Graphite foams

Carbon—graphite foam is a unique material that has yet to find a place among the various types of commercial specialty graphites. Its low thermal conductivity, mechanical stabiHty over a wide range of temperatures from room temperature to 3000°C, and light weight make it a prime candidate for thermal protection of new, emerging carbon—carbon aerospace reentry vehicles. 

Figure 9.9. Stepwise isotherm of CH4 on graphite foam (open circles) and exfoliated graphite (solid circles) at 77.3 K (reproduced courtesy of Bienfait eta ., 1990).

The preliminary investigation showed that lower pressures result in significantly higher heat fluxes. It s possible to approaeh 50 W/em while maintaining the wall temperature below 85 °C with little optimization. A more eomprehensive parameterization study will be addressed such as pore size, geometry, and other effeets as the limits of graphite foam evaporator performance [34-35]. 

Coursey, J. S., 2003, Performance and Parametric Investigation of a Graphite Foam Thermosyphon Evaporator , MSME Thesis, University of Maryland, College Park... 

Roh, H., Kim, J. and Boudreaux, P.J., 2003, Thermal Characteristic of Graphite Foam Thermosyphon for Electronics Cooling , Proceedings of InterPack03, International Electronic Packaging Technical Conference and Exhibition, July 6-11, 2003, Hawaii, USA (InterPack2003-35002)... 

Determine how graphite foams can be used to enhance the humidification of the fuel cell inlet air. 

Graphite foam (product of Union Carbide) is uncompressed exfoliated graphite obtained at an intermediate stage of the production of Grafoil. The specific area is about 22 m /g. It can be regarded as a uniform powder with a coherence length of 900 100 A [39]. The density of foam is low, about 0.2 g/cm, and thus relatively large sample cells for adsorption studies are necessary. 

The ac heat capacity and vapor pressure isotherm experiments of CO on exfoliated graphite foam [112] allowed the detailed investigation of the narrowing of the commensurate solid-fluid coexistence region as the tricritical point is approached see Fig. 51 for this part of the phase diagram and Fig. 52 for the calorimetric data corresponding to the paths I to VII marked in the phase diagram. The vapor pressure isotherms indicate that the transition... 

Figure 56. Total heat capacity of subtnonolayer CO on graphite foam at a coverage of 0.757 monolayers including the head-tail (dipolar) To, orientational (quadmpolar) Tq, and melting T transitions. The background contribution of the substrate and the sample cell is subtracted from the data. (From Ref. 381.)...

Figure 57. Experimental heat capacity near the head-tail disordering transition of CO on graphite foam at a coverage of 0.75 monolayers, (a) Singular contribution to the total heat capacity, (b) Semilogarithmic plot of the data of (a) as a function of the reduced temperature above (squares) and below (triangles) the transition. Solid lines are fits in terms of the two-dimensional Ising behavior (5.7). (Adapted from Fig. I of Ref. 380.)...

Chao, D., Xia, X., Liu, J., Fan, Z., Ng, C.F., Lin, J., Zhang, H., Shen, ZX, Fan, H.J., 2014. A V205/Conductive-polymer core/shell nanobelt array on three-dimensional graphite foam a high-rate, ultrastable, and freestanding cathode for lithium-ion batteries. Adv. Mater. 26,5794-5800. 

In 2009, Firefly Energy Inc. revealed its Oasis battery, which was developed by Kurt KeUy. This battery is equipped with conventional lead grids as the positive current collector and carbon-graphite foams as the negative current collector. Firefly has named the carbon-graphite technology as 3D technology. Because of the replacement of... 

FIGURE 1.35 Firefly carbon-graphite foam negative current collector. 

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