Thermal conductivity and electrical resistivity of poco grade AXF-Q1 graphite to 3300° K

Bapat, Saurabh; Nickel, H.

doi:10.1016/0008-6223(73)90073-0

Cited by 35 publications

(4 citation statements)

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“…$400°C is consistent with those for typical near-isotropic carbon materials [13], but is very different from those for typical CVD SiC. Therefore, one can conclude that the through-thickness conduction in the low temperature regime is primarily through the interphase.…”

Section: Discussionsupporting

confidence: 72%

DC electrical conductivity of silicon carbide ceramics and composites for flow channel insert applications

Katoh

Kondo

Snead

2009

Journal of Nuclear Materials

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Section: Discussionsupporting

confidence: 72%

DC electrical conductivity of silicon carbide ceramics and composites for flow channel insert applications

Katoh

Kondo

Snead

2009

Journal of Nuclear Materials

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“…The resistivity and thermal conductivity of potential feedstocks vary considerably, and at a specified diameter, the corresponding It and mt also vary over fairly wide limits. Figure 3 shows mt plotted against anode radius for graphite and a carbon having properties similar to a by extrapolating the high-temperature experimental data of Bapat (1973) and Bapat and Nickel (1973) and are thought to be typical of commercial graphites. Because graphite has a lower resistivity and higher thermal conductivity than other carbons, It is relatively high, and allowing for minor variations in the properties of different commercial products, mt for graphite is thought to be the upper limit to the rate of vaporization of a carbon feedstock from a single anode of specified diameter in a highintensity arc reactor.…”

Section: Resultsmentioning

confidence: 99%

Limit to erosion rate in a high-current carbon arc

Davies¹,

Abrahamson²

1983

Ind. Eng. Chem. Proc. Des. Dev.

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A mathematical madel of the thermal processes in an anode has shown that there is a maximum rate at which a specified feedstock can be vaporized in a hlgh-intensity arc reactor. For a hlghquaiity graphite anode this is about 7.8 g s-', and this is thought to be the maximum carbon vaporization rate for any pure carbon feedstock. Experimental results support the use of the model. The energy requirements for carbon vaporization are discussed. IntroductionA high-intensity carbon arc can vaporize very refractory electrode material, and because of this it has been considered for a number of diverse processing applications. For example, acetylene has been produced from solid carbon and hydrogen (Baddour and Iwasyk, 1962;Baddour and Blanchet, 1964; Abrahamson, 1971; Ward, 1974); a high-intensity arc reactor has been used in the carbothermic reduction of rhodonite (Harris et al., 1959); several arc processes for reducing refractory ores have been proposed and patented (for example, Sheer and Korman, 1952, 1962; and a high-intensity arc reactor has been used in research on the production of particulate boron carbide (Wickens, 1976).The scale of the work reviewed above is small, and we have not found any examples of production plants using high-intensity arc reactors. Satisfactory conversions of feedstock have been reported, but the energy required to make unit mass of product was in all cases high and often several times that needed by alternative process routes to the same product. For instance, Baddour and Iwasyk (1962) used 6.35 mm diameter anodes at feed rates up to 0.15 g s-l. Up to 52% of the carbon feedstock was converted into hydrocarbons, mainly acetylene. The specific energy requirement for carbon vaporization in an electric arc, (SER),, estimated from the published results, decreased with increasing ablation rate, and was about 26 kWh kg-l when the ablation rate was 0.15 g s-l. At a carbon conversion of 50%, this is 48 kWh kg-' of acetylene. Industrially, the production of one kilogram of acetylene from gaseous and liquid feedstocks requires about 9.9 kwh (Lobo, 1961). Harris et al. (1959) used 50 mm diameter composite anodes containing 1618% carbon and 82-84% rhodonite and decomposed the rhodonite in the anode feedstock to MnO and SiOz. The feed rate was only 2.5 g s-l and the energy required was 8.5 kwh kg-' of product, which is about six times as much energy as required by an alternative process that melted the rhodonite in a conventional arc furnace (Fuller et al., 1964). Expressed in terms of the carbon in the feed, energy consumed was 34.5 kWh kg-l of carbon vaporized, i.e. (SER), = 34.5 kwh kg-'.Though some authors have expressed optimism that performance could be improved by increasing the scale of operation, low throughput and low energy efficiency appear to be inherent properties of high intensity arc processing, and increase in scale does not bring much benefit. We have modeled the behavior of a carbon anode in a highintensity arc reactor and have found that there is a max-* 01964305f83f 1 l22-0226$0...

