The physical and chemical properties of tungsten oxide and its preparation method

Tungsten trioxide is a powder metallurgical raw material for the production of cemented carbide and tungsten products. According to the national standard (GB/T 3457-1998), it is divided into two types: tungsten trioxide (yellow tungsten for short), with the molecular formula WO3, and blue tungsten oxide (blue tungsten for short, which is a mixed tungsten oxide). W20O58. Yellow tungsten is light yellow crystalline powder, and blue tungsten is dark blue or blue-black crystalline powder.

The physical and chemical properties of tungsten oxide

Tungsten trioxide is a light yellow triclinic powder crystal. When the temperature is higher than 740°C, it turns into orange tetragonal crystals, and returns to the original state after cooling. It is stable in the air, the melting point is 1473°C, the boiling point is higher than 1750°C, and the relative density is 7.16.

Tungsten trioxide is the most stable kind of tungsten oxide. It is insoluble in water and inorganic acids except hydrofluoric acid. It can be dissolved in hot concentrated sodium hydroxide solution and ammonia to form soluble tungstate. When the temperature is higher than 650℃, it can be reduced by H2, and it can be reduced by C to obtain tungsten powder at 1000～1100℃.

Preparation method of tungsten oxide

1. Ammonium tungstate method tungsten concentrate is alkaline hydrolyzed by sodium hydroxide, neutralized with hydrochloric acid, and then reacted with ammonium chloride to generate ammonium tungstate, and then hydrochloric acid is added for acidolysis reaction to generate tungstic acid, which is then decomposed by roasting , Crush to obtain tungsten trioxide.

2. Hydrochloric acid decomposition method of tungstate. The saturated aqueous solution of tungstate such as sodium tungstate Na2WO4 and calcium tungstate CaWO4 is heated, and the solution is slowly added dropwise to 2 to 3 times the excess boiling concentrated hydrochloric acid by mole. According to the above reaction, yellow tungstic acid is precipitated. At this time, if the dropping speed is too fast or the liquid temperature drops, suspended or colloidal precipitates are easily formed, which will bring difficulties to the next step. After dripping, heat continuously on the water bath for 1 hour, and the precipitate becomes easy to filter. After standing, it was washed several times with 5% ammonium nitrate aqueous solution to completely remove Cl-. After filtration, it is dried at 120°C, and finally heated to 600°C tungstic acid is completely dehydrated into tungsten trioxide.

3. Thermal decomposition method of ammonium paratungstate. Put ammonium paratungstate (NH4)10W12O41·11H2O purified by recrystallization into a porcelain crucible, and when heated to above 400℃, ammonia volatilizes to obtain tungsten trioxide. 

Overview of tungsten oxide WO3 powder

Tungsten oxide WO3 is also called tungsten trioxide. Tungsten trioxide is an inorganic substance, chemical formula WO3, is a kind of light yellow crystalline powder. Insoluble in water, soluble in alkali, slightly soluble in acid. Used in the manufacture of high melting point alloys and cemented carbides, tungsten wires and fireproof materials. Tungsten ore and soda ash are co-crystallized and then prepared by adding acid. Tungsten trioxide is a light yellow rhombus crystalline powder. The color changes from light to dark when heated. The specific gravity is 7.16g/cm3, the melting point is 1473°C, the boiling point is 1750°C, and it sublimates significantly at 850°C and turns green when melted. It is stable in air, insoluble in water and inorganic acid except hydrofluoric acid, and slowly dissolves in ammonia and concentrated hot sodium hydroxide solution. The structure of tungsten trioxide depends on the temperature: above 740°C is tetragonal crystal system, 330-740°C orthorhombic crystal system, 17-330°C monoclinic crystal system, -50-17°C triclinic crystal system . The monoclinic structure is the most common, and its space group is P21/n.

Tungsten has a long history, dating back to the discovery of the 18th century. Peter was the first to recognize the new element of the natural mineral tungsten, originally called tungsten, interpreting its element symbol as the chosen "W". The Swedish chemist Karl Scheelite is also responsible for discovering the mineral scheelite through his research.

In 1841, chemist Robert completed the first process of preparing tungsten trioxide and sodium tungstate. Soon after, his work was patented and he is considered the founder of the tungsten chemical system.

Tungsten trioxide WO3 powder is one of the most stable tungsten oxides. It is insoluble in water. Inorganic acids other than hydrofluoric acid can be dissolved in hot concentrated sodium hydroxide solution and ammonia to form soluble tungstate. When the temperature is higher than 650℃, it can be reduced with H2, and when the temperature is 1000～1100℃, it can be reduced with C to obtain tungsten powder.

The application of tungsten oxide WO3 powder

Tungsten trioxide has many uses in daily life. It is commonly used in the manufacture of industrial X-ray screen phosphors and tungstate for fireproof fabrics. Because it is rich in yellow elements, tungsten oxide is also used as a pigment in ceramics and paints. In addition, other application examples of tungsten trioxide are as follows:

Tungsten trioxide WO3 powder is mainly used for calcining reduction to produce tungsten powder and tungsten carbide powder, and further used for the production of cemented carbide products, such as the manufacture of tools and molds.

Tungsten trioxide WO3 powder can also be used to make pure tungsten products, tungsten rods, tungsten wires, tungsten electrodes;

And use counterweight and radiation shielding materials.

In industrial production, a small amount is also used as a colorant for yellow ceramics. In the shipbuilding industry, tungsten oxide is used as an important anti-corrosion paint and coating material.

Tungsten trioxide WO3 powder has been used to produce electrochromic windows and smart windows. These windows are electrically switched glass, and the light transmittance and applied voltage change. This allows users to tint their windows through changes in heat or light.

Part of tungsten oxide is used in the production of chemical products, such as paints and coatings, and catalysts for the petroleum industry. But tungsten oxide is an intermediate product. A large amount of tungsten oxide WO3 powder is used in metal tungsten powder and tungsten carbide powder, and then used in the production of metal tungsten products, and a large number of applications and production of tungsten alloy products, into tungsten copper, tungsten nickel, tungsten nickel Iron, tungsten silver, tungsten rhenium, tungsten thorium, etc. The most widely used in contemporary industrial fields are tungsten-based cemented carbide products of various grades and uses.

Tungsten trioxide WO3 powder is also used in ceramic colorants and analytical reagents; used in the production of metallic tungsten materials; gas sensors; fireproof cloth; imaging; large-area display; catalysts; ceramic pigments; humidity sensors; infrared switch cabinets; high-density storage equipment Catalyst; Temperature sensor; Used for X-ray screens and fireproof textiles; Tungstate; Wastewater treatment; Solar energy conversion; Production of tungsten carbide, cemented carbide, cutting cooling, superhard molds, tungsten belts, etc. through powder metallurgy.

Tungsten oxide WO3 powder price

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Tungsten Oxide WO3 Powder Supplier

As a global supplier of tungsten oxide and tungsten trioxide powder, Tanki New Materials Co., Ltd. has extensive experience in the performance, application and cost-effective manufacturing of advanced engineering materials. The company has successfully developed a series of powder materials (including oxides, carbides, nitrides, single metals, etc.), high-purity targets, functional ceramics, structural devices, and can provide OEM services.