Tungsten Oxide

Among the vanadium oxides, vanadium dioxide is distinguished by its rapid and abrupt phase transition, and its phase transition temperature is 68  °C. The reversible change from low temperature monoclinic system to high temperature tetragonal system leads to great changes in physical properties such as resistivity, optical transmittance, permeability and so on. This feature makes it very promising in intelligent switches, electronic devices and optoelectronic devices. However, in daily life, the application temperature of 68 degrees is still too high, so it is necessary to reduce the VO 2  phase transition temperature, so that VO 2  can be widely used. In recent years, many studies have shown that doping of other elements in VO 2  can effectively reduce its phase transition point. Especially the high valence metal ions, such as MO 6+ , W 6+  and so on, doping effect is particularly significant. The amount of ammonium metatungstate was mixed with vanadium oxide b...

Tungsten has a high melting point, high density, high hardness, saturated vapor pressure, low coefficient of thermal expansion and other characteristics. Copper has high thermal conductivity properties, tungsten copper alloy combination is made known to all the materials in aerospace and military fields. The traditional preparation of tungsten copper alloy mainly adopts the method of mechanical mixing, forming and sintering of tungsten powder and copper powder, or using infiltration process. The method is relatively simple, but there are some defects, because of the great difference between tungsten and copper, tungsten and copper can only form pseudo alloy shape, and it is difficult to achieve uniform distribution of tungsten and copper in the interior, resulting in lower or unstable properties.  With the development of Aeronautics and Astronautics and military industry, the demand for tungsten copper exothermic sweating material is higher and higher, Chinese scholars created a po...

The preparation of tungsten powder from APT is usually calcined in the weak reducing atmosphere to produce yellow tungsten, blue tungsten or purple tungsten. Then, the reduction of hydrogen to produce tungsten powder is a commonly used method in industry. The tungsten powder prepared by this process is a kind of very regular polycrystal, which is the main raw material for preparing tungsten alloy and tungsten carbide. But some scholars believe that the traditional process is long, easy to bring in impurities, production costs are relatively high, so he proposed a step through tungsten oxide process, the direct preparation of tungsten powder from ammonium paratungstate one step reduction method. The main process of one-step reduction method is as follows: 1. In the first step to control the formation of the intermediate of blue tungsten, a certain proportion of hydrogen and nitrogen mixed gas is replaced into ammonia in the reduction furnace. 2. Loading the amount of 50g, hydrogen flow ...

China is a dominant country of tungsten resources and tungsten powder export, and export control conditions of 4xy3, has canceled export quota in 2016 and transferred to goods of export license administration. 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 specific surface area is the total area of the unit mass material, the unit is m 2  / g. Generally refers to a specific surface area of a solid material, such as powders, fibers, particles, and other bulk materials. It is difficult to measure the surface area of powder or porous material. They not only have irregular outer surface, but also complex inner surface. They have large specific surface area and large activity, so they have strong adsorption ability. Tungsten powder specific surface area is usually 0.01m 2 /g (coarse tungsten powder) to 12m 2 /g (fine tungsten powder), sintering active surface area is a measure of tungsten powder (solid state sintering), dissolution characteristics (liquid phase sintering) and reaction ability in the carbonization process and gas solid material between the main index. According to the specific surface area value, the average particle size of tungsten powder can be calculated, and the reduction effect of tungsten pow...

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 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...

Tungsten powder is the main raw material for processing powder metallurgy tungsten and tungsten alloy.  In the extraction and smelting of tungsten, the production of metal tungsten powder is a key step in the production of tungsten and tungsten alloy because the properties of tungsten powder largely affect the subsequent operation of tungsten products. Pure tungsten powder can be made into wires, bars, tubes, plates and other processed materials and products of a certain shape. Tungsten powder and other metal powder, can be made into all kinds of tungsten alloy, such as tungsten molybdenum alloys, tungsten rhenium alloy, tungsten copper alloy and high density tungsten alloy. Another important application of tungsten powder is to make tungsten carbide powder, and then prepare carbide tools, such as turning tools, milling cutters, drills and dies, etc. Hydrogen tungsten reduction and carbon reduction are the main methods for the production of tungsten powd...

Fine and uniformity tungsten powder are key point for producing carbide, and micron and submicron tungsten carbide powder is useful to producing carbide. According to the relevant academic report found that single tungsten oxide can produce submicron or micron tungsten powder. Using violet tungsten oxide (VTO) producing fine tungsten oxide not only the process of it is simple as well as process parameters are easy to control and also equipment are not complex etc. Producing process as follows: 1. VTO were first reduction in hydrogen, along a first temperature of 640 ℃, the second temperature of 760 ℃, third temperature of 860 ℃, when the temperature reaches 860 ℃ heat preservation for 20min. 2. in the air at 500 ℃ making tungsten powder to oxidation with slowly heated for the first time, then heat preservation for 10min. 3. Replace the first step and second to continuous cycle reduction reaction. 4. Using alcohol on the analytical results above steps were dispersed pattern, t...

Fine tungsten powder is an important raw material for producing tungsten carbide powder, to improve the performance of carbide tungsten is necessary to reduce or eliminate the coarse tungsten powder particles. Otherwise it will cause tungsten carbide cracks, fracture and other phenomena in the course. After studies the process of using blue tungsten oxide as raw material to produce fine tungsten powder research found that by using exceptionally pure ammonium paratungstate calcinate in ammonia to get blue tungsten and then go through the cyclic oxidation producing fine tungsten powder, and the tungsten powder properties is better which is less coarse. Producing process as follows: 1. Slow heating exceptionally pure ammonium paratungstate which is in ammonia to 600 ℃, when the temperature reach 600℃for 10min heat preservation to produce  blue tungsten oxide. 2. To obtain tungsten powder by restoring blue tungsten oxide in hydrogen. 3. The obtained tungsten powder slowly heating ...

Fine and uniformity tungsten powder are key point for producing carbide, and micron and submicron tungsten carbide powder is useful to producing carbide. According to the relevant academic report found that single tungsten oxide can produce submicron or micron tungsten powder. Using violet tungsten oxide (VTO) producing fine tungsten oxide not only the process of it is simple as well as process parameters are easy to control and also equipment are not complex etc. Producing process as follows: 1. VTO were first reduction in hydrogen, along a first temperature of 640 ℃, the second temperature of 760 ℃, third temperature of 860 ℃, when the temperature reaches 860 ℃ heat preservation for 20min. 2. in the air at 500 ℃ making tungsten powder to oxidation with slowly heated for the first time, then heat preservation for 10min. 3. Replace the first step and second to continuous cycle reduction reaction. 4. Using alcohol on the analytical results above steps were dispersed pattern, then ...