Advanced Composites for LIDAR Applications

2005 ◽  
Vol 883 ◽  
Author(s):  
Witold Kowbel ◽  
Jim Withers ◽  
Rigel Woida
Keyword(s):  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Composite Material ◽  
Thermal Management ◽  
Laser Diodes ◽  
Current Generation ◽  
New Approach ◽  
Advanced Composites ◽  
Novel Technology ◽  
Graphite Foam

AbstractThe current generation of laser diodes suffers from poor thermal management. Typically, Cu-W is used as a submount material. Although it offers a good CTE match with GaAs, thermal conductivity is very limited (160 W/mK). A new approach to improving the thermal management of laser diodes was developed involving the use of hybrid CC/graphite foam composites.We also have a novel technology developed for LIDAR optical structures consisting of SiC-SiC composite material which exhibits excellent fracture toughness and homogeneous CTE.

Thermal Characteristics of Graphite Foam Thermosyphon for Electronics Cooling

2003 ◽  
Author(s):  
Hongkoo Roh ◽  
Jungho Kim ◽  
Paul J. Boudreaux
Keyword(s):  
Thermal Conductivity ◽  
Thermal Management ◽  
Thermal Characteristics ◽  
Electronics Cooling ◽  
Liquid Level ◽  
Working Fluid ◽  
Low Density ◽  
Thermal Management Of Electronics ◽  
Graphite Foam ◽  
Density Results

Graphite foams consist of a network of interconnected graphite ligaments and are beginning to be applied to thermal management of electronics. The thermal conductivity of the bulk graphite foam is similar to aluminum, but graphite foam has one-fifth the density of aluminum. This combination of high thermal conductivity and low density results in a specific thermal conductivity about five times higher than that of aluminum, allowing heat to rapidly propagate into the foam. This heat is spread out over the very large surface area within the foam, enabling large amounts of energy to be transferred with relatively low temperature difference. For the purpose of graphite foam thermosyphon design in electronics cooling, various effects such as graphite foam geometry, sub-cooling, working fluid effect, and liquid level were investigated in this study. The best thermal performance was achieved with the large graphite foam, working fluid with the lowest boiling point, a liquid level with the exact height of the graphite foam, and at the lowest sub-cooling temperature.

BRUSH ALLOY 390

Alloy Digest ◽  
2004 ◽  
Vol 53 (3) ◽  
Keyword(s):  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Thermal Management ◽  
Elevated Temperatures ◽  
Electrical Contact ◽  
High Strength ◽  
Harsh Environments ◽  
Relaxation Resistance ◽  
Temperature Performance ◽  
Higher Power

Abstract Brush Alloy 390 was specifically designed for high-power applications and provides a combination of high strength and high conductivity. Increasing power requirements drive the need for lower conductor resistance to reduce joule heating. This alloy has a high thermal conductivity that is critical to thermal management. Higher power requirements create harsh environments and higher operating temperatures. Alloy 390 provides excellent stress-relaxation resistance at elevated temperatures, which increases electrical contact reliability. This datasheet provides information on composition, physical properties, and elasticity as well as fracture toughness, deformation, and fatigue. It also includes information on high temperature performance. Filing Code: CU-712. Producer or source: Brush Wellman Inc.

Graphite Foam Thermosyphon Evaporator Performance: Parametric Investigation of the Effects of Working Fluid, Liquid Level, and Chamber Pressure

2002 ◽  
Author(s):  
Johnathan S. Coursey ◽  
Hongkoo Roh ◽  
Jungho Kim ◽  
Paul J. Boudreaux
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Thermal Management ◽  
Liquid Level ◽  
Chamber Pressure ◽  
Working Fluid ◽  
Low Density ◽  
Thermal Management Of Electronics ◽  
Graphite Foam ◽  
Density Results

