Using blue tungsten oxide producing tungsten powder is generally taken the ammonium paratungstate or tungsten trioxide as raw material by weak hydrogen reduction. Blue tungsten oxide particle size is not a important factors in determining the tungsten powder particle size. The hydrogen reduction process of tungsten blue is the ultimate effect in determining tungsten powder particle size. Different reduction process parameters of blue tungsten oxide hydrogen reduction method will lead to different tungsten powder particle size and specific surface area. Because in the whole process of the blue tungsten to tungsten is chemical vapor migration, so the intermediate phase can form a relatively complete small faceted surface crystals.

Crystal formation and size depends on the speed of the water vapor formed and the speed of discharged from the difference material layer. So the water vapor concentration has a significant impact on the tungsten powder particle size. It is shown that when temperature lower than 600 ℃ and leading in small humidity hydrogen make reduction reaction, it will producing finer tungsten powder. Therefore, when using hydrogen reduction of blue tungsten oxide producing fine tungsten powder should be strictly controlled reduction process conditions.

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Tungsten target is also known as tungsten sputtering target. It owns high melting point, elasticity, low coefficient of thermal expansion, resistivity and fine heat stability and other properties. And it has been widely applied in electrical industries, chemical equipment (X-Ray tube, thin-film material, semi-conductor integrated circuit), medical equipment, smelting equipment, rare earth smelting, aerospace and many other fields.
Tungsten target implies an X-Ray tube where high energy electrons are directed in a vacuum to strike a tungsten target. Where the electrons strike the tungsten very short wavelength X-rays are generated and pass out through the vacuum tube for use in medical diagnosis and engineering radiography of welds and castings etc. Tungsten has a very high melting point but it is nevertheless melted where the beam strikes for this reason the target is rotated to give a fresh target surface very frequently and the tungsten target is a fairly thin plate welded or brazed onto a water-cooled copper backing. Less than 1% of the electrical energy delivered into the X-ray tube comes out as X-rays; the other 99% is waste heat. Tungsten is chosen for the short wavelength and penetrating power of it's characteristic 

 

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The study found that the calcine temperature for blue tungsten oxide fisher particle size has little effect. It is generally believed that during calcine process due to stress crystals and crystal phase change weight, resulting in cracks or broken into particles of irregular particles, but basically maintained the original APT particle dimensions. Blue tungsten fisher particle size only reflect the particle size dimensions, closely related to APT particle, blue tungsten fisher particle size therefore determined by the APT particle size.

 In-phase component ATB and W20O58 which has different size，at 800 ℃ condition reducing found blue tungsten oxide fisher particle size has a significant impact on  the reduction of tungsten powder. In the case of blue tungsten surface area substantially the same situation, W20O58 phase component blue tungsten oxide fisher particle size from 7.9um to 12.94um, tungsten powder particle size is reduced from 1.7um to 0.99um. The ATB phase component blue tungsten fisher particle size from 6.22um increase to the 14.00um, the tungsten powder particle fisher particle size from 1.25um down to 1.12um.

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Tungsten powder is an important raw material for cemented carbide making. The large crystal grain size will cause cracks or breakage during use carbide. The large crystal grain size is mainly crease by coarse tungsten powder particles.

Therefore, in order to improve the performance of cemented carbide tungsten powder producing becomes very important process. Tungsten powder for the preparation becomes even more important. Blue tungsten oxide producing tungsten powder continues to mature, and is widely used in industry. Currently circulating reducing blue tungsten oxide method to control tungsten powder particle size has been widespread concern.

Firstly blue tungsten obtained from calcine extra virgin ammonium paratungstic in argon, and then after that we found the blue tungsten oxide particle size distribution uneven and also there has large cracks on the practical, but the cracks in favor of hydrogen into the interior of blue tungsten and make reduction which provides favorable conditions for refine tungsten powder particle size. The first time for Blue tungsten oxide reduction we cam obtain tungsten powder particle size between 5-15um. The first reduction of tungsten powder oxidized in the air became tungsten trioxide, and then making a second time reduction which we get tungsten powder particle size between 3-10um. From this we can see that the tungsten powder particle size reduction through the loop once and oxide twice was significantly better than using blue tungsten oxide reduction of tungsten powder for only once.

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Tungsten target is also known as tungsten sputtering target. With high melting point, elasticity, low coefficient of thermal expansion, resistivity and fine heat stability, pure tungsten and tungsten alloy targets are widely applied in electrical industries (such as, LED and LCD), chemical equipment (X-Ray tube, thin-film material, semiconductor integrated circuit, two-dimensional display, solar photovoltaic and surface engineering.), medical equipment, smelting equipment, rare earth smelting, aerospace and many other fields.
Now a new way-PVD (physical vapor deposition) has been used to sputter thin-film material. The product made in this way owns high density, smooth surface, no stratification, no double skin, no crack and no impurity and good adhesiveness. And with the growth demand of high pure metal and alloy targets, the magnetron sputtering techniques has been widely applied. It can work with both older sputtering devises as well as the latest process equipments, such as large area coating for solar energy or fuel cells and flip-chip applications.

