Pyrochlore phase tungsten oxide multidimensional channels chemical compound and the formula is M2B2O6O '. It is a special form of tungsten oxide, because it has a molecular sieve mesh structure and dielectric stability, so its chemical and physical characteristics have significant change. Not only conductive properties, adsorption performance enhancements, and in catalysis, sensing, electrochromic and fuel and electromagnetic fields have been widely used. The method of production tungsten oxide pyrochlore phase has: soft chemical synthesis and hydrothermal synthesis. Soft chemical synthesis produce pyrochlore phase tungsten oxide is under mild conditions synthesis by inorganic functional materials. It is in low or solution to make reactant in molecular size can be uniform mixing, and the reaction can be controlled step by step. After producing precursor or intermediate the material which having a composition, structure and morphology has finally produce. The hydrothermal synthesis method is under high temperature conditions, water or other solutions in critical or supercritical state, the reactivity increased physical properties and chemical reactivity in solution occur great changes, is a reflection of different from the norm.

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Bronze phase tungsten oxide is special non-stoichiometric compounds with a general formula is MXWO3 (0 <x <1). Such compounds are more exist in sixty thousand crystal system, cubic crystal system and tetragonal crystal system, its structure is basic on WO6 mention structural layout primitives, tungsten oxide by foot roof structure built into a rigid skeleton having a six-membered, five- or four-membered ring channel layered structure. Such compounds have special physical and chemical properties, which generally has a high electronic conductivity and faster ion transport properties, which can be up to more than the conductive 2.5 × 106Ω-1m-1, is a low-temperature superconductors. Recently it was in the field of electrochromic displays, electrode and PH sensors widely used. The producing methods of it have chemical reduction, electrochemical reduction, and thermal reduction method.

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Using electro-reduction method produce bronze phase tungsten oxide is a common method. Using electrochemical reaction restore WO3 and molten alkali metal tungstate. Generally use carbon as the anode, Pt or CrNi alloy as a cathode, the producing process is expressed as follows: x / 2Na2WO4 + (1-x) WO3 → Na2WO3 + x / 4O2. in sulfuric acid solution electrolytic reduction  WO3 can produce a series of HxWO3 bronze, after that a number of scholars have used WO3 or bronze as electrode material to produce (NH4) 0.3HxWO3, H0.6WO3 and other bronze. Although the method be used widely but high equipment requirements, and greater energy consumption.

There is another method which is using electrochemical produce tungsten bronze phase, and that is ion insertion method. This method is through electric field putting suitable ionic radius into the pores to form tungsten oxide bronze, and it can produce a bronze phase tungsten oxide which has two kind of ions simultaneously existed. This approach can greatly reduce the reaction energy consumption, but also improves the efficiency of the reaction.

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In fact, heat reduction method is the general term of many ways. Using production bronze phase tungsten oxide as example, there are solid - solid state reaction, the solid - molten reaction, gas - solid state reaction, thermal decomposition reaction and hydrothermal dissolution reactions and so on. In addition to hydrothermal and solvothermal reaction method, several other production methods require at higher temperature and reducing atmosphere, and this will inevitably increase the requirements for instruments and high energy consumption, difficult to control the reaction, the reaction process is easy appeared mixed phase. Therefore, it is not the best choice for producing bronze phase tungsten oxide. The hydrothermal and solvothermal synthesis method has many advantages which get more and more people's attention. some researchers using glacial acetic acid and ethylene glycol as a solvent, and in autoclave which having lined stainless steel for 5 days at 200 ℃, the (NH4) 10W12O41 reduced to sixty thousand bronze with (NH4) xWO3.

