2015年12月15日星期二

Vacuum Carbon Reduction Method Restoring Tungsten Trioxide

Because of tungsten powder and tungsten carbide powder chemical purity and physical properties has high requirement so producing tungsten powder and tungsten carbide powder process is very complex and the cost is higher too. But tungsten powder composition when not strictly required in most cases where there are a lot of impurities so using industrial pure carbon reduction tungsten powder is an economical and easy way. In a vacuum furnace use carbon reducing tungsten trioxide making high purity tungsten powder and tungsten carbide powder provided by melting and casting. 

According to current science and technology, using industrial pure carbon or tungsten carbide powder as a casting material is fully meet the requirements. Using carbon restore tungsten trioxide is similar with using hydrogen restore tungsten trioxide. At atmospheric pressure, at a temperature condition of 750 ℃ heating tungsten trioxide so it will mix with carbon black or graphite powder occurring reduction. The reaction chemical equation is: WO3 + 3C = W + 3CO, WO3 + 4C = WC + 3CO. The temperature under 1000 ℃, mainly using CO participate in a reaction and chemical equation is: WO3 + 3CO = W + 3CO2, CO2 + C = 2CO. The main process includes milling mixing, compression molding, dried at 200 ℃ temperature, then vacuum carburizing, and then filtered through milling.  



Violet Tungsten Oxide Cycle Reduction to Produce Micro Tungsten Powder

Fine and uniformity tungsten powder are key point for producing carbide, and micron and submicron tungsten carbide powder is useful to producing carbide. According to the relevant academic report found that single tungsten oxide can produce submicron or micron tungsten powder. Using violet tungsten oxide (VTO) producing fine tungsten oxide not only the process of it is simple as well as process parameters are easy to control and also equipment are not complex etc. Producing process as follows:

1. VTO were first reduction in hydrogen, along a first temperature of 640 ℃, the second temperature of 760 ℃, third temperature of 860 ℃, when the temperature reaches 860 ℃ heat preservation for 20min.

2. in the air at 500 ℃ making tungsten powder to oxidation with slowly heated for the first time, then heat preservation for 10min.

3. Replace the first step and second to continuous cycle reduction reaction.

4. Using alcohol on the analytical results above steps were dispersed pattern, then using BT-9600 laser particle size analyzer and JXA-840A electron probe scanner to analysis particle size and morphology of samples.



Tungsten Trioxide Films

Tungsten trioxide film is a new type of functional material, which has a wide range of applications in smart windows, a large area flat-panel displays, gas sensor, and so on the field. But because WO3 Films still have some shortcomings, such as discoloration and sensitivity is not high, it will cause a lot of restrictions in the application. In order to improve its performance so that it can be widely used, the optimization can generally divided into three kinds: one is preparing a novel surface topography WO3 film.

The second is the preparation of nanometer WO3 composite film, third film doped WO3 modified. With further research to expand, need to find new chemicals, new fetters, explore preparation skills and preparation parameters appropriate to improve the surface appearance of the film become a hot topic. Currently, for performance optimization WO3 film discoloration research focused on electrochromic and temperament discoloration. And to improve its photochromic,less heat to research color and other properties. Future research in this area can be expanded.




Violet Tungsten Oxide Production Manufacture Process


Violet tungsten oxide using the APT as raw materials,which is during at the closed furnace in the industry. Under certain conditions, adding NH3 during calcination, and the NH3 will decompose H2 and N2, it will form a wet hydrogen atmosphere furnace in the stove, so that APT under mild reducing atmosphere, gradually decompose, generating purple oxide reduction. 

There are many factors in the process of preparing violet tungsten, one by the hydrogen reduction of tungsten oxide mechanisms apparent hydrogen greater humidity, the temperature required to obtain the higher tungsten purple, so choose the calcination temperature should be 770 ~ 815 ℃, Second, in the calcination process feed speed, tube speed, NH3 traffic and others factors affect the production of tungsten purple in varying degrees. In the preparation of tungsten purple we should to coordinate various relationships in order to produce a single phase purple tungsten. Its chemical equations are: 3 [5 (NH4) 2O · 12WO3 · 5H2O] = 2w18O49 + 40H2O + 35H2 + 15N2. Comprehensive variety of experimental results can be obtained tungsten production violet optimum parameters are as follows:

Temperature/℃
Delivery Rate/(kg.min-1)
Furnace tube rotational speed(r.min-1
NHRate of Flow/(m3.h-1)
790~850℃
0.55
2.0
0.7


                 

2015年11月10日星期二

Blue Tungsten Oxide Producing Tungsten Oxide Process Requirement

When blue tungsten oxide has same quality, the reduction process plays an important role at tungsten powder particle size. In producing fine tungsten powder must be strictly controlled reduction of temperature, hydrogen flow rate, hydrogen gas humidity, the thickness of the material layer, through hydrogen speed and direction, as they will influence fine tungsten powder producing.