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“…At high temperatures after passing a maximum, ln κ tends to decrease (1/ T dependence) with increasing temperature . In Figure , temperature dependence of κ is shown for isotropic graphite, in comparison with the κ calculated by the formula 1/( AT + B ), with A = 1.0036 × 10 −5 mW −1 and B = 0.9194 × 10 −2 mK W −1 . The κ ‐values and the temperature at which κ reaches maximum depended strongly on the preparation conditions of graphite.…”

Section: Materials With High Thermal Conductivitymentioning

confidence: 91%

“…In Figure , temperature dependence of κ for pyrolytic graphites annealed at different temperatures, which have different degrees of orientation and different crystallinity (degree of graphitization), is reproduced by comparing for natural graphite . At high temperatures after passing a maximum, ln κ tends to decrease (1/ T dependence) with increasing temperature . In Figure , temperature dependence of κ is shown for isotropic graphite, in comparison with the κ calculated by the formula 1/( AT + B ), with A = 1.0036 × 10 −5 mW −1 and B = 0.9194 × 10 −2 mK W −1 .…”

Section: Materials With High Thermal Conductivitymentioning

confidence: 92%

Thermal Management Material: Graphite

Kaburagi²,

2014

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Graphite has pronounced anisotropy in its properties. Thermal conductivity of graphite crystal is extremely high along its layer plane, as high as 2000 Wm À1 K À1 , much higher than metals, and very low across its layer plane, as low as 7 Wm À1 K À1 . This anisotropy gives high possibility for graphite as thermal management materials. Here, graphite membranes with high thermal conductivity along the surface for heat dissipation and with low conductivity perpendicular to the surface for heat insulation, in addition to graphite foams as container of phase change materials for heat energy storage, are reviewed, particularly referring to the preparations of various graphite materials. Thermal conductivity of diamond crystal is also high, 2500 Wm À1 K À1 , but it is very sensitive for structural defects, but that of graphitic materials is less sensitive for structural defects, suggesting that the latter is more practical for thermal management than the former.(along the layer plane) as %2000 Wm À1 K À1 , [1] much higher than metals, such as Cu and Ag, but very small k RT along the c-axis (perpendicular to the layer plane) as around 6-9 Wm À1 K À1[2] : graphite crystal can be highly conductive along the layer and be highly insulating perpendicular to the layer. This pronounced anisotropy is due to graphite structure, graphite layer consisting of strong s bonding, and parallel stacking of these layers by van der Waals bonding due to the interaction between p-electron clouds on neighboring layers. Diamond crystal, which consists of carbon atoms using sp 3 CÀ ÀC bonding, is isotropic and has the highest value of k RT in solids as %2200 Wm À1 K À1 . [3] Highly graphitized carbon materials exhibit very high thermal conductivities. A highly-oriented pyrolytic graphite (HOPG) is reported to have k RT of 1950 Wm À1 K À1 . [1,4] Recently, graphite films with high thermal conductivity have become commercially available for dissipating heat from electronic devices containing integrated circuits, such as personal computers and mobile phones. [5] The k RT of the commercially available graphite films is reported to be more than 1600 Wm À1 K À1 , more than four times higher than the values of Ag, which is known to have the highest k RT among metals. Carbon/carbon composites prepared from natural graphite flakes by using mesophase pitch as binder, followed by heat treatment at high temperatures, gives k RT of about 650 Wm À1 K À1 , higher than Ag. In order to develop practical materials having k high enough, the preparation of highly oriented and highly crystallized graphite is essential. Flexible graphite sheets prepared from natural graphite via [*] Prof. M. InagakiProfessor Emeritus

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Thermal conductivity and electrical resistivity of poco grade AXF-Q1 graphite to 3300° K

Cited by 35 publications

References 1 publication

DC electrical conductivity of silicon carbide ceramics and composites for flow channel insert applications

DC electrical conductivity of silicon carbide ceramics and composites for flow channel insert applications

Limit to erosion rate in a high-current carbon arc

Thermal Management Material: Graphite

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