Composites based on thermally hyper-conductive vapor grown carbon fiber

1995 ◽  
Vol 10 (6) ◽  
pp. 1478-1484 ◽  
Author(s):  
Jyh-Ming Ting ◽  
Max L. Lake ◽  
David R. Duffy

Aluminum matrix composites and carbon/carbon composites based on vapor grown carbon fiber (VGCF) were fabricated for analysis of thermophysical properties. Due to the highly graphitic nature of VGCF, the resulting composites exhibit values of thermal conductivity that have not been achieved by using any other carbon fibers, and thus represent new materials for thermal management in applications such as packaging for high-power, high-density electronic devices. In the aluminum matrix VGCF composites, a thermal conductivity of 642 W/m-K was obtained by using a VGCF loading of only 36.5 vol.%. For VGCF/C composites, thermal conductivity of 910 W/m-K has been observed, a value which is more than a factor of two higher than that of copper. Based on the observed thermal conductivity of VGCF/Al composites and VGCF/C composites, the room temperature thermal conductivity of VGCF in the composite was calculated to be 1460 W/m-K and 1600 W/m-K, respectively.

1995 ◽  
Vol 383 ◽  
Author(s):  
Jyh-Ming Ting

ABSTRACTIn contrast to the form in which other carbon fibers are produced, vapor grown carbon fiber (VGCF) is produced from gas phase precursors in the form of individual fibers of discrete lengths. VGCF can be harvested as a mat of semi-aligned, semicontinuous fibers, with occasional fiber branching and curling. The use of VGCF mats as reinforcement result in composites which exhibit unique microstructure and physical properties that are not observed in other types of carbon composites. This paper describes the processing of VGCF mats reinforced carbon composites, and its unique microstructure and properties. Utilization of fiber tensile properties, as well as thermal conductivity, in the composites is discussed. Comparison of experimental results from various VGCF composites to theory indicates that mechanical properties are more strongly affected by characteristics of VGCF mat than are thermal conductivity. The implications of this relationship favors applications for thermal management where structural demands are less stringent.


2017 ◽  
Vol 62 (2) ◽  
pp. 1267-1270
Author(s):  
D.-H. Kim ◽  
T.-J. Kim ◽  
S.-G. Lim

AbstractIn this study, mechanical properties and microstructures of extruded aluminum matrix composites were investigated. The composite materials were manufactured by two step methods: powder metallurgy (mixture of aluminum powder and carbon fiber using a turbular mixer, pressing of mixed aluminum powder and carbon fiber using a cold isostatic pressing) and hot extrusion of pressed aluminum powder and carbon fiber. For the mixing of Al powder and carbon fibers, aluminum powder was used as a powder with an average particle size of 30 micrometer and the addition of the carbon fibers was 50% of volume. In order to make mixing easier, it was mixed under an optimal condition of turbular mixer with a rotational speed of 60 rpm and time of 1800s. The process of the hot-extrusion was heated at 450°C for 1 hour. Then, it was hot-extruded with a condition of extrusion ratio of 19 and ram speed of 2 mm/s. The microstructural analysis of extruded aluminum matrix composites bars and semi-solid casted alloys were carried out with the optical microscope, scanning electron microscope and X-ray diffraction. Its mechanical properties were evaluated by Vickers hardness and tensile test.


1998 ◽  
Vol 551 ◽  
Author(s):  
J.-M. Ting ◽  
C. Tang ◽  
P. Lake

AbstractAluminum matrix composites reinforced with high thermal conductivity vapor grown carbon fiber (VGCF) were developed for improved thermal efficiencies in electronic devices. The carbon fiber was heat treated to increase its thermal conductivity. Various aluminum matrix composites were fabricated by the densification of fiber preforms using a pressure casting technique. Uniformity of the density was examined using optical microscopy. A scanning electron microscope equipped with a microprobe was utilized to examine the mechanical integrity of the composite. Mechanical properties, including tension, compression and flexural properties, were measured. While the results of the mechanical property measurements indicate moderate values, the composite exhibited remarkable thermal conductivity that reached 642 W/m.K, three times that of aluminum, at a fiber volume fraction of 36.5%, following closely the rule of mixture.


2011 ◽  
Vol 686 ◽  
pp. 758-764 ◽  
Author(s):  
Xiao Ming Sui ◽  
Xi Liang Xu ◽  
Xiao Meng Zheng ◽  
Guang Zhi Xu ◽  
Qiang Wang

Driven by the increasing requirements from aircraft producers, aluminium alloy matrix composites with carbon fiber reinforcement have been largely used in the modern industry. The method of traditional preparation of carbon fiber reinforced aluminum matrix composites is not only high cost and complex to produce but also difficult to apply in the civilian. The present paper focuses on exploratory study on the preparation of carbon-fiber- reinforced aluminum composites, the intensifying material is continuous long carbon fiber. In order to avoid any interfacial reactions in the carbon fiber reinforced composites, the carbon fibers were coated with copper. We made The tensile samples were made by using the mould, the tensile properties determined, the strengthening mechanism studied, and the carbon fiber in the matrix observed with the microscope.


1993 ◽  
Vol 323 ◽  
Author(s):  
Shy-Wen Lai ◽  
D. D. L. Chung

AbstractAluminum-matrix composites containing AIN or SiC particles were fabricated by vacuum infiltration of liquid aluminum into a porous particulate preform under an argon pressure of up to 41 MPa. Al/AIN was superior to Al/SiC in thermal conductivity. At 59 vol.% AIN, Al/AlN had a thermal conductivity of 157 W/m. °C and a thermal expansion coefficient of 9.8 × 10−-6°C−1 (35–100 °C). Al/AlN had similar tensile strength and higher ductility compared to Al/SiC of a similar reinforcement volume fraction at room temperature, but exhibited higher tensile strength and higher ductility at 300–400°C. The ductility of Al/AlN increased with increasing temperature from 22 to 400°C, while that of Al/SiC did not change with temperature. The superior high temperature resistance of Al/AlN is attributed to the lack of a reaction between Al and AIN, in contrast to the reaction between Al and SiC in AI/SiC.


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