Tungsten Oxide

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 powder

Tungstate is a typical self-activated luminescent material. Its luminescence spectrum is very stable, and its intrinsic luminescence spectrum is very wide and occupies most of the visible region. The cation in the tungstate strongly affects the position of the emission band. With the increase of atomic number of the cation, the peak shift of the emission band is blue, and the bandwidth is from 250 to 300 nm. It was not long before Roentgen discovered X-rays in 18 century, people use the penetrating power of the rays to check the internal condition of the human body or objects, and to observe or photograph the image directly by the enhancement of the ray emitting material. In 1896 found that CaWO 4  can be used as phosphor, in 1906, Puppin first used CaWO 4  as X-ray luminescent material. In 1916, Patterson made it a luminescent material for X-ray intensifying screen. In recent years, a great deal of research work has been done on the luminescence properties of single tu

With the rapid development of industry, while bringing great economic benefits, the environmental pollution caused by the waste water is also becoming more and more serious. Organic industrial wastewater with high concentration and low biodegradability, deep color, complex composition, containing oil, acids, amines, demulsifier and other pollutants, organic wastewater is difficult to degrade, bring unpredictable effects and harm to the ecological system. The photocatalytic purification of organic compounds in water is a new technology, which uses the sun to degrade organic matter, energy saving and no pollution to environment, has great application prospect. Nano tungsten trioxide is a high quality n-type semiconductor material, as photocatalyst, n-type semiconductor has many kinds, such as TiO 2 , ZnO, Fe 2 O 3 , CdS and WO 3 . The results show that WO 3  has good photocatalytic stability and is an ideal catalyst for photocatalytic degradation of pollutants in water

With the growing awareness of environmental protection and recycling of resources, more and more researches are being made on the degradation of organic pollutants. The photocatalytic degradation of organic compounds is a new technology, which uses sunlight to degrade organic compounds, saves energy and does not pollute the environment. Therefore, it has great application prospects. Nano tungsten trioxide is a high quality n-type semiconductor material, as a photocatalyst, WO 3  photocatalytic stability is good, photocatalytic degradation of air pollutants also has an ideal catalytic effect, and China is rich in tungsten reserves, ranking first in the world, WO 3  has a wide range of sources. In the role of purification of air, the main goal of nano tungsten trioxide is to improve the energy utilization efficiency of hydrogen and oxygen. Some scholars have summarized the nano tungsten oxide as a catalyst for several key factors: (1) Nanostructured materials prov

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 only

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 reduce

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 content.

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 concentration of NOX has a good sel

With the development of alloy industry, there is also a polarizing demand for tungsten powder. Not only has ultrafine tungsten powder, but also has ultra coarse tungsten powder. In industrial production, ultrafine tungsten powder is widely used, and the preparation of ultrafine tungsten powder is complicated. Therefore, it has been studied more. However, ultra coarse tungsten powder also has a specific use.  Ultra coarse tungsten powder is a coarser tungsten powder with a particle size greater than 20 microns. It has the advantages of good strength and toughness. It is widely used in the field of oil drilling, mining tools, stamping die, hard material etc. How to prepare ultra coarse tungsten? Just reverse the thinking of preparing ultrafine tungsten powder. The traditional scheme of preparing ultra coarse tungsten powder is based on the preparation of ultrafine tungsten powder as negative teaching material. 1. Try to improve fisher particle size of tungsten raw

Ultrafine tungsten powder is superior to common coarse grain material in mechanical, therefore, the mechanical properties, physical properties and chemical properties are better than those of ordinary coarse-grained materials.  However, the preparation of ultrafine tungsten powder is more stringent than ordinary tungsten powder, not only have better quality raw materials, but also more suitable methods and equipment are required. Since 1950s, a great deal of research work has been done on tungsten smelting industry both at home and abroad, and many years of systematic research have been carried out on the preparation of ultrafine tungsten powder, and some effective methods have been developed. Hydrogen reduction is the main method of preparing ultrafine tungsten powder. It is simple, advanced, reasonable, stable and reliable, low cost and so on. With the development of tungsten powder manufacturing, great progress has been made in the selection of tungsten oxide raw mater

Hydrogen reduction is the main method for preparing ultrafine tungsten powder. It is a rather complicated physical and chemical process, including chemical transformation, phase change process, solid phase diffusion and chemical vapor transfer. In W-O-H there are 6 solidification phase, which are: tungsten trioxide (WO 3 ), beta tungsten oxide (WO 2.9 , W 20 O 58 , blue tungsten) gamma tungsten oxide (WO 2.72 , W 18 O 49 , Purple Tungsten) two tungsten oxide (WO 2 ), -W alpha and beta -W. Therefore, the process of hydrogen reduction reaction of tungsten oxide is complex, and different reduction processes will occur with the change of temperature and humidity: In a high temperature and a humid reducing atmosphere, the reduction proceeds in distinct stages ( WO 3  → WO 2.9  → WO 2.72  → WO 2 → W ); In low temperature and dry hydrogen, it is possible to reduce tungsten oxide to tungsten powder directly from high valence tungsten oxide ( WO 2.9  → W，WO 2.72  → W ), the process is

The hydrogen reduction process of tungsten oxide, is a very complex physical and chemical processes, including chemical conversion, phase transformation, solid diffusion and so on. The process generally is: tungsten oxide, hydrogen reduction, sifting, blending, tungsten powder. Different tungsten oxide reduction process of reaction pathways, the reaction speed is different, in general, the reduction reaction pathway and to avoid the simple single reaction generated in the process of WO 2  is beneficial to preparing fine tungsten powder uniformly. That is to say, the tungsten powder obtained by route WO 2.9  → W or WO 2.72  → W would be more satisfactory. Hydrogen reduction of tungsten oxide is usually carried out in a multiple tube furnace or a rotary furnace. Multiple tube reduction furnace has 3 to 5 containers used for loading, use artificial way in accordance with the order of loading and unloading material, excessive hydrogen or against the tungsten material movemen