Rhenium is silvery white heavy metal. It’s melting point is 3180℃and boiling point is 5600℃ It’s density is 21.02g/cm3 and its symbol is “Re” .The atomic coefficient of Rhenium is 75 and atomic weight is 186.207.Rhenium is in the periodic system ⅦB. In 1872,according to the Periodic law of elements, the Russian Dmitri Mendeleev predicted that there was a chemical element with an atomic weight 190 and similar to the nature of manganese, named Manganese-like. It was discovered byWalter Noddack, Ida Tacke, and Otto Berg in Germany in 1925 when they detected the element in platinum ore and in the mineral columbite, they named it Rhenium. Rhenium is from Latin Rhenus meaning: 'Rhine'. The estimated average concentration of Rhenium in the earth’s crust is 1 part per billion (ppb). There’re two naturally occurring isotopes for Rhenium. Rhenium-185 is one stable isotope while rhenium-187 is the radioactive isotope.
Rhenium is stable at room temperature and starting to be oxidized when temperature reaches 300℃. Rhenium and sulfur vapor will synthesize into rhenium disulfide and halide with fluorine, chlorine, bromine. The chemical properties of it depend on its aggregation and rhenium powder is more lively. The oxidation state of rhenium including -1,+1,+2,+3,+4,+5,+6 and +7 valence. The oxides of rhenium are Re2O、Re2O3、ReO2、ReO3、Re2O7.
The reserve of Rhenium is rarely in the earth’s crust, it usually associates with molybdenum and copper, also in uranium ores. By 1930,the world’s total output of Rhenium was only 3 gram. Even till now, the annual output of Rhenium is only about dozens of tons which is much less than the other metals.
Rhenium is a kind of very hard silvery-white metal, it looks like platinum. Rhenium is high melting point metal, only exceeded by tungsten. The chemical property of rhenium is stable and it has strong corrosion resistance. It is not oxidized in the air, acid but alkali has a little corrosion effect on it. Rhenium has extremely high mechanical strength, rhenium alloy wire that is thinner than human hair can withstand more than 7 kilogram of gravity. Besides, rhenium also has high resistance and other electrical characteristics.
With the various of excellent properties mentioned above, rhenium has become a kind of important material used in many fields. In metallurgical industry, rhenium is used as additive for alloys and could improve the performance of the alloy. For instance, pure tungsten and molybdenum will become brittle as glass under low temperature which is difficult to process, therefore their usages are restricted. However, the tungsten rhenium alloy or molybdenum rhenium alloy adding proper amount of rhenium, have good plasticity and can be processed into different kinds of structural materials meanwhile remain high hardness, high strength and high temperature resistance . Many parts of American manned spacecraft are made of this type of alloys. Chromium nickel adding a small amount of rhenium adding can greatly improve its melting point and strength. Components made of this alloy, its service time could be extended several times to dozens of times.
Rhenium is commonly used in the field of electrical, electronic and instrument. Electric contactor—one important component used in automatic electronic relay and many other electronic devices is usually made of tungsten. In some adverse working conditions, the life time of this electronic contactor is very short, but electronic contactor made of rhenium can be used for months or even years continuously due to its unique properties. Rhenium alloy is good material for manufacturing cathode head which is adopted by some high power transmitting tubes, magnetoelectric meter and other electric vacuum instrument. Rhenium is extremely wear resistant, the axis and pointer of the compass and precision instrument made of rhenium alloy is both accurate and durable. Coated with a layer of rhenium on the surface of ordinary tungsten filament, the service life can be extended 5 to 10 times. Rhenium can also be used to make pen point and rhenium pen has a long lifetime.
Today,common rhenium products that we usually know also include WRe thermocouple wire used for temperature measurement. Rhenium is also used in many parts of aerospace equipment and aircraft engine turbine blades.
In brief, rhenium can be used widely.Its usages were just limited due to its high value.
RHENIUM (III) CHLORIDE