Firstly, hydrogen-way requirements, generally speaking, there are two ways through hydrogen: cis hydrogen and inverse hydrogen. When the hydrogen reduction reaction at low temperatures and low humidity conditions, following hydrogen flow direction to push the boat along will obtain fine tungsten powder which is better than using inverse hydrogen way produce tungsten powder.

For another requirement is the reduction temperature, the higher reducing temperature the faster response, the more intense vapor transport, resulting in crystalline powder. And tungsten powder will agglomerate and coarse. Therefore, during the reaction the temperature should use low starting point, warmed gently heating system. Because the reduction temperature is low, heating will not so fast, so the water for the reaction is not too much which is in favor of the producing fine tungsten powder.


Blue Tungsten Oxide Producing Tungsten Oxide Quality Requirement

The quality of blue tungsten oxide has some effect on producing fine tungsten powder, so in order to make more good quality and performance fine tungsten powder, choosing good quality blue tungsten oxide will be the important section.
Firstly, quality blue tungsten oxide are very strict at blue tungsten oxide impurity content, alkali metal, for example, impurities usually is oxygen carriers, and that will delay the oxygen residence time in the powder layer, enhanced chemical vapor migration process, thereby enhancing the tungsten powder particle size.

Secondary, the requirement of blue tungsten oxide particle size, different blue tungsten oxide  particle size at temperature of 800 ℃ through hydrogen the blue tungsten oxide particle size is no the same. The study found that coarse blue tungsten conducive to the production of fine tungsten powder, because coarse particles have good ventilation during reduction and it will help to rule out reducing water vapor.

Finally, the requirements of blue tungsten oxide volatiles, blue tungsten containing different amounts of residual volatiles NH4 and H2O, these volatiles will produce water which will make hydrogen more humidity when blue tungsten oxide reducing tungsten powder. And this is not good for producing fine tungsten powder.


2015年11月6日星期五

Blue Tungsten Oxide To Γ-Tungsten Oxide‘s Reduction Reaction Process

Learn blue tungsten oxide (blue tungsten) phase component is good for producing good performance tungsten powder preparation, according to investigate the phase composition, selecting the raw materials and control of the production process can be more clear which can be producing good performance tungsten powder. Blue tungsten oxide during the restore reaction the main phase component of it is mainly β- tungsten oxide (WO2.9), γ- tungsten oxide (WO2.72), tungsten dioxide (WO2) and tungsten powder.

First discussing the reduction process there are from blue tungsten oxide to γ- tungsten oxide. According to research data shows that the main phase components of β- tungsten oxide are rough and surface has cracks. As the development of reaction the oxygen atoms decrease and vacancy increase, the β-tungsten oxide restore to γ- tungsten oxide. And γ-tungsten oxide surface roughness is further increased, further increases cracks, particle morphology is needle-like and short rod, its irregular, but these structures favor the reduction reaction. γ- tungsten oxide particle morphology depends on reduction temperature, heating rate, material thickness and other factors.


Calcine Temperature Influence Blue Tungsten Oxide Particle Size

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.


2015年10月19日星期一

The Important of Blue Tungsten Oxide Hydrogen Reduction Process

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.



The Current Situation of Doping Blue Tungsten Oxide Producing Tungsten Wire

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.



2015年10月9日星期五

Blue Tungsten Oxide And Purple Tungsten Oxide


At present, the production of ultra-fine tungsten powder, use purple tungsten and tungsten blue two kinds of raw materials exist simultaneously, and therefore these two materials were compared, hydrogen reduction experiments under the same conditions, compare the restored tungsten powder particle size and uniformity of the difference to determine exactly what kind of material is more suitable for the production of ultra-fine tungsten powder. From the microscopic structure and the reduction mechanism of both raw materials analyzed two kinds of raw materials caused by the tungsten powder particle size reduction of hydrogen production and uniformity of the reasons for the differences.


