Tungsten Oxide Nano Flower Surface Barrier Model

Tungsten oxide picture

Due to the presence of contact junctions in tungsten oxide nanoflowers, nanostructures that cross each other have different atomic adsorptions and thus different surface electronic states. Different surface states of electrons will form different surface potentials and a surface barrier appears at their contact junctions.

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Growth Mechanism of Tungsten Oxide Nano Flower

Tungsten oxide picture

When the temperature is gradually raised above 800 ° C, tungsten will not be evaporated because the melting point of tungsten is 3420 ° C. While the tungsten oxide has a boiling point of 800 ° C, the tungsten oxide will sublimate to vapor tungsten oxide. At the same time, it will follow the gas-solid reaction model model, tungsten oxide nano flower structure growth mechanism is as follows:

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Cemented Carbide Special-Shaped Powder Proportioning Sintering Program

cemented carbide sintering image

In general, the HRC hardness of tungsten based cemented carbide is between 24~32, and at present the market needs tungsten based alloy products with high hardness special-shaped parts or plates, the hardness of HRC alloy for more than 35, now can only rely on the forging deformation treatment the hardness, but the complexity of the production process, equipment investment, the production cost is high, the profit is very low, the lack of market competitiveness;

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Extraction of Violet Tungsten with Ammonium Metatungstate Evaporation Reduction

violet tungsten extraction image

As a semiconductor material (its band gap can be 2.4 to 2.8eV), tungsten oxide is widely used in photoelectrochemistry. The violet tungsten WO2.72 has been paid special attention to by the researchers because of its unique properties and structures.

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Sintering Shrinkage of Tungsten Carbide

different contraction stages image
During the process of sintering, the tungsten carbide press will produce obvious contraction, which is the sintering densification of tungsten carbide. Similar to the densification process, the contraction process can also be divided into three stages, and the contraction and contraction mechanisms at each stage are not the same.

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Sintering: Evaporation - Condensation

kinetic equation of sintering evaporation condensation image
In the sintering process of tungsten carbide, material migration is usually accompanied. At high temperature, the phenomenon of material evaporation from particle surface to space may also occur during sintering, which has a direct effect on densification and pore change of sintering. Therefore, sintering power can also be studied from the angle of the evaporation-condensation of the material, that is, the difference of the saturated vapor pressure is used to express the sintering power.

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Effect of Heating Rate on Sintering Shrinkage

heating rate image
Sintering shrinkage of tungsten carbide is a very prominent change during the sintering process. As the amount of shrinkage is directly related to the properties of the alloy, size and other key indicators, it is necessary to strictly control the amount of shrinkage. The shrinkage of tungsten carbide is mainly in the two processes of solid phase sintering and liquid phase sintering.

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Effect of Grain Size on Sintering Densification

hole of tungsten carbide image
The sintering of tungsten carbide is a kind of liquid phase sintering. The wettability of liquid phase, the solubility of solid phase in the liquid phase and the quantity of liquid phase are three basic conditions of liquid phase sintering, which are also the basic factors.

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Tungsten Carbide Direct Reduction and Carbonization Technology

tungsten carbide electron microscope image

The ultrafine cemented carbide made of ultrafine tungsten carbide powder has the characteristics of high strength and high hardness. It effectively solves the contradiction between hardness and strength of traditional cemented carbide, widely used in the production of integrated circuit board micro drill, dot matrix printer print needle, precision mould, tool, woodworking tools, medical drill etc..

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Preparation of Composite Photocatalyst with Copper Doped Violet Tungsten Oxide

violet tungsten oxide electron microscope image

Tungsten catalyst in a large number of materials, with special surface structure of violet  tungsten oxide, oxygen defect structure of high chemical activity and high concentration, and in the ultraviolet has a high degree of absorption, at the same time, research shows that copper as doping elements can improve the catalyst in the visible light response range. Therefore, the selection of copper doped violet tungsten as a photocatalytic material has a good application prospect.

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