Tungsten Oxide

The properties of tungsten powder s may be seriously affected by the third element. In production, these characteristics can be used to add third elements to control the particle size of tungsten powder to produce some special kinds of tungsten oxide. This method is called doping. When doped, the tungsten oxide is added to the aqueous solution of the element compound. The most suitable for doping is not yellow tungsten nor purple tungsten, but blue tungsten. The commonly doped elements are sodium, lithium, chromium, and rare earth elements. 1. Sodium-doped: The addition of sodium compounds is a common method in preparing coarse tungsten powders, the amount of sodium is usually between 50-200 and m/g. At 1000°C under wet hydrogen conditions, tungsten powders with an average particle size of 10-25 um can be obtained according to the thickness of the material layer, high temperature ensures strong volatilization of sodium at the end of the reduction process, it is ...

Violet tungsten oxide is a kind of tungsten oxide product developed in China in recent years. Its phase composition is WO 2.72  or W 18 O 49 . If you have any inquiry of  tungsten , please feel free to contact us: Email:  sales@chinatungsten.com / sales@xiamentungsten.com Tel.: +86 592 5129696/+86 592 5129595 Fax: +86 592 5129797 Scan QR code of Chinatungsten Wechat platform to follow up the daily latest price and market of tungsten, molybdenum and rare earth.

The hydrogen reduction process of tungsten oxide is a complex system engineering, in the process, the concentration of tungsten powder is also an important physical parameter. It determines the plasticity of the tungsten products, and the good agglomeration is the characteristic of tungsten powder for the production of plastic tungsten products. Hydrogen reduction tungsten powder particle aggregation types can be divided into three kinds: 1. Under low temperature and dry hydrogen conditions, the sponge metal is reduced and the particle aggregate has the shape of tungsten oxide precursor, very small crystals are bonded together in relatively compact or looser ways, usually the aggregation is called pseudo crystalline, and the smaller the size of the crystal, the higher the concentration of the particles. 2. Particles grown by chemical vapor migration are welded together with larger tungsten crystals. This type of particle occurs mainly during the reduction proce...

In the process of hydrogen reduction of tungsten oxide , the vapor pressure of tungsten oxide increases obviously when there is water vapor at high temperature. This increase in vapor pressure is due to the reaction of various tungsten oxides with water vapor to form a volatile hydrated tungsten oxide. In the W - O - H system, the hydrated tungsten oxide is much more volatile than other volatile tungsten compounds. Most scholars at home and abroad believe that it is the volatile hydrated tungsten oxide that causes the chemical vapor transfer (CVT) process of tungsten. Moreover, the CVT process runs through the whole stage of the reduction of tungsten oxide and hydrogen. It has a decisive influence on the physical and chemical properties of tungsten powder. In the CVT process, tungsten and its oxides are contacted with water vapor to produce hydrated tungsten oxide , which is volatilized to the gas phase and undergoes a homogeneous reduction reaction with H 2 . The re...

In the process of hydrogen reduction of tungsten oxide , the effect of the reduction is not only the metal elements, there are some trace elements, such as rare earth elements. The effects of trace elements are related not only to quantity, but also to the shape and location of individual elements and the entry stage, for example, the elements that form fine grain particles at grain boundaries are different from the same elements in solid solutions. They are soluble in the bonding phase and different from the tungsten carbide grains. Some scholars believe that the addition of lanthanum or yttrium (La) (Y) in hydrogen reduction of tungsten oxide, can play a similar role to that of Al. In the process of research, scholars used the doping method of wet mixing and flow drying to prepare the blue tungsten powder, and push the boat by reverse hydrogen, the decomposition process is performed in two stages, namely at 500 °C, 850 °C, 900 °C, 950 °C, 1000 °C temperature point fi...

In the production of tungsten metal by powder metallurgy, the chemical purity is especially important because the subsequent sintering process can only be achieved by evaporation to a certain extent. With the development of industry, the requirement of the purity of tungsten powder is increasing day by day, because the impurities left after the sintering of tungsten powder have a great influence on the processability and properties of the final products. In the production process of tungsten concentrate to tungsten powder, tungsten purity is constantly improved, and the purity is high when APT is made. However, when APT is processed into tungsten powder, the purity decreases. Why? According to the study, tungsten powder impurities mainly from the material and the reduction of the furnace tube and metal boat contact, as a result, the impurity content is increased, and these impurities are present in a heterogeneous form, the result is the increase in impurity conte...

Nano tungsten trioxide is a high quality n-type semiconductor material, with excellent gas sensitivity to H 2 S, NH 3 , H 2 O 3  and other gases are sensitive. In modern industry is often used to produce gas sensors and electrochromic device. A gas sensor is a device that converts the type of gas and its associated information into electrical signals so that it can detect, monitor, and alarm. Tungsten trioxide (WO 3 ) is a n-type semiconductor with wide band gap, its excellent sensitivity and selectivity makes it becomes the main material of the sensor elements. In the field of coal, petroleum, chemical, power and other production, using tungsten trioxide as a component of the sensor can be timely and accurate to flammable, explosive, toxic, harmful gas detection and automatic control. Tungsten trioxide sensor was first used to detect H 2 S and H 2 , Japanese scholars in 1992 for the first time reported WO 3  sintered coating on the very low concentrati...