Resistance specific electrical

Silicone resins are used in applications requiring high thermal or chemical resistance, specific electrical properties, or water repellency, as coatings or as components of paints that withstand harsh conditions such as exposure to high temperature or corrosion in marine environments. 

Electrical Properties. Poly(methyl methacrylate) has specific electrical properties that make it unique (Table 4). The surface resistivity of poly(methyl methacrylate) is higher than that of most plastic materials. Weathering and moisture affect poly(methyl methacrylate) only to a minor degree. High resistance and nontracking characteristics have resulted in its use in high voltage appHcations, and its excellent weather resistance has promoted the use of poly(methyl methacrylates) for outdoor electrical appHcations (22). 

The specific electrical conductivity of dry coals is very low, specific resistance 10 ° - ohm-cm, although it increases with rank. Coal has semiconducting properties. The conductivity tends to increase exponentially with increasing temperatures (4,6). As coals are heated to above ca 600°C the conductivity rises especially rapidly owing to rearrangements in the carbon stmcture, although thermal decomposition contributes somewhat below this temperature. Moisture increases conductivity of coal samples through the water film. 

The specific electrical resistances usually depend on the material and the temperature [31]. For the most important pipe materials these are (in 10 Q cm) ... 

Fig. 3-17 Apparent specific electrical soil resistivity p in the case of two different layers of soil with the resistivities Pi down to a depth of t and p to a depth below t (explanation in the text).

The specific electrical resistance of concrete can be measured by the method described in Section 3.5. Its value depends on the water/cement value, the type of cement (blast furnace, portland cement), the cement content, additives (flue ash), additional materials (polymers), the moisture content, salt content (chloride), the temperature and the age of the concrete. Comparisons are only meaningful for the... 

The cost and economics of cathodic protection depend on a variety of parameters so that general statements on costs are not really possible. In particular, the protection current requirement and the specific electrical resistance of the electrolyte in the surroundings of the object to be protected and the anodes can vary considerably and thus affect the costs. Usually electrochemical protection is particularly economical if the structure can be ensured a long service life, maintained in continuous operation, and if repair costs are very high. As a rough estimate, the installation costs of cathodic protection of uncoated metal structures are about 1 to 2% of the construction costs of the structure, and are 0.1 to 0.2% for coated surfaces. 

The specific electrical soil resistivity is constant in the region under consideration. With short-term interference, the ground short circuit occurs outside the region under consideration. 

Volume resistivity Or specific resistivity of a material, expressed in W/cm. Resistance to electrical current flow through the bulk of an object. 

Epoxy, polyester, phenolic and other resins are used as coatings and linings with or without reinforcement. Glass fiber, silica, carbon and many other materials can be used as filters or reinforcement to produce materials with specific properties of strength, flexibility, wear resistance and electrical conductivity. 

A lomic Atomic Crystal structure Melting point (°C) Density Thermal conduc- tivity (W/m K- ) at 20 C Electrical resistivity Specific heat Thermal expansion Magnetic susceptibility Electrode potential w.r.i. sal calomel (V) z c 2... 

Atomic number Atomic weight Crystal structure Melting Density Thermal Electrical resistivity (at 20°C) Temperature coefficient of resistivity Specific Thermal Standard electrode potential Thermal neutron absorption cross-section. 

Thermal conductivity can be as low as one-eighth that of solid metal in the case of steel 7 W/m°C. The electrical resistance (specific) of copper, zinc and silver is about twice that of the cast metal, and of aluminium as much as five times, depending on spraying conditions. Adhesion in tension should... 

All three of these terms have units of ohms as they are all measures of some form of resistance to electrical flow. The reactance of an inductor is high and comes specifically from the back electromotive force (EMF p. 46) that is generated within the coil. It is, therefore, difficult for AC to pass. The reactance of a capacitor is relatively low but its resistance can be high therefore, direct current (DC) does not pass easily. Reactance does not usually exist by itself as each component in a circuit will generate some resistance to electrical flow. The choice of terms to define total resistance in a circuit is, therefore, resistance or impedance. 

Zone I the E vsj linear curve corresponds to ohmiclosses j in the electrolyte and interface resistances a decrease of the specific electric resistance from 0.3 to 0.15 Dcm gives an increase in the current density j (at 0.7 V) from 0.25 to 0.4 A cm, that is, an increase in the energy efficiency and in the power density of 1.6-fold. 

The specific electrical resistance of an electrolyte solution is defined as the resistance of a cube 1 cm in length and 1 cm2 in cross-sectional area. 

Rhodium. Rhodium is the most commonly plated platinum-group metal. In addition to its decorative uses, rhodium has useful properties for engineering applications. It has good corrosion resistance, stable electrical contact resistance, wear resistance, heat resistance, and good reflectivity. The use of rhodium for engineering purposes is covered by an ASTM specification (128). Typical formulas are shown in Table 15. The metal content is obtained from prepared solutions available from proprietary plating supply companies. Replenishment is required because anodes are not soluble. Rhodium for decorative use may be 0.05—0.13 Jm thick for industrial use, it may be 0.50—5.0 Jm thick. 

Both specific resistance and electrical conductivity depend on temperature. Materials can differ considerably as far as electrical conductivity is concerned and this fact is used to subdivide them, as illustrated in table 11.4.2. 

In this section of the research, the aim is to investigate the optimal composition of the Ni(II)-containing solution as a function of the Ni(II) reduction rate, the total amount of Ni reduced, the fraction of NiS formed and PAN-hbre properties, such as specific electrical resistance. In Fig. 11.2, data are shown for the variation of Ni(II) and rongalite concentration as a function of time and temperature starting from a constant initial Ni(II) concentration, while the initial rongalite concentration was increased. It must be pointed out that in this section of the research, no fibre was immersed in the solution, so the pure kinetic parameters of the reduction reaction of Ni(II) by rongalite is studied. Similar experiments were performed with different initial Ni(II) concentrations. 

A first parameter to be studied is the applied potential difference between anode and cathode. This potential is not necessarily equal to the actual potential difference between the electrodes because ohmic drop contributions decrease the tension applied between the electrodes. Examples are anode polarisation, tension failure, IR-drop or ohmic-drop effects of the electrolyte solution and the specific electrical resistance of the fibres and yarns. This means that relatively high potential differences should be applied (a few volts) in order to obtain an optimal potential difference over the anode and cathode. Figure 11.6 shows the evolution of the measured electrical current between anode and cathode as a function of time for several applied potential differences in three electrolyte solutions. It can be seen that for applied potential differences of less than 6V, an increase in the electrical current is detected for potentials great than 6-8 V, first an increase, followed by a decrease, is observed. The increase in current at low applied potentials (<6V) is caused by the electrodeposition of Ni(II) at the fibre surface, resulting in an increase of its conductive properties therefore more electrical current can pass the cable per time unit. After approximately 15 min, it reaches a constant value at that moment, the surface is fully covered (confirmed with X-ray photo/electron spectroscopy (XPS) analysis) with Ni. Further deposition continues but no longer affects the conductive properties of the deposited layer. 

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