Nanocomposites Tungsten Carbide Prepared from Ammonium Paratungstate 1/2
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- Category: Tungsten Information
- Published on Thursday, 14 January 2016 17:49
- Written by chunyan
- Hits: 284
Nanocomposites material is using resin, rubber, ceramics and metal as continuous phase, and using nanometer sized metal, semiconductor, rigid particles and other inorganic particle, fiber, carbon nanotube modifier as dispersed phase, through appropriate preparation method of modified agent homogeneity of dispersion in the matrix material to form contains nanosize materials of the composite system, also known as nano materials. Carbon nanotube is a kind of ideal modified material, because the properties of high strength, elastic modulus, specific surface area, electrical conductivity, temperature stability and thermal conductivity, low thermal expansion coefficient and good resistance to acid and alkali it has. A method to prepare nanocomposites of tungsten carbide uniform dispersed carbon nanotube in tungsten to achieve mass and universal production. And the original properties of tungsten can remained and also improved.
Principle: Using the adsorption tungsten of carbon nanotube to restore nanocomposites tungsten carbide from ammonium paratungstate in the gas of hydrogen.
Steps as following:
1. Obtaining modified neutral carbon nanotube
Set carbon nanotube in concentrated nitric acid under 65-75℃, ultrasonic dispersion for 20-40min; then heated to 80 to 95℃ and reflux for 1 to 3 hours, after cooling down to room temperature, diluted in ionized water and filtered until the solution become neutral; drying the neutral particles in vacuum environment of 70-85℃ for 1.5 to 3 hours to modify the neutral carbon nanotube.
Remark: 1g carbon nanotube is obtained in 100 ml of concentrated nitric acid.
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Year Of Monkey New Year Celebrating Tungsten Gold-plated Blocks
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- Category: Tungsten Information
- Published on Thursday, 14 January 2016 17:48
- Written by yaqing
- Hits: 272
New Year celebrating culture is a symbiotic culture with national characteristics of the traditional Chinese Spring Festival cultural. For China, a ceremonies country with five thousand years of history and culture, people will come to carry out many forms that full with traditional culture to celebrate the new year. One way is to issue the New Year celebrating gold blocks, this kind of New Year celebrating gold block were mostly carved with the Chinese zodiac, Chinese New Year paintings and some other elements which are full of Chinese characteristics or connotations. 2016 Spring Festival is approaching, the various New Year celebrating gold blocks of the year of Bingshen, or the New Year of the Monkey start selling in major shopping malls and have been sought after by people.
But the high price of gold can not be afforded by many ordinary collectors, based on this, the tungsten gold-plated blocks have the adorable price than gold blocks and the same quality and appearance with gold blocks, which makes tungsten gold-plated blocks welcomed by many ordinary collectors. The New Year celebrating gold-plated tungsten blocks of Year of Monkey are circulating on the market with purpose of celebrating the new year and spreading the traditional Chinese cultures, it can not become the tools for criminals to extort money, or to cheat the customers. Here is to remind consumers, in New Year Spring Festival, when to buy the New Year celebrating gold blocks, please pay more attention to identify the difference between tungsten gold-plated blocks and gold blocks.
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Molybdenum Sulfide Precipitation Separating Tungsten and Molybdenum from Sodium Tungstate Solution Influence
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- Category: Tungsten Information
- Published on Thursday, 14 January 2016 17:40
- Written by linlu
- Hits: 266
It’s an important and urgent problem of realizing tungsten and molybdenum separation from sodium tungstate solution in tungsten and molybdenum metallurgy. Molybdenum sulfide precipitation separating tungsten and molybdenum from sodium tungstate solution achieves good effect. The influence of the experiment shows in the following aspects:
1. One of the key of molybdenum sulfide precipitation separating molybdenum and tungsten is complete degree of molybdenum sulphur generation. The pH of the solution is the main factor affecting sulphur generation effect. The effect of molybdenum sulphur generation reduces with the increase of pH value. After adding sodium sulphide in solution, when pH value is less than 9.0, the Mo/WO3 < 0.02, separation effect of tungsten and molybdenum is good.
2. This experiment solution contains much molybdenum. If vulcanizing agent is excessive, there will be a lot of vulcanizing agent joining the solution. Because tungsten content closes to molybdenum content in the solution, it will inevitably lead to tungsten sulphur generation. Tungsten content in precipitation is higher. As a result, adding amount of sodium sulphide should reduce the tungsten sulphur generation. Because of molybdenum and sulphur generation reaction equilibrium constant is much larger than tungsten sulfide reaction equilibrium constant, plus a high molybdenum concentration in the solution, when adding no more than molybdenum sulphur generation theory for the reaction of sodium sulphide, the reaction of molybdenum sulphur generation will proceed fast. This can more effectively precipitate and remove the molybdenum while tungsten remains in the solution.
