2018年12月3日星期一

Tungsten Powder Specific Surface Area

The specific surface area is the total area of the unit mass material, the unit is m2 / g. Generally refers to a specific surface area of a solid material, such as powders, fibers, particles, and other bulk materials.

tungsten powder image

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 0.01m2/g (coarse tungsten powder) to 12m2/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 has been judged. It is worth mentioning that, the finer the size of tungsten powder, the powder surface is often not "smooth", but "rough", and even a certain degree of micropores, this is different from what we expected, so the specific surface area of ultrafine tungsten powder will be 2-4 times larger.

tungsten powder image

The large specific surface area of ultrafine tungsten powder means that the high specific surface energy is stored in the developed surface, therefore, ultrafine tungsten powder is easy to oxidize when exposed to air and is prone to spontaneous combustion when subjected to friction or mechanical vibration.

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Why Does X-Ray Machines Require Tungstate Materials?

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.

X-ray machine image

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 CaWO4 can be used as phosphor, in 1906, Puppin first used CaWO4 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 tungstate doped with rare earth ions, especially for doping rare earth ions.

Some scholars have found that tungstate luminous brightness increases with the purity of the compound. Tungstate can be activated by some impurities, which are doped into the tungstate lattice and then give it a special property of luminescence. There are not many kinds of impurities, almost limited to rare earth elements.

In 1948, some scholars studied the tungstate materials doped with rare earth powder. It was found that Ba, Ca, Cd and Zn tungstate showed good scintillation at room temperature, shortly thereafter, American scholars used the Vemuil method to grow CaWO4 and CdWO4 single crystals, although their light output is lower than that of halide crystals, the density is large and the afterglow is weak, in particular, CdWO4 single crystal has high absorption coefficient of X-ray, good light transmission performance and strong radiation resistance, and is soon used as X-ray fluorescence intensifying screen. With the high energy physics electronic collider accelerator, scintillation detector is widely used to explore the new scintillation crystal and its luminous characteristics once again become a hot spot.

It is worth mentioning that ZnWO4 crystal is a promising scintillator in this field. It has the advantages of high density, high light output and short attenuation time, not easy to deliquescence. It can make up for the shortcomings of traditional scintillator NaI and CsI. At present, ZnWO4 single crystals have been used as scintillation crystals, Cambridge University Cavendish Laboratory, the American Cancer Institute and the German company Siemens are used to make radiometric detector and X-CT probe.

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How To Purify Water by Nano Tungsten Trioxide

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.

nano tungsten trioxide water quality purification image

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 TiO2, ZnO, Fe2O3, CdS and WO3. The results show that WO3 has good photocatalytic stability and is an ideal catalyst for photocatalytic degradation of pollutants in water.

In the wastewater treatment, in 1985, some scholars first reported to WO3 as a photocatalyst treatment of printing and dyeing wastewater experiments, the results show that: When the visible light is irradiated onto the semiconductor powder suspended in the aqueous solution, the dye is decomposed into CO2, H2O, N2, etc., thereby reducing COD and chroma. In order to improve the COD and chroma removal rate of printing and dyeing wastewater, there are three kinds of hollow spherical WO3H2O prepared by using citric acid as structural adjusting agent, there are scholars using citric acid as a structural regulator to prepare three-dimensional hollow spherical WO3H2O. When applied to photocatalytic degradation of organic dyes, visible light irradiation, can be decomposed 94.8% RHB dye molecules.

Nano tungsten trioxide have several key factors photocatalys: (1) Nanostructured materials provide the appropriate surface area to volume ratio; (2) The band gap energy of the lower valence band can be effectively utilized in the visible region of the solar light; (3) The appropriate band gap structure can make the sample more favorable to the redox reaction; (4) The stability of the material, so as to endure the harsh operating environment, therefore, in recent years, more and more researches have been done on the degradation of organic pollutants by WO3 photocatalytic oxidation at home and abroad.

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How Does Nano Tungsten Trioxide Purify The Air

With the growing awareness of environmental protection and recycling of resources, more and more researches are being made on the degradation of organic pollutants.

nano tungsten trioxide air purification image

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, WO3 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, WO3 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 provide the appropriate surface area to volume ratio; (2) A relatively low valence band energy forbidden band gap, so as to effectively use sunlight in the visible region; (3) The appropriate band gap structure can make the sample more favorable to the redox reaction; (4) The stability of the material, so as to endure the harsh operating environment.

In the field of air purification, nano tungsten trioxide can be directly used in the air as oxygen oxidants, effectively decompose indoor and outdoor organic pollutants, and oxidation to remove nitrogen oxides in the atmosphere, sulfides and various types of odor, etc., the reaction condition is gentle, is a very convenient air purification technology, so tungsten trioxide is an ideal choice for air purification machine raw materials.

If you have any inquiry of tungsten, please feel free to contact us:
Tel.: +86 592 5129696/+86 592 5129595
Fax: +86 592 5129797

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