-based composite. Pressureless sintering process was performed at 2050 °C for 4 h under a vacuum atmosphere. Microstructural studies revealed that in situ SiC reinforcement was formed and distributed in the composite according to the following reaction: Si + C = SiC. A maximum relative density of 98% was measured for the 20 vol% SiC containing HfB2 composite. Mechanical investigations showed that the hardness and the fracture toughness of these composites were increased and reached up to 21.2 GPa for HfB2-30 vol% SiC and 4.9 MPa.m1/2 for HfB2-20 vol% SiC, respectively. Results showed that alpha-SiC reinforcements were created jagged, irregular, and elongated in shape which were in situ formed between HfB2 grains and filled the porosities. Formation of alpha-SiC contributed to improving the relative density and mechanical properties of the composite samples. By increasing SiC content, an enhanced trend of thermal conductivity was observed as well as a reduced trend for electrical conductivity.

In-situ synthesized nanocrystalline UO2/SiC composite with superior thermal conductivity

2021 ◽  
Author(s):  
Dezhi Zhang ◽  
Yingru Li ◽  
Zhenliang Yang ◽  
Bingqing Li ◽  
Zhiyi Wang ◽  
...  
Keyword(s):  
Thermal Conductivity

scholarly journals Research on Thermal Stability and Properties of Ca3ZrSi2O9 as Potential T/EBC Materials

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 583
Author(s):  
Yangyang Pan ◽  
Bo Liang ◽  
Yaran Niu ◽  
Dijuan Han ◽  
Dongdong Liu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Fracture Toughness ◽  
Room Temperature ◽  
Coefficient Of Thermal Expansion ◽  
Atmospheric Plasma ◽  
Thermal Barrier ◽  
Mechanical And Thermal Properties ◽  
Self Healing ◽  
Barrier Coating

In this study, a new coating material for thermal barrier coating (TBC) or environment barrier coating (EBC) application, Ca3ZrSi2O9 (CZSO), was synthesized and prepared by atmospheric plasma spray (APS) technology. The evolution of the phases and microstructures of the coatings with different thermal-aged were characterized by XRD, XRF, EDS and SEM, respectively. The thermal stability was measured by TG-DTA and DSC. The mechanical and thermal properties, including Vickers hardness (HV), fracture toughness (KIC), thermal conductivity () and coefficient of thermal expansion (CTE) were focused on. It was found that the as-sprayed CZSO coating contained amorphous phase. Crystalline transformation happened at 900–960 ∘C and no mass changes took place from room temperature (RT) to 1300 ∘C. The phenomena of microcrack self-healing and composition uniformity were observed during thermal aging. The of coating was very low at about 0.57–0.80 Wm−1K−1 in 200–1200 ∘C. The combined properties indicated that the CZSO coating might be a potential T/EBC material.

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