Zirconium electrical resistivity

In addilion to ferrous ulluys, chromium also is added to cupper, vanadium, zirconium, and other metals to form several hundred chromium-bearing alloys. Nickel-chromium-iron alloys have high electrical resistance and are used widely as electrical heating elements. Niclirttme and ChromeI are examples. 

The most frequently used source of infrared light for infrared spectrometers is so called the Nemst stick. This stick is about two to four centimeters long and one to three millimeters thick, and is made from zirconium oxide with additions of yttrium oxide and oxides of other metals. This mixture of oxides has a negative temperature coefficient of electrical resistance. This means that its electrical conductivity increases with an increase in temperature. At room temperature, the Nemst stick is a non-conductor. Thus, an auxiliary heating is necessary for ignition of the Nernst stick. Even if the Nernst stick is red-hot, it can be heated further by electricity. The normal operating temperature of this infrared light source is approximately 1900 K. 

Figure 7.1 shows the temperature dependence of the thermal conductivity of zirconium and zircaloy-2. Figure 7.2 shows the temperature dependence of the electrical resistivity of zirconium and a zirconium-1.65 percent tin alloy, which approximates zircaloy-2 and -4. 

CEZ/RIG] Cezairliyan, A., Righini, F., Simultaneous measurements of the heat capacity, electrical resistivity and hemispherical total emittance by a pulse heating technique zirconium, 1500 to 2100 K, J. Res. Natl. Bur. Stand., Sect. A, 78, (1974), 509-514. Cited on pages 82, 90. 

CEZ/RIG] Cezairliyan, A., Righini, F., Measurement of melting point, radiance temperature (at melting point), and electrical resistivity (above 2100 K) of zirconium by a pulse heating method. Rev. Int. Hautes Temp. Refract., 12, (1975), 210-217. Cited on page 83. 

Such a high number of conditions will limit the number of candidates for such an application. Thus, tin dioxide is most often used to make sensors based on electric resistance, and zirconium to make electrochemical based sensors. 

The stable double fluoride, K TiFe, dissolved in fused sodium chloride, has been employed by Messrs. Horizons Inc., by analogy with their zirconium process. Chlorine is evolved on electrolysis, leaving an electrolyte rich in fluorides which have too high an electrical resistance for satisfactory operation over a long period. Frequent replacement of the electrolyte is therefore necessary. 

The balance of the plates were then tested ultrason-ically for bond integrity and tested for uniformity of clad thickness by resistivity measurements. Because the electrical resistivity of the l-l/2% niobium-5% zirconium alloys has nearly the same magnitude as the resistivity of the Zircaloy 2 cladding, the measurement and the variation in clad thickness could not be determined as accurately as that obtained with the 3% and 6% niobium binary alloys. 

Zirconium see also Elements electrical resistivity, 12-39 to 40 electron configuration, 1-18 to 19 heat capacity, 4-135 history, occurrence, uses, 4-1 to 42 ionization energy, 10-203 to 205 isotopes and their properties, 11-56 to 253 magnetic susceptibility, 4-142 to 147 molten, density, 4-139 to 141 physical properties, 4-133 to 134 thermal properties, 12-201 to 202 vapor pressure, 6-61 to 90 vapor pressure, high temperature, 4-136 to 137... 

M Rahman, CC Wang, W Chen, SA Akbar, C Mroz. Electrical resistivity of titanium diboride and zirconium diboride. J Am Ceram Soc 78 1380, 1995. 

The temperature dependence of the electrical resistivity of the TiB2-ZrB2 system as a function of temperature (31) obeys the same behavior as TiB2. The p298(pti cm) and m (pQ cm/K) values for ZrB2 were determined to be 7.8 and 10, both of which increase with TiB2 content. These values for TiBj were determined to be 20.4 and 36, respectively. ElecPical conduction in the diborides of intermediate compositions may be primarily via the zirconium-rich... 

Zirconium oxide is fused with alurnina in electric-arc furnaces to make alumina—zirconia abrasive grains for use in grinding wheels, coated-abrasive disks, and belts (104) (see Abrasives). The addition of zirconia improves the shock resistance of brittle alurnina and toughens the abrasive. Most of the baddeleyite imported is used for this appHcation, as is zirconia produced by burning zirconium carbide nitride. 

Uses. In spite of unique properties, there are few commercial appUcations for monolithic shapes of borides. They are used for resistance-heated boats (with boron nitride), for aluminum evaporation, and for sliding electrical contacts. There are a number of potential uses ia the control and handling of molten metals and slags where corrosion and erosion resistance are important. Titanium diboride and zirconium diboride are potential cathodes for the aluminum Hall cells (see Aluminum and aluminum alloys). Lanthanum hexaboride and cerium hexaboride are particularly useful as cathodes ia electronic devices because of their high thermal emissivities, low work functions, and resistance to poisoning. 

Zirconium, too, is produced commercially by the Kroll process, but the van Arkel-de Boer process is also useful when it is especially important to remove all oxygen and nitrogen. In this latter method the crude zirconium is heated in an evacuated vessel with a little iodine, to a temperature of about 200° C when Zrl4 volatilizes. A tungsten or zirconium filament is simultaneously electrically heated to about 1300°C. This decomposes the Zrl4 and pure zirconium is deposited on the filament. As the deposit grows the current is steadily increased so as to maintain the temperatures. The method is applicable to many metals by judicious adjustment of the temperatures. Zirconium has a high corrosion resistance and in certain chemical plants is preferred to alternatives such as stainless... 

Some polysiloxanes are curable with lead monoxide, with a consequent reduction in both curing time and temperature. High-frequency electrical energy vulcanizes in one case at least. Zirconium naphthenate imparts improved resistance to high temperatures. Barium salts are said to prevent blooming. Sulfur dichloride is also used. Some resins are solidified by pressure vulcanization, using di-f-butyl peroxide. Improvements are to be found in lower condensation temperatures and shorter times of treatment... 

Production of ZrCl4. Zirconium oxide from the hafnium-separation step was mixed with carbon black, dextrin, and water in proportions 142 Zr02, 142 C, 8 dextrin, and 8 water. The mixture was pressed into small briquettes (3.8 X 2.5 X 1.9 cm) and dried at 120°C in a tray drier. The oxide briquettes were charged to the reaction zone of a vertical-shaft chlorinator lined with silica brick. The charge was first heated by carbon resistance strips until it became conductive. During production, the bed temperature was maintained at 600 to 800 C by an electric current passed directly through the bed. After steady conditions were reached, a reactor 66 cm in diameter produced about 25 kg ZrCLt/h. The ZrCU was condensed from the reaction products in two cyclone-shaped aftercondensers in series, and the chlorine off-gas was removed in a water scrubbing tower. 

EINECS 234-963-5 Zirconium boride Zirconium boride (ZrB2) Zirconium diboride Zirconium diboride (ZrB2). Refractory for aircraft and rocket applications, thermocouple protection tubes, high-temp, electrical conductor, cutting-tool component, coating tantalum, cathode in high-temp, electrochemical systems oxidation-resistant composites. Atomergic Chemetals Cerac Noah Cham. 

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