Carbon Foam with High Strength and High Thermal Conductivity Doped by Nano-Titanium

A carbon foam with high strength and high thermal conductivity was prepared through the incorporation of nano-titanium particle into mesophase pitch precursor. Results show that titanium act as catalysts to accelerate the graphitization of carbon, promote more perfect and larger crystallites and enhance the conductive and mechanical properties. Test results reveal that titanium doped carbon foam (TDCF) has excellent compressive strength and high thermal conductivity, with highest values reaching 29.6 MPa and 117.8 Wm-1 K-1 for a titanium concentration of 12 wt% in the precursor materials. More compact struts and cell walls stacked by more uniform were observed by scanning electron microscope in carbon foam. Correlation between the content of dopant and the properties and microstructure of TDCF was discussed.

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High Strength and High Thermal Conductivity Carbon Foam Reinforced with Graphite Nanoparticles

Cellular Polymers ◽

10.1177/026248930702600502 ◽

2007 ◽

Vol 26 (5) ◽

pp. 305-312 ◽

Cited By ~ 2

Author(s):

Yong Wang ◽

Zhi Xu ◽

Qingqing An ◽

Yimin Wang

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

High Pressure ◽

Coal Tar ◽

High Strength ◽

Carbon Foam ◽

High Thermal Conductivity ◽

Mesophase Pitch ◽

High Pressure And Temperature ◽

Graphite Nanoparticles

A novel carbon foam with high strength and high thermal conductivity was prepared through the incorporation of graphite nanoparticles into coal tar based mesophase pitch precursor. Carbon foam was obtained after carbonization and graphitication of pitch foam formed by the pyrolysis of coal tar based mesophase pitch mixed with graphite nanoparticles in a high pressure and temperature chamber. The foam had possessed high strength and exceptional high thermal conductivity. SEM observation showed that less micro cracking appeared on the cell wall of foam by the addition of graphite nanoparticles. The test of thermal conductivity and mechanical properties shows that the thermal conductivity of modified carbon foam could reach 195 W/m.K. The mechanical properties were improved markedly, and compressive strength was increased from 2 MPa to 18.8 MPa when the additive amount of graphite nanoparticles was 8%.

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Mechanical Properties of Microscale Graphitic Carbon Foam Ligaments and Nodes

Volume 11: Mechanics of Solids, Structures and Fluids ◽

10.1115/imece2009-12582 ◽

2009 ◽

Author(s):

S. Ganguli ◽

A. K. Roy ◽

R. Wheeler

Keyword(s):

Thermal Conductivity ◽

Thermal Management ◽

Thermal Protection ◽

Solid Phase ◽

Coefficient Of Thermal Expansion ◽

Carbon Foam ◽

High Thermal Conductivity ◽

Uniform Size ◽

Open Cell ◽

Carbon Foams

Carbon foam is recognized as having the greatest potential to replacement for metal fins in thermal management systems such as heat exchangers, space radiators, and thermal protection systems [1–5]. Carbon foam refers to a broad class of materials that include reticulated glassy, carbon and graphitic foams that are generally open-cell or mostly open-cell. They can be tailored to have low or high thermal conductivity with a low coefficient of thermal expansion and density. These foams have high modulus but low compression and tensile strength. Among the carbon foams, the graphitic foam offers superior thermal management properties such as high thermal conductivity. Graphitic foams are made of a network of spheroidal shell segments. Each cell has thin, stretched ligaments in the walls that are joined at the nodes or junctions. The parallel arrangement of graphene planes in the ligaments confers highly anisotropic properties to the walls of the graphitic foams. The graphene planes tend to be oriented with the plane of the ligaments but become disrupted at the junctions (nodes) of the walls. Since conduction is highest along parallel graphene planes, the thermal conductivity is highest in the plane of the ligaments or struts, and much lower in the direction transverse to the plane of these ligaments. In a previous study [6] extensive mechanical and thermal property characterization of carbon foams from Kopper Inc. (L1) and POCO Graphite, Inc. (P1) were reported. These foams were graphitic ones that are expected to have high thermal conductivity. Figure 1 shows sections of light microscopy images of the three foams of four foams. The most important thing to notice is that the images were not at the same magnification. The large cells in the GrafTech foam have an average diameter of only ∼100 μm but have a bimodal distribution cells with many small closed-cells few micrometers in diameter. Changes in density in the GrafTech foam was accompanied by a change in the large cells’ diameter — larger diameter giving greater porosity and lower density without changing the smaller cells’ sizes that filled the solid phase between the larger bubbles. The POCO foam has a fairly uniform size cell distribution of a few hundred micrometers. The Koppers’ foams show larger cells yet with the left (“L” precursor) having a uniform size while the right-hand (“D” precursor) is a less uniform and lower porosity.