Graphite foams have recently been developed at ORNL and are beginning to be applied to thermal management of electronics. These foams consist of a network of interconnected graphite ligaments whose thermal conductivities are up to five times higher than copper. The thermal conductivity of the bulk graphite foam is similar to aluminum, but graphite foam has one-fifth the density of aluminum. This combination of high thermal conductivity and low density results in a thermal diffusivity about four times higher than that of aluminum, allowing heat to rapidly propagate into the foam. This heat is spread out over the very large surface area within the foam, enabling large amounts of energy to be transferred with relatively low temperature difference. The use of graphite foam as the evaporator of a thermosyphon is investigated due to its potential to transfer large amounts of energy without the need for external pumping. A preliminary optimization of the parameters governing evaporator performance is performed using 2-level factorial design. Performance of the system with both PF-5060 and PF-5050 were examined as well as the effects of liquid level and chamber pressure.

scholarly journals Effect of Liquid Phase Additions on Microstructure and Thermal Properties in Copper and Copper-Diamond Composites

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
A. Rape ◽  
X. Liu ◽  
A. Kulkarni ◽  
J. Singh
Keyword(s):  
Thermal Conductivity ◽  
Liquid Phase ◽  
Thermal Management ◽  
Diamond Particle ◽  
Two Phase ◽  
New Approach ◽  
The Matrix ◽  
Reactive Liquid ◽  
Field Assisted Sintering ◽  
Solid Liquid

This study details a new approach to creating copper-diamond composite materials for thermal management applications by using a two-phase (solid-liquid) approach in powder metallurgy using Field Assisted Sintering Technology (FAST). Silver-copper alloyed powder at eutectic compositions was used as a nonreactive liquid phase while Cu5Si was used as a reactive liquid phase. Microstructure results are reported favorably comparing the additions of a small amount of liquid phase to pure solid state sintering. Additionally, EDX results indicate that the liquid phase material fills gaps at the interface of the matrix and diamond particle resulting in improved microstructure and density. Thermal conductivity results show that liquid phase additions improve the thermal conductivity of composites compared to composites without any liquid phase, but Si additions cause a severe drop in baseline conductivity.

COPPER ALLOY No. 172

Alloy Digest ◽  
1966 ◽  
Vol 15 (6) ◽  
Keyword(s):  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Shear Strength ◽  
Copper Alloy ◽  
Precipitation Hardening ◽  
Heat Treating ◽  
General Corrosion ◽  
Endurance Strength ◽  
Resistance To Wear

Abstract Copper Alloy No. 172 is a precipitation hardening beryllium-copper alloy having high elastic and endurance strength, good electrical and thermal conductivity, excellent resistance to wear, and high resistance to general corrosion. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength as well as fracture toughness and fatigue. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Cu-165. Producer or source: Copper and copper alloy mills.

Lattice Thermal Conductivity Modelling of a Diatomic Nanoscale Material

2020 ◽  
Vol 10 (5) ◽  
pp. 602-609
Author(s):  
Adil H. Awad
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Correction Term ◽  
Nanoscale Material ◽  
New Approach ◽  
Two Samples ◽  
Conductivity Modelling ◽  
Callaway Model

Introduction: A new approach for expressing the lattice thermal conductivity of diatomic nanoscale materials is developed. Methods: The lattice thermal conductivity of two samples of GaAs nanobeam at 4-100K is calculated on the basis of monatomic dispersion relation. Phonons are scattered by nanobeam boundaries, point defects and other phonons via normal and Umklapp processes. Methods: A comparative study of the results of the present analysis and those obtained using Callaway formula is performed. We clearly demonstrate the importance of the utilised scattering mechanisms in lattice thermal conductivity by addressing the separate role of the phonon scattering relaxation rate. The formulas derived from the correction term are also presented, and their difference from Callaway model is evident. Furthermore their percentage contribution is sufficiently small to be neglected in calculating lattice thermal conductivity. Conclusion: Our model is successfully used to correlate the predicted lattice thermal conductivity with that of the experimental observation.

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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