3. To remove a small amount of molybdenum in sodium tungstate solution, sulphur generation time can be extended to remove molybdenum. But for this test material, due to the high molybdenum concentration in the solution, molybdenum sulphur generation reaction speed is faster. Within the time range of the test, the time of sulphur generation has no obvious influence on separation effect of tungsten and molybdenum.
Above all, we can draw the following conclusions:
1. By controlling a certain condition, the molybdenum sulfide precipitation can effectively separate tungsten and molybdenum from sodium tungstate solution. After the separation of tungsten and molybdenum by this method, the adjustable acid Mo/WO3 drops to around 0.03. Molybdenum content can reach 35% ~ 44% in the molybdenum sulfide slag andWO3 content is below 2%.
2. Through this method, the recovery rate of tungsten is approximately 88% and the recovery rate of molybdenum is 95%.
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Tungsten Gold-plated Bars Barrel Plating Production Process
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- Category: Tungsten Information
- Published on Thursday, 14 January 2016 17:41
- Written by yaqing
- Hits: 280
Barrel plating is one of the gold electroplating methods, and for tungsten gold-plated, the electroplating is an important gold plating process. So one of the production process of tungsten gold-plated bars is barrel plating. In general, the tungsten products, which use the barrel plating method to have the gold-plating treatment are with small volume. For the larger volumes of tungsten products, they usually use rack plating method. The crafts such as tungsten gold-plated bars, its volume is not large and with a simple shape, so it’s suitable to take barrel plating method.
The common ways of barrel plating include vibration plating, tilting barrel plating and horizontal barrel plating, the differences between these three ways is that they use the different shape and axial direction of barrels. As early as in the late 1940s, China had already appeared the barrel gold-plating. Taking barrel plating process to produce tungsten gold-plated bars, then that is to put the molded tungsten products into the barrel, which has fulled with lot of holes, then the tungsten alloy bars will continuously rotate with the rotation of the barrel after conducting the current, so that can make the gold-plated solution be uniformly distributed on the surface of the tungsten alloy bars. This also means that the holes number, size of barrel wall, the size of the current and tungsten alloy bars will affect the final end products. The barrel plating production process of tungsten gold-plated bars is convenient and easy to operate and does not require too much manual operation thus saving labor, which occupies a very important place in the current electroplating field.
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Molybdenum Sulfide Precipitation Separating Tungsten and Molybdenum from Sodium Tungstate Solution
- Details
- Category: Tungsten Information
- Published on Thursday, 14 January 2016 17:37
- Written by linlu
- Hits: 242
Separation of tungsten and molybdenum has been a big problem of molybdenum and tungsten metallurgy industry. On one hand, China's tungsten resources and high quality tungsten concentrate are fewer and fewer. Tungsten raw materials and tungsten concentrate usually contain molybdenum at different degrees. With growing development of hard alloy, the electron, national defense and other industries, the request for molybdenum content in tungsten products is more and more strict. On the other hand, because of the influence of the lanthanide contraction, tungsten radius is close to molybdenum ionic radius and atomic structure and chemical properties are very similar. Separation process is very difficult. For a long time, people have made a lot of research on separation of tungsten and molybdenum. Methods in industrial application at present basically are molybdenum sulfide precipitation, selective precipitation, ion exchange method, extraction method and so on. In this paper, molybdenum sulfide precipitation separating tungsten and molybdenum from sodium tungstate solution has achieved good effect.
Molybdenum trisulfide is black solid. It will be heated into molybdenum trioxide above 400℃ in air. It’s slightly soluble in cold water and soluble in hot water. When it’s soluble in aqueous sulfide, the sulfide molybdate will be formed. Molybdenum trisulfide is instable. When heat it in vacuum, it will decompose into molybdenum disulfide and sulfur. Synthesis method of molybdenum trisulfide is adding hydrogen sulfide in the molybdate solution.
The basic principle of molybdenum sulfide precipitation separating tungsten and molybdenum from sodium tungstate solution is as follows: Affinity on sulfur of tungsten and molybdenum exist certain differences. Molybdenum acid radical ion will become thiomolybdate preferentially under certain conditions. In the process of adjusting acid, thiomolybdate salt transforms into molybdenum trisulfide precipitation. While most of tungsten reserves in solution, so as to realize the separation.
The experiment method: adjust the solution PH value to 9.0 below and add a certain amount of sodium sulfide. Further adjust the pH of the solution to 8.0 or so and control certain sulfur generation conditions. And then adjust the pH of the solution to around 2.0 ~ 3.0. After boiling, dilute solution double and filter after cooling.
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