Ammonium Metatungstate Example in Oligomerization Process Producing Synthetic Lubricants
- Category: Tungsten Information
- Published on 25 February 2016

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Thermal Study on Electrospun Polyvinylpyrrolidone/Ammonium Metatungstate Nanofibers
- Category: Tungsten Information
- Published on 25 February 2016
When a too high heating rate and heating temperature (10 °C min−1, 600 °C) were used, the WO3 nanofibers completely disintegrated. At lower heating rate but too high temperature (1 °C min−1, 600 °C), the fibers broke into rods. If the heating rate was adequate, but the annealing temperature was too low (1 °C min−1, 500 °C), the nanofiber morphology was excellent, but the sample was less crystalline. When the optimal heating rate and temperature (1 °C min−1, 550 °C) were applied, WO3 nanofibers with excellent morphology (250 nm thick and tens of micrometer long nanofibers, which consisted of 20–80 nm particles) and crystallinity (monoclinic WO3) were obtained. The FTIR and Raman measurements confirmed that with these heating parameters the organic matter was effectively removed from the nanofibers and monoclinic WO3 was present in a highly crystalline and ordered form.
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Tungsten Carbide – Polycrystalline Diamond Buttons (2/2)
- Category: Tungsten Information
- Published on 25 February 2016
Foreign scholars also try to use as cubic boron nitride carbide substrate and the buffer layer between the polycrystalline diamond layer having a volume ratio of 1 (CBN): 4 (polycrystalline diamond). The coefficient of thermal expansion of CBN at high temperatures between polycrystalline diamond and tungsten carbide, which effectively reduces the thermal stresses between them, and this excellent compatibility also reduces thermal stress micro-cracks caused by greatly enhancing the impact toughness of the composite buttons. Domestic research agencies by reducing the synthesis of polycrystalline diamond binder content, while increasing the pressure and increase the baking time between making polycrystalline diamond particles are bonded D - D chemical bond is increased, thereby increasing tungsten carbide - polycrystalline diamond compact buttons impact resistance.
D – D is a kind of chemical bond, which has higher binding strength than the physical strength of binder and the higher binding strength, the better impacting resistance. In addition, added polycrystalline diamond sintering process nickel-based or titanium-based additive, which has good wettability of polycrystalline diamond particles, can cover around the polycrystalline diamond particles in the sintering process, prompting more polycrystalline diamond melting the particles more conducive D-D bond combination.
American scholars designed a double polycrystalline diamond composite sheet, the outermost layer of polycrystalline diamond using coarse particles, with high impact resistance; and the inner layer using fine diamond particles, effectively improve the wear resistance. The inner layer of diamond, cobalt Co incorporated as a sintering agent, the outer layer of the coarse grain diamonds contain less or no cobalt; during sintering process, cobalt (Co) by the formula sweep extended through the inner layer to the outer layer of the fine particles of rough diamond grain diamond layer. Due to fine-grained diamond layer as the substrate, it has uniform distribution in the process of sintering and avoids undersintering and softening caused by Co distributed unevenly.
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Tungsten Carbide – Polycrystalline Diamond Buttons (1/2)
- Category: Tungsten Information
- Published on 25 February 2016
Tungsten carbide buttons have higher hardness and excellent impact ductility, which can be widely used in DTH drills for some rock drilling or impact rotary drilling operations. Based on the impact energy supplied by mud pumps, DTH drill uses buttons on the surface of the bit for rock drilling, which drilling depth up to 1000 meters or more, can be achieved in deep drilling and crushing complex formation, so it has strict mechanical properties to tungsten carbide buttons, especially impact resistance. But in some hard abrasive rock drilling, tungsten carbide buttons will be wore easily and leading to failure. Therefore, the process of tungsten carbide button with coatings has come into being.
Tungsten carbide – polycrystalline diamond buttons is a kind of new process, it uses tungsten carbide as substrate and coated with polycrystalline diamond. Tungsten carbide play a supportive role for the polycrystalline diamond, carbide and polycrystalline diamond has a higher hardness and wear resistance, but its impact resistance is lower, which has also become the focus of research related to researchers. In order to improve the impact toughness of tungsten carbide – polycrystalline diamond buttons, foreign researchers have proposed a functionally graded structure composite buttons, carbide diamond layer that is applied between the cemented carbide substrate and the polycrystalline diamond layer the buffer layer can effectively reduce internal stress between the polycrystalline diamond layer and the cemented carbide substrate; Or using polycrystalline silicon or silicon alloy diamond thermal expansion coefficient is closer to penetrate into the pores of pickled diamond, the experiments show that polycrystalline diamond toughness and fracture resistance capacity has been more significant improvement.