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Study tungsten oxide photochromic almost half a century, but uncertainty and change color to characterize the unity of the light source chosen their development will be very slow. 1973 Deb use Urbach rule: K (v, T) = K₀exp [-B (E^Ω_g-hv) / KT]. Where hv is radiant energy, B and K₀ is a constant characteristic of the material. When the light energy is more than 3.5eV, the (Khv) ^{L / 2} and hv will be a linear relationship. That K is proportional to (hv-E^Ω_g) ² / hv. Accordingly reasoning greenhouse condition the energy band gap is3.25eV. Because the selection is a suitable light source, it is the key to discoloration. Currently there are reports of high pressure mercury lamp light source and two high-pressure xenon lamps. However, the use of light source wattage vary, mercury has 500w, 400w, 250w, 150w and the like. Xenon lamps have 500w, 200w, 150w, 75w, etc. Although only change the wattage of light intensity, but it reflects the color properties of tungsten oxide. In particular, to meet the different needs from the standpoint of photochromic material when under sunlight sunglasses manufacturers have been the most demand, high-band color and Zeng field of information needed for long-term stable material, and display material aspect requires fast coloring and bleaching properties.

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Tungsten crucible is the product of tungsten. Forging tungsten crucible refers to tungsten crucible is made through unwrought, whose purity can reach to 99.95% and density is up to 19.1g / cm3. Sintering tungsten crucible size is larger than the forging one, it can achieve the maximum diameter of 100mm, a thickness of 5 ~ 12mm, height up to 100mm.

Forging tungsten crucible is mainly used for smelting metals, such as, molten aluminum. Forging tungsten crucible’s density (can reach to 19.1g / cm3) is different from Sintering tungsten crucibles’ (18.2/cm3) in physical properties. Forging tungsten Crucible has a better crystal structure. Because of its high temperature resistance, it can be used as core container of rare earth smelting furnace and other industrial furnace.

Physical properties of forging tungsten crucible:

High purity;

High density;

No internal cracks;

Size precision;

Smooth inner and outer walls.


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Tungsten crucible has the properties of tungsten, wear-resistance, high melting point, high density, corrosion resistance and other properties; therefore, it is often used as a core container for sapphire growth furnace, rare earth smelting furnace, quartz glass melting furnace and other industrial furnace. Tungsten crucible working temperature typically is above 2000 ℃. In particular, for sapphire growth furnace, tungsten crucible with high-density, high purity, size precision, and smooth inner and outer walls and without internal cracks and other properties has played a key role in sapphire crystal growth process, such as, pulling quality control, seed success rate, off crystal stick pan and extend its useful life.


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To improve large-sized tungsten crucible production process, should mix the different thickness of the tungsten powder according to a certain proportion. Use mixed tungsten powder to compacts of large-sized crucible, and then by phased sintering, the sintering process is divided into four stages: sintering neck forming, sintering neck of growth, and the formation of voids and pores reduction and growth. Improved process for producing tungsten crucible can reach to the density of 18.0g / cm3 or more, the size of φ280mm × 400mm, the process is stable and can be mass-produced. Practical application proved that this kind of crucible is suitable for the rare earth metal smelting requirements.


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Geo-logging is a technique widely used to explore for oil and gas deposits. It consists of lowering a gamma source, which is usually located at the end of the drill string, into a bore hole.

A tungsten collimator is used to direct a beam of radiation from the source onto the rock strata. This beam is then reflected back onto detectors which are located higher in the drill string. Data from the detectors can indicate whether or not the rock is likely to contain deposits of oil or gas. Tungsten alloy is also used to shield the sensitive detectors from direct exposure to the radiation from the source. This helps ensure accuracy in the measurements.

The photograph below is the tungsten alloy materials for geo-logging.

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The crucible which is used for IF (Intermediate Frequency) sintering, it is always made of the tungsten material, i.e. tungsten crucible.

Crucible refers to use refractory materials, such as graphite, clay, quartz, tungsten, etc., to make from melt tank or vessel.

In the field of powder metallurgy, IF sintering has been widely used, especially when it is at higher sintering temperature or the process of producing those large work pieces, which is essential for sintering method. Tungsten crucible in the process of IF sintering, should ensure the furnace temperature is even and heating speed is fast. Therefore, tungsten crucible is one of the necessary equipment of intermediate frequency sintering.


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