Effect of Powder Property on Tungsten Copper Electrode Density (2 of 2)
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- Category: Tungsten Information
- Published on Monday, 11 January 2016 17:40
- Written by xiaobin
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Relevant foreign scholars have studied the densification process high-density tungsten alloy found W-Ni-Fe high density alloys, when the average particle size of the tungsten particles is 1μm, occurred at about 1200 ℃ rapid densification; when the tungsten particles have an average particle size of 5μm, at 1400 ℃ was undergoing rapid densification. It indicates that decreasing the granularity of powder and increasing the superficial area can remarkably decrease the sintering temperature of powder press.
In addition, the appearance of powder particles has an influence of densification processing. If the shape of the powder particles exhibit uneven shape it is easy to bypass the formation of voids between the particles and increases the friction powder and die wall, between the powder particles, which will not help to improve the sintered density after the bulk material. The higher the degree of spherical particles, the better mobility, it is easily to fill the cavity so that bulk density, but also conducive to pressing and sintering, to obtain a higher density. Nano tungsten powder and nano copper powder SEM image as follow:
Viewed from the SEM image, we can find that micro Cu powder particle has more regular shape and high sphericity; compared with micro Cu powder, micro W powder particle is more irregular, it is polygonal and has low sphericity, which is not beneficial for tungsten copper electrode with high density manufacturing. Furthermore, micron tungsten powder and copper powder having a large surface area and the ratio of the excess surface energy, in a state of energy imbalance, has a high activity, favor the sintering process. Cu particles has good plasticity and soft texture, easily deformed during pressing and help to increase the contact area between the particles so that the tungsten copper electrode material density may be improved; however, W particles has high melting point, high hardness, low plasticity, it is not easily to be out of shape and fractured, which is not beneficial for the density improving.
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Multi-Dimensional Network Structure Tungsten Trioxide Preparation
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- Category: Tungsten Information
- Published on Monday, 11 January 2016 17:38
- Written by qiongyao
- Hits: 237
At present, people have been able to prepare different pore sizes of porous tungsten oxide and have been prepared using a variety of methods and materials that containing a large hole, mesoporous and microporous, or only two of the pore size. These materials have important applications in catalysis, selective separation and sensors; however, the porous material with a foam shape is generally more fragile and friable. Tungsten trioxide is a transition metal oxide that is widely studied because of its unique properties. In addition, the doping tungsten trioxide complex also has a catalytic effect. It means that tungsten trioxide morphology and structure of the desired application function has a direct relationship.
Steps:
Preparing dimensional network structure WO3 containing mesopores by concentrating hydrogen peroxide (H2O2), methanol, over-acid and polyvinylpyrrolidone (PVP) solution. Preparing WO3 mesh structure by using optical microscopy, scanning electron microscopy (SEM), powder X- ray diffraction (XRD), thermal gravimetric analysis (TG), high-resolution transmission electron microscope (HRTEM) and N2 adsorption isotherms (BET) technology after firing.
Conclusions:
1. Optical microscopy and SEM photograph show this shape of the foam cube mesh structure regardless of WO3 is relatively stable before calcination or after calcination, supported by the nature of the performance.
2. Magnified SEM image shows that the wall mesh structure is assembled from nanoparticles made of WO3 after calcination.
3. XRD diffraction analysis shows that WO3 is amorphous foam before calcination, and is orthorhombic crystals after calcination. As PVP structure, it has the advantage of inducing inexpensive agents and stable solution.
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Roughing in Wolframite Beneficiation Processing
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- Category: Tungsten Information
- Published on Monday, 11 January 2016 16:48
- Written by xinyi
- Hits: 246

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New Types, Structure of Coated Cemented Carbide—Diamond Coating 2 of 3
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- Category: Tungsten Information
- Published on Monday, 11 January 2016 17:37
- Written by xiaobin
- Hits: 247
Take YG6 tungsten carbide drawing die as an example, it deposits diamond coating (10-30pm crystalline diamond coating) on tungsten carbide drawing die matrix by chemical vapor deposition (CVD) and the finished products after polishing, finishing and some after processing. In general, the processes of tungsten carbide drawing die with diamond coating are tungsten carbide matrix milling → matrix washing → pre-processing → pretreatment → put in furnace → diamond coating deposited → film testing → finishing and polishing → finished product.
First of all, choose YG6 tungsten carbide die (the shape and size should be similar to the finished product). Then bore milling and finishing for proper shape, and reserve the size margin about 30μm to cooperate with the thickness of the coating layer. Afterwards, it adapts sand blast to eliminate the impurities and loose material of the surface, which can achieve good roughness. After sand blasting, it should be ultrasonic cleaning by distilled water and alcohol. Finally, the drawing die corroded by the acid or alkali prepared and ultrasonic cleaning by distilled water and alcohol again. When the preparation complete, put tungsten carbide drawing die into the equipment of CVD diamond coating deposited.
The most common equipment of coating deposited is hot wire furnace, which is equivalent to a reaction chamber. the gas containing other elements constituting the respective film gaseous reactant vapor or liquid reactants and reaction necessary introduced into the reaction chamber. That is, after the pre-pass hydrogen H2 and methane, CH4, hot filament heated to 2500 ℃, by adjusting the filament temperature, gas pressure, gas flow rate and relevant process parameters, so that the mold surface of diamond film deposition of a certain thickness. There are special requirements for accuracy or surface finish can be achieved by further optimizing the surface quality of the finishing and polishing process precision, to meet different working environment for the corresponding requirements of the mold.
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Wolframite Beneficiation Processing
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- Category: Tungsten Information
- Published on Monday, 11 January 2016 16:40
- Written by xinyi
- Hits: 267

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