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Ammonium Paratungstate Preparing Tungsten Rod 2/2
- Category: Tungsten Information
- Published on 25 February 2016
Remarks:
1) The process conditions supposed to be: The temperature in the blue tungsten One-Reduction process may be: 530, 550, 580, 620, 650, 670℃, and the flow rate of hydrogen is 2.0~3.0m3/h, also the dew point is less than or equal to 60℃, boat loading amount is 300~350g, and the tungsten dioxide output will contain oxygen at rare of 12~14%;
2) The conditions of Secondary-Reduction are like bellows: temperature of 700, 750, 800, 830, 860, 860℃, the flow rate of hydrogen is 3.0~5.0 m3/h, the dew point is less than or equal to 60℃, boat loading amount is 280~320g.
5. Pickling
Washing the fine, medium and coarse tungsten powder respectively with the 5~6% concentration of hydrochloric acid and hydrofluoric acid to remove impurity;
6. Mix powders
Mix fine, medium and coarse tungsten carbide powder at the ratio of 20~25:50~60:20~25 in a mixer for 25 ~ 30min;
7. Forming at the condition of cold isostatic pressing
8. Sintering at high temperature
Sintering the tungsten billets which is pre-sintered in a vertical melting machine under the protection of hydrogen, set a certain conditions, then we get the tungsten which is needed.
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Ammonium Paratungstate Preparing Tungsten Rod 1/2
- Category: Tungsten Information
- Published on 25 February 2016
Tungsten Halogen Lamps is mainly applied in the lighting system of automotive, electronic and aerospace industry. Due to the special using environment in which the shock and vibration presence, thus the core materials-tungsten filaments is required to be with good recrystallized of dovetail joint structure, also the ratio of length and width is supposed to larger than 12, which means it has the good properties of sagging resistance at high temperature and deformation resistance. Therefore, improving the properties of tungsten bars which can improve the quality of Tungsten Halogen Lamps has become extremely urgent. A literature has proposed a method for preparing tungsten rod with good properties of sagging resistance at high temperature and deformation resistance which can applied in the production of Tungsten Halogen Lamps.
The specific steps are as follows:
1. Mix monoclinic and spherical ammonium paratungstate by the ratio of 3:1~1.5, as the raw materials;
2. Pre-reduction
Make the raw material going through a reducing furnace with four temperature zone, reduction to generate blue tungsten oxide at the hydrogen atmosphere;
3. High Potassium doping
Mix the blue tungsten oxide into a solution containing with potassium silicate and aluminum nitrate;
4. Reduction
1) Using Secondary-Reduction to generate fine grain tungsten powder with FSSS 2.0~2.6um from doped blue tungsten;
2) Generate coarse tungsten powder with FSSS 3.4~4.0um by One-Reduction method;
3) Generate medium grain tungsten powder with FSSS 2.7~3.3 um in a six temperature zone furnace by Secondary-Reduction method;
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SEM Technique Analyzing Tungsten Trioxide Nanowire
- Category: Tungsten Information
- Published on 25 February 2016
Structural Equation Modeling is a blend of multivariate statistical techniques of factor analysis and path analysis. Its strength lies in the quantitative study of the interactive relations among multiple variables. In nearly three decades, SEM is used in a large number of social and behavioral sciences, in the recent years; it has been increasingly used in market research. By SEM technique analyze of tungsten trioxide nanowire, we have a better understand that the impact of changes in external factors caused by the topography. It can be analyzed by the precursor and the reaction temperature.
Nanowires may be defined as having in the transverse direction that is limited to one-dimensional structure at 100 nm (without longitudinal limit). Nanowire suspension means the end of the nanowire under vacuum. Depending on the composition of the material, the nanowire can be divided into different types, including metallic nanowires, nanowires and the insulator semiconductor nanowires.
The preparation of tungsten trioxide nanowire can be divided in three steps. Firstly, obtaining the diameter about 200-500nm tungsten trioxide nanowire, the length about 5-10μu with 1.3g of sodium tungstate reaction in the same conditions. Secondly, we can also study its effect on the appearance of the tungsten trioxide nanowires synthesized by controlling the reaction temperature. Finally, we obtain tungsten trioxide nanowires in the uniform conditions that the reaction time is 32h at 240 ℃, and its diameter is 200-500nm, its length is about 5-10μm.
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Preparing Tungsten Trioxide Fiber
- Category: Tungsten Information
- Published on 25 February 2016
Fiber refers to the material from continuous or discontinuous filaments thereof. In plants and animals, fiber plays an important role in maintaining organizations. Fibers can be woven into thin, thread and twine, paper or fabric woven fibrous mat; fibers are also used to manufacture materials, and other materials to form composite material. Natural fibers are naturally occurring, we can get fiber naturally, and fibers are divided into different types according to their origins, animal fibers, plant fibers and mineral fibers. In addition, there are chemical fibers, synthetic fibers, synthetic fibers, inorganic fibers and the like. Filling fibers can effectively improve the strength and rigidity of the plastic, reinforce plastic rigid structure.
Tubular tungsten trioxide nano fibers can be used to make gas sensors with high sensitivity and good stability; it shows a bright prospect in the field of gas sensor. Tubular tungsten trioxide fibers can be prepared by template method that has good controllability. This method can use its space limitations and the role of template debugging effect to control the size, morphology, structure and arrangement of the synthetic material.
Making tungstic acid as source of tungsten, placing tungsten acid in the container, and adding the container to the hydrogen peroxide and ethanol, and stirring constantly; immersing AAO template in tungsten trioxide sol about 30min, then rinsing with demonized water, and placing it about 30min in the air, and heating it at 550 ℃ for 6h in the environment, drying it, finally we can obtain similar tubular fiber tungsten trioxide .
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AMT / SiO2 Catalyst Characterization Results
- Category: Tungsten Information
- Published on 24 February 2016
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Producing Crystalline Ammonium Metatungstate Method
- Category: Tungsten Information
- Published on 24 February 2016

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