Tungsten oxide is considered one of the most refractory in this class of inorganic substances. In order to characterize the metal, let's analyze the qualities of the metal itself.
Features of tungsten
To understand the practical importance of tungsten oxide, we note that the metal itself has electrical resistance, a coefficient of linear expansion, and a high melting point.
Pure tungsten has high ductility. The metal will dissolve in acid only when heated to a temperature of 5000 oC. It reacts with carbon, forming tungsten carbide as a reaction product. The resulting joint is highly durable.
The most common tungsten oxide is tungsten anhydride. The main advantage of the chemical compound is the ability to reduce powder to metal, forming lower oxides as by-products.
The metal is characterized by high density, brittleness and the ability to form tungsten oxide at low temperatures.
Tungsten alloys
Scientists identify single-phase types of alloys, which includethere are one or more elements. The most well-known compound of tungsten with molybdenum. Alloying the alloy with molybdenum increases the tensile strength of tungsten.
Single-phase alloys are compounds: tungsten - zirconium, tungsten - hafnium, tungsten - niobium. Rhenium gives maximum plasticity to tungsten. Its addition does not affect the performance of refractory metal.
Getting metal
It is impossible to obtain alloys of refractory tungsten in the traditional way: reaching the melting point, the metal instantly passes into a gaseous form. The main option for obtaining pure metal is electrolysis. In industrial volumes, powder metallurgy is used to obtain tungsten alloys. To do this, create special technological conditions using vacuum.
Being in nature
Tungsten oxide, whose formula is WO3, is called the highest compound. It does not occur in nature in its pure form, but is part of tungsten ores. The process of extraction and processing of refractory metal involves several stages.
Higher tungsten oxide is isolated from the ore mass. Next, the compound is enriched, and after processing, pure metal is isolated.
In the process of making thin tungsten wire, care must be taken to completely remove impurities. Otherwise, the specifications of the finished product will be significantly reduced.
Spheres of use of tungsten
How to restore tungsten oxide? Hydrogen interacting with this compound helps to obtain a pure metal. It is essential in the manufacture of filaments, X-ray tubes, heaters and vacuum furnace screens, which are designed for use at high temperatures.
Steel, in which tungsten is an alloying element, has high strength properties. Products made from such an alloy are used in the manufacture of medical instruments, cutting plates for drilling wells. The main advantage of the connection is resistance to mechanical deformation.
The probability of cracks and chips occurring during the operation of finished products is rather low. The most popular steel grade, which includes tungsten, is considered to win.
The scrap of this rare metal is used to make high-quality catalysts, all kinds of paints, special pigments, etc. Tungsten crucibles and containers for radioactive waste are widely used in the modern nuclear industry.
Refractoriness of metal plays a special role in arc welding. Since tungsten in its pure form is considered a rather rare metal, to obtain it, the procedure for enrichment and processing of tungsten ore is carried out. In its pure form, it has a light gray color with a characteristic metallic sheen. Standard tungsten alloys, referred to as stellites, also include cob alt and chromium. The main component in such compounds is cob alt. Alloysin demand in mechanical engineering.
Tungsten oxides
What are the features of tungsten oxide (6), the formula of which is WO3? The metal is able to exhibit different degrees of oxidation: the maximum stability has options with metal valence (4) and (6). The first compound of the type WO2 belongs to acidic oxides and has the following characteristics: high melting point and special density. This chemical compound is almost insoluble in water, but when heated, it can dissolve in acids and alkalis. In the chemical industry, it is used as a catalyst in some reactions. For example, the compound WO2 is used in the production of ceramic products.
Tungsten oxide, having a valency (6), also exhibits characteristic acidic properties. This compound reacts with alkalis, but is not able to dissolve in water. Given that the compound has a high melting point, it is used only as an accelerator of chemical processes.
Conclusion
In the course of inorganic chemistry, special attention is paid to the study of oxides, the analysis of their properties and the peculiarities of their application in industry. For example, at the final exam, ninth-graders are offered the task of the following content: "Make formulas for oxides of copper, iron, tungsten, and also determine their basic chemical properties."
In order to successfully cope with the task, it is necessary to have an idea about the features of oxides. As suchconsider binary compounds in which the second element is oxygen. All oxides are usually classified into three groups: basic, acidic, amphoteric.
Iron and copper are elements of a secondary subgroup, therefore they are able to exhibit variable valences. For copper, only two variants of oxides can be written that exhibit basic properties - Cu2O and CuO.
Iron is not located in the main subgroup of chemical elements, therefore, oxidation states +2 and +3 take place. In these cases, oxides of the following types are formed - FeO and Fe2O3.
Tungsten in binary compounds with oxygen in most often exhibits valencies (4) and (6). Both oxides of this metal exhibit acidic properties, so they are used in industry as chemical process accelerators.
The main purpose of all tungsten oxides is to isolate pure metal from them, which is in demand in the chemical and metallurgical industries.