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A Study on the Thermal Properties of High-Strength Concrete Containing CBA Fine Aggregates

Materials ◽

10.3390/ma13071493 ◽

2020 ◽

Vol 13 (7) ◽

pp. 1493 ◽

Cited By ~ 1

Author(s):

In-Hwan Yang ◽

Jihun Park

Keyword(s):

Thermal Conductivity ◽

Compressive Strength ◽

Thermal Properties ◽

Ultrasonic Velocity ◽

High Strength Concrete ◽

High Strength ◽

Unit Weight ◽

Test Results ◽

Strength Concrete ◽

Fine Aggregates

The thermal conductivity of concrete is a key factor for efficient energy consumption in concrete buildings because thermal conductivity plays a significant role in heat transfer through concrete walls. This study investigated the effects of replacing fine aggregates with coal bottom ash (CBA) and the influence of curing age on the thermal properties of high-strength concrete with a compressive strength exceeding 60 MPa. The different CBA aggregate contents included 25%, 50%, 75%, and 100%, and different curing ages included 28 and 56 days. For concrete containing CBA fine aggregate, the thermal and mechanical properties, including the unit weight, thermal conductivity, compressive strength, and ultrasonic velocity, were measured. The experimental results reveal that the unit weight and thermal conductivity of the CBA concrete were highly dependent on the CBA content. The unit weight, thermal conductivity, and compressive strength of the concrete decreased as the CBA content increased. Relationships between the thermal conductivity and the unit weight, thermal conductivity and compressive strength of the CBA concrete were proposed in the form of exponential functions. The equations proposed in this study provided predictions that were in good agreement with the test results. In addition, the test results show that there was an approximately linear relationship between the thermal conductivity and ultrasonic velocity of the CBA concrete.

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Simultaneous achievement of high thermal conductivity, high strength and formability in Mg-Zn-Ca-Zr sheet alloy

Materials Research Letters ◽

10.1080/21663831.2020.1759718 ◽

2020 ◽

Vol 8 (9) ◽

pp. 335-340 ◽

Cited By ~ 1

Author(s):

Z. H. Li ◽

T. T. Sasaki ◽

T. Shiroyama ◽

A. Miura ◽

K. Uchida ◽

...

Keyword(s):

Thermal Conductivity ◽

High Strength ◽

High Thermal Conductivity ◽

Sheet Alloy

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Improvement in mechanical properties in AlN-h-BN composites with high thermal conductivity

Journal of Advanced Ceramics ◽

10.1007/s40145-021-0506-0 ◽

2021 ◽

Author(s):

Zetan Liu ◽

Shiqiang Zhao ◽

Tian Yang ◽

Ji Zhou

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Hexagonal Boron Nitride ◽

Relative Dielectric Constant ◽

High Strength ◽

Secondary Phase ◽

High Thermal Conductivity ◽

Raw Material ◽

Composite Ceramics ◽

Powder Particles

AbstractIt is possible to improve the machinability of aluminum nitride-hexagonal boron nitride (AlN-h-BN) ceramics while maintaining high strength and high thermal conductivity. The composite ceramics with 0–30 wt% BN as secondary phase were prepared by hot pressed sintering, using yttrium oxide (Y2O3) as sintering aid. The phase composition, density, microstructure, mechanical properties, thermal conductivity, and dielectric properties were investigated. The sintering additives were favorable to purify the grain boundaries and improve densification, reacting with oxide impurities on the surface of raw material powder particles. The optimum BN content improved the flexural strength and fracture toughness of composite ceramics with 475 MPa and 4.86 MPa·m1/2, respectively. With increasing the amount of BN, the thermal conductivity and hardness of composites gradually decreased, but the minimum value of thermal conductivity was still 85.6 W·m−1·K−1. The relative dielectric constant and dielectric loss tangent of the samples ranged from 6.8 to 8.3 and from 2.4 × 10−3 to 6.4 × 10−3, respectively, in 22–26 GHz.

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Graphene oxide-loaded shortening as an environmentally friendly heat transfer fluid with high thermal conductivity

Thermal Science ◽

10.2298/tsci150312199v ◽

2017 ◽

Vol 21 (5) ◽

pp. 2247-2254

Author(s):

Thammasit Vongsetskul ◽

Peeranut Prakulpawong ◽

Panmanas Sirisomboon ◽

Jonggol Tantirungrotechai ◽

Chanasuk Surasit ◽

...

Keyword(s):

Heat Transfer ◽

Electron Microscopy ◽

Thermal Conductivity ◽

Graphene Oxide ◽

Environmentally Friendly ◽

High Thermal Conductivity ◽

Chemical Degradation ◽

Heat Transfer Fluid ◽

Increasing Temperature ◽

Scanning Electron

Graphene oxide-loaded shortening (GOS), an environmentally friendly heat transfer fluid with high thermal conductivity, was successfully prepared by mixing graphene oxide (GO) with a shortening. Scanning electron microscopy revealed that GO particles, prepared by the modified Hummer?s method, dispersed well in the shortening. In addition, the latent heat of GOS decreased while their viscosity and thermal conductivity increased with increasing the amount of loaded GO. The thermal conductivity of the GOS with 4% GO was higher than that of pure shortening of ca. three times, from 0.1751 to 0.6022 W/mK, and increased with increasing temperature. The GOS started to be degraded at ca. 360?C. After being heated and cooled at 100?C for 100 cycles, its viscosity slightly decreased and no chemical degradation was observed. Therefore, the prepared GOS is potentially used as environmentally friendly heat transfer fluid at high temperature.

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