Circle, rod rhenium
Rhenium wire and the circle is inseparable from the development of the world economy and using high technologies. These materials are today indispensable in aviation, space technology, nuclear energy, electronics, military industry, engineering and electronics.
| Physical properties Re | |
|---|---|
| Atomic (molar) mass, g/mol | 186,2 |
| Oxidation | 7, 6, 5, 4, 3, 2, -1 |
| Density [g/cm3] | 21,02 |
| The melting temperature t°C | 3186°C |
| The heat of fusion kJ/mol | 34 |
| The thermal conductivity K [W/(m·K)] | 48 |
| Heat of evaporation kJ/mol | 704 |
Production
Procurement of rhenium are manufactured by means of powder metallurgy. First get the rod billet, after which it is heated, forged in the forging of a special rotary machine and get bars with a diameter of 2−3 mm. in the following, due to the high rhenium plasticity, rods pull into the thinnest of thin wire, with a diameter of a few microns.
Application
Rhenium — structural non-alternative material for the manufacture of parts and components of special equipment, which is designed to operate at temperatures above 1000 °C in corrosive environments. In electrical and electronics from rhenium alloys produced the grid, the filament heaters of the cathodes for cathode ray tubes, in thermionic generators, the generator and the receiving-amplifying tubes, the filaments in ion gauges and mass spectrometers and other similar devices.
In apparatus for surveying a stable operation of mechanical or optical nodes, which are fixed on thin metal hangers. Suspensions of this type are in theodolites, levels, gyrotheodolite. The most accurate suspensions are those which wires and ribbons from rhenium alloys.
In measuring instruments for the high temperatures (about 2500°C) used thermocouple alloys of tungsten and rhenium. They are much more conventional thermocouples of molybdenum and tungsten. Termoelektrodny the wire is made of tungsten alloy with rhenium — BP-20 (rhenium — 20%), BAP-5 (with silica-and aluminum additives and rhenium -5%) and BP-5 (rhenium — 5%), which is obtained by powder metallurgy.
Thermocouple wire brands ВР5 and ВР20 has different nominal values of thermoelectric power, which are reflected in the calibration. Tungsten-rhenium thermocouples are manufactured in molybdenum and ceramic covers. Thermoelectrodes brand BAP-5 (BP-5) is completed only with the electrode and the thermoelectrodes brand BP-20, which have the same statistical characteristics taken from one and the series.
Inside incandescent bulbs with time in the glass appears dark plaque, which is the end result of the water cycle. With the most careful removal of the lamps of the air and some water vapor always remains. The water dissociates at high temperature into oxygen and hydrogen; oxidizing the tungsten hot filament. After that, the oxide of tungsten is vaporized, deposited on glass, metal tungsten, which is restored by hydrogen. Thus, the smallest particles of tungsten from the filament evaporates, and the glass form a dark spot, and the filament becomes thinner until break. At a temperature of 1300 °C, the rhenium is resistant to water half cycle of the tungsten and at a temperature of 1750 °C eight times. The alloys of rhenium with tungsten — perfect for the production of filaments, in contrast to pure rhenium.
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