 

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Blue tungsten oxide is widely used in industrial processes mainly because of blue tungsten has many advantages such as high chemical activity, good doping effect, large surface area, reducing efficiency. China added K, Si, AI and other alkali metal oxides to produce tungsten wire is applied from the mid-1970s to the present.

But using blue tungsten oxide technology manufacture tungsten wire not only require a lot of money and equipment, and it also will bring great problems at repression which will cause tungsten blanks low yield, increased production costs. At the part of adding blue tungsten oxide pickling process will produce Hydrofluoric acid and it will lead to contamination the environment. So that subsequent processing pickling process more complex.

From the process is applied to the industries to now it has being developed and improved, for example, controlling the temperature when APT reduction the blue tungsten, tungsten powder ingredients doped est.. At present, the process has been able to meet the needs of electric light source industry basically. And not-acid washing of blue tungsten oxide process has also made a great progress, so that the improvement of the quality of tungsten blanks, decrease production costs.

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While applying tungsten carbide wood cutting tools to deal with cutting of wood products, the relevant temperatures would likely to affect the type of wear mechanisms, and which also shows the tendency of breaking out high temperature oxidation of cobalt. Although some researchers argued that the temperatures measured during woodcutting are not high enough to cause oxidation of the tungsten carbide grains and the oxidation of cobalt occurs in air over a wide range of temperatures above ambient temperature and that the oxidation rate is very low, below 700°C . The differing opinions on this mechanism is mainly due to the inability to directly measure the temperature at the cutting edge and possibly also due to the type of micro-analytical methods used to examine the worn surfaces. X-ray photon spectroscopy (XPS) is a good technique which can be used in the determination of oxides. However, this method has rarely been used and thus the type of reactions and mechanisms caused predominantly by the cutting temperatures remain unclear.

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The quantity and the extractives’ chemical nature, are the vial factors that may influence tungsten carbide cutting tool wear rate, in natural wood. Some acids, for example tannic and acetic, which occur in wood and depending on the moisture content of the wood, these acids can lead to corrosion of the tool during cutting, adding to the overall tool degradation. It is thus expected that the wear rates for cutting green woods would be higher than those for cured woods, since the moisture content is higher in the green woods.

If adopts the tool metal forms chelation reactions with the extractives present in the wood. It is known that most metals form chelation reactions, thus the probability of a metal forming chelates with wood is suppose to be high. The chemical properties of iron and cobalt are known to be similar, so it is expected that cobalt will undergo chelation with the extractives as readily as iron, leading to increasing wear rates. The chelation of tungsten carbide is difficult to predict.It was also found that the wear rate increased with increasing binder volume fraction, an increase in the normal rubbing
force and an increase in the carbide particle size.


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When applying tungsten carbide cutting tools in natural wood cutting processes, a fast increase in power consumption and surface roughness is indicated.



Specially if the natural wood is wet Western Red Cedar, within 15 minutes, the tungsten carbide cutting tools blunt would occur. The tests of the reactivity of cobalt and tungsten carbide in solutions of Western Red Cedar extractives at temperatures of 20°C and 60°C showed that the cobalt binder is preferentially attacked while the carbide grains remained relatively unaffected since they retained their sharp edges. The corrosive nature was found to be temperature dependent where the metals lost 35% more weight at 60°C than at 20°C. This indicates that the increase in temperature accelerated the dissolution process and may control the rate of chelation. Both worn and unworn tool inserts were investigated and the unworn carbide inserts showed very little dissolution of the carbides, while the worn inserts showed a higher amount of carbide dissolution. This indicates that lattice damage due to wear facilitates chemical access resulting in higher wear rates. They further proposed that carbide grains are held in position by the cobalt and when this cobalt is removed then the carbide grains either fall out or are removed.

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The intense contact will be generated between tungsten carbide woodcutting tool and wood, during the wood cutting processes, and the high temperature and stresses are also involves. As hardness, toughness and chemical stability would change with increasing temperature, cutting temperature is a vital factor.



Many previous experimental investigations has been set up to discuss the problem of determining tungsten carbide tools’ cutting temperature and how to theoretically to calculate it. It is likely that the accuracy of the calculation depends on the assumptions made concerning boundary conditions and the proportion of the cutting energy which is converted into heat at the tool/wood interface. The cutting tool temperature is dependent on factors such as speed, feed rate, depth of cut and wood type, with speed being the most important.

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