Graphite bridge

Plugs for graphite bridge initiators are made by molding the plastic about a twisted pair of enameled wires, and thea grinding the surface clean, bis ieaves a plastic surface with two metal islands separated by twice the thickness of the enamel. A droplet of colloidal suspension of graphite in water is applied over the point of closest approach of these islands to dry. Since both resistance... 

Refs 1) W.M. Slie, "An Insensitive Substitute for Graphite Bridge Detonators for Laboratory Evaluation of Fuze Explosive Trains , NOL, NAVORD Report 4512 (Feb 1957) 2) Anon, Engineering Design... 

Figure 3. Lead azide in electric detonators [1] (a) bridge wire (b) high temperature (c) graphite bridge.

Mote stable catalysts ate obtained by using fluorinated graphite or fluorinated alumina as backbones, and Lewis acid halides, such as SbF, TaF, and NbF, which have a relatively low vapor pressure. These Lewis acids ate attached to the fluorinated soHd supports through fluorine bridging. They show high reactivity in Friedel-Crafts type reactions including the isomerization of straight-chain alkanes such as / -hexane. 

G lv nic Corrosion. Galvanic corrosion is an electrochemical process with four fundamental requirements (/) an anode (magnesium), 2) a cathode (steel, brass, or graphite component), (J) direct anode to cathode electrical contact, and (4) an electrolyte bridge at the anode and cathode interface, eg, salt water bridging the adjacent surfaces of steel and magnesium components. If any one of these is lacking, the process does not occur (133,134). 

A key factor in the suitabihty of cokes for graphite production is their isotropy as determined by the coefficient of thermal expansion. After the calcined coke was manufactured into graphite, the axial CTE values of the graphite test bars were determined using a capacitance bridge method over a temperature range of 25 to 100°C. The results are summarized in Table 24. Also included in the table are bulk density measurement of calcined cokes and the resistivity values of their graphites. 

Potassium graphite reduction of the dichloro precursors under an atmosphere of N2 in THF according to Scheme 101 allowed access to new families of Group 4 bimetallic "side-on-bridged" dinitrogen complexes... 

Figure 6 Steady state rotating ring-disk voltammograms of (A) compound (42) (B) compound (43) and (C) a Ru-bridged polymer of (43) each adsorbed to a graphite working electrode. Disk current shows reduction of 02 while ring current reveals the presence of H202 simultaneously reoxidised at the ring anode poised at +1.0 V (reproduced with permission of the American Chemical Society from Acc. Chem. Res., 1997, 30, 437-444).

The most thoroughly studied mixed S jA-ligand is pyridine-2-thiolate because of its versatile coordination modes. The compound [Ag(SPy)] has a graphite-like array of silver(I) ions and has a semiconductor behavior. The PyS ligand acts as a fi3-N,S,S bridge. [Ag5(SPy)(HSPy)BF4] has a layered structure with the coordination modes of PyS showed in Figure 14.1 04... 

The idea of electronic conductivity in the crystals of this cluster is stimulated by the metallic reflectance of the crystals. A potential conductivity is expected to be anisotropic because of the anisotropic order of the clusters inside the crystal. As a consequence, the electric resistance is expected to be smaller in the direction of the tubes than in the vertical direction where there is no graphite-like bridging between the clusters. 

Several strategies based on porphyrin derivatives have been developed to reach this objective. The first approach involves the utilization of dimeric cofacial metallic porphyrins adsorbed on the surface of an edge-plane graphite (EPG) electrode.18 An 02 molecule was expected to be coordinated to form a fi-02 bridge between the two metal centers allowing subsequent scission of the O O bond by reductive activation, while the dimeric structure acts as a four-electron reservoir. 

It has been recently demonstrated that the simplest of the cobalt porphyrins (Co porphine) adsorbed on a pyrolytic graphite electrode is also an efficient electrocatalyst for reduction of 02 into 1120.376 The catalytic activity was attributed to the spontaneous aggregation of the complex on the electrode surface to produce a structure in which the cobalt-cobalt separation is small enough to bridge and activate 02 molecules. The stability of the catalyst is quite poor and largely improved by using porphyrin rings with mew-substitu-tion.377-380 Flowever, as the size of the mew-substituents increases the four-electron reduction efficiency decreases. 

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