Currently, there are there methods for synthesis tungsten hexafluoride which are common used. The first is by direct reaction of fluorine gas and tungsten to generate tungsten hexafluoride. The second is tungsten and nitrogen trifluoride (NF3) direct reaction to produce tungsten hexafluoride. The third method is to generate tungsten hexafluoride by react halogen, tungsten and HF. The following is introducing the reaction of using tungsten and nitrogen trifluoride to produce tungsten hexafluoride and in this reaction NF3 as fluorinating agent.
The reaction equations of tungsten and nitrogen trifluoride reaction is as follows: W + 2NF3 - WF6 + 3N2, the reaction conditions at temperatures greater than 400 ℃ decomposition of NF3 to produce F2. F2 reacts with the metal to generate tungsten hexafluoride. Besides the NF3 moisture content which used in reaction direct related to the purity of the product. That is need high-purity NF3 to produce tungsten hexafluoride. But the high-purity NF3 requires cryogenic condensation method to cool NF3 at -130℃~ -70℃, after water solidified to separate to make it. What’s more the reactor should make by nickel or monel. But this will lead to increased production costs, and a higher investment risk, which are not suitable for applied industrial production.

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Produce tungsten powder usually by reducing tungsten oxide which restored ammonium paratungstate or tungsten trioxide by hydrogen. And the reaction is usually carried out in electric tube furnace or rotary furnace. Using hydrogen reaction method to produce tungsten powder there are two important processes, the first is at a temperature of 500℃-700℃ restore tungsten trioxide to tungsten dioxide. And the second is at 700℃-900℃ temperature, tungsten dioxide is reduced to tungsten powder. What’s more tungsten powder good properties (such as purity, particle size, size distribution, etc.) depends on the reduction process, such as the reduction temperature, boat load of tungsten oxide, boat speed, flow rate of hydrogen and hydrogen water content. In addition, using aluminum, calcium, zinc and others to restore tungsten powder also caused a big concern.
Except using hydrogen reaction method to produce tungsten powder, in the early time also using tungsten oxide carbon reduction method to restore tungsten powder which is at the temperature above 1050 ℃. But this method will produce low-purity tungsten powder, so there is less use in industry.

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Tungsten hexafluoride is a strong fluorinating agent, with the exception of nickel, monel and stainless steel, make many metal fluoride at room temperature. In the dry state it has low corrode for glass, but able to respond quickly in heavy moisture. Tungsten hexafluoride and ionic halide react can form complex compound at a high temperature to reduce tungsten by hydrogen.
There are three methods for synthesis of tungsten hexafluoride, is described below using fluorine gas as the fluorinating agent in the process to produce tungsten hexafluoride: making tungsten and fluorine gas (F2) direct reaction to synthesis tungsten hexafluoride, in order to prevent the erosion container wall of fluorine, the reaction vessel material should be monel, nickel or stainless steel. Chemical reaction equation is as follows: W + 3F2 - WF6.
This reaction is carried out under the conditions of 400 ℃, tungsten direct reacts with F2 to  produce tungsten hexafluoride, because the nature of F2 is too lively, in order to make the reaction proceed smoothly requires a certain proportion of nitrogen added. Generally the tungsten metal is added by tungsten powder to make the gas-solid phase contact area as large as possible, and then collect tungsten hexafluoride into another low temperature container by liquid form.

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Tungsten powder restores by hydrogen in four tube muffle furnace where the tungsten oxide as raw material. The particle size of tungsten powder mainly 0.6-3.0um which can be divided into coarse, medium and fine several granularities. Tungsten powder is used to process powder metallurgy of tungsten products and as raw material of tungsten alloy. Tungsten powder can be made into wire, rods, tubes, plates and other processing materials and shaped products. Besides, tungsten powder mixing with other metal powders can be made into a variety of tungsten alloys, such as tungsten and molybdenum alloys, tungsten-rhenium alloy, copper alloy of tungsten and tungsten heavy alloy. And there is another important application of tungsten powder which is used tungsten carbide powder and then uses it to produce carbide tools, such as turning tool, milling cutter, drill and mould.
After many experiments found that the performance of tungsten powder will directly affect the quality of tungsten materials and tungsten powder metallurgy products. Particularly the purity and particle size of tungsten powder affecting products evidently. During the restore reaction, reduction process and raw materials is the main reason for the performance of tungsten powder. Therefore, to produce a good performance of tungsten powder not only to control the reduction process has to choose the good performance of the tungsten oxide raw material.

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