Tungsten oxide reduction process, the particle size will usually change. Currently, the main theoretical explanation W powder particle size reduction process variations have two:
1) growth mechanism of chemical vapor migration. Tungsten and their oxides in contact with steam, will generate a volatile hydrated tungsten oxide (WO2 (OH) 2), evaporated to a homogeneous gas phase reduction reaction occurs with the H2, the reduction product of metal tungsten has been deposited on the nucleation of on the grain, so that the tungsten powder particles grow. This process is the reaction rate, the reduction product forms and materials will change significantly compared.
2) solid-phase local chemical reaction. Solid tungsten oxide contact occurs with H2 gas - solid reaction of oxygen atoms with the gradual removal of lattice rearrangement. This process is slow reaction rate and the reduction product form does not changed.


2015年10月8日星期四

Ammonium Paratungstate Preparing Blue Tungsten Oxide Affecting Factors

Ammonium paratungstate preparing blue tungsten oxide affecting factors are listed as below:
1.Temperature. As the temperature going up, grain size of blue tungsten oxide changes a little and irregularly. It turns out the effect of temperature is not obvious. Oxide content and ammonia content fall down.

2.Feeding speed. Feeding speed mainly controls the reduction time. The faster the feeding speed is, the shorter the reduction time. As the prolong of reduction time, oxide and ammonia content reduces. But the temperature has larger influence than reduction time. Ammonium paratungstate cracks into crystal water and ammonia under high temperature and turns into yellow tungsten oxide. Yellow tungsten oxide which is under hydrogen reduction and turns into blue tungsten oxide.

3.Speed of rotary furnace. As the speed of rotary furnace goes up, blue tungsten oxide grain size will be more even. It is because material gets more contact with furnace and the heating surface is bigger. It increase the uniformity and distribution of grain size of blue tungsten oxide.


2015年9月28日星期一

The Influence Factors of Producing Blue Tungsten Oxide (2)

After studies showed a major factors influence blue tungsten oxide (BTO) performance was particle size and production process. The process production conditions including baking temperature, hydrogen flow and baking time. On one hand, under the certain baking temperature, the particle will grow up and the crack will more rough when hydrogen flow decease. 

But on the other hand when hydrogen flow increase, the particle will finer and uniform. This is mainly because of increased pressure and permeation of hydrogen will change the internal stress of particle, such stress can lead to lattice distortion, resulting in cracking particles. Therefore, the particles tend to rupture and produce a fine particle powder. Baking time also is an important factor for producing fine blue tungsten oxide. The long baking time, the bigger particle and surface crack of blue tungsten oxide. The experiments show, baking solution temperature at 400 ~ 500 ℃, baking time for 30 to 40 minutes, the hydrogen flow 1.51ml / min, will obtain more crack and uniform fine blue tungsten oxide particle.




The Influence Factors of Producing Blue Tungsten Oxide (1)

With the development of science and technology, there are more stringent on quality requirements of blue tungsten oxide. The particle size and morphology of blue tungsten oxide are an important factor affecting the performance of it. After studies show that the raw materials and producing process are important factors affecting blue tungsten oxide particle size.

Firstly, the raw materials, if it has small particle size then using small raw material to produce blue tungsten oxide the particle of it will finer. Besides the blue tungsten oxide particle will more uniform.Secondly is producing process. The main factors which influence particle size is baking temperature, hydrogen flow and baking time and so on. Effect of baking temperature is at the beginning the crack will increase with the baking temperature increase, besides the rule crystal turn to irregularity small particle. But when the reaction reach to a certain degree the blue tungsten oxide particle crack will decrease with the temperature increase. While baking temperature at 400 ℃ blue tungsten oxide particles is uniformly but with the temperature rises, the uniformity of the particles is decline and the particles have grown.





2015年9月23日星期三

Blue Tungsten Oxide Cyclic Oxidation Producing Tungsten Powder

Fine tungsten powder is an important raw material for producing tungsten carbide powder, to improve the performance of carbide tungsten is necessary to reduce or eliminate the coarse tungsten powder particles. Otherwise it will cause tungsten carbide cracks, fracture and other phenomena in the course. After studies the process of using blue tungsten oxide as raw material to produce fine tungsten powder research found that by using exceptionally pure ammonium paratungstate calcinate in ammonia to get blue tungsten and then go through the cyclic oxidation producing fine tungsten powder, and the tungsten powder properties is better which is less coarse. Producing process as follows:

1. Slow heating exceptionally pure ammonium paratungstate which is in ammonia to 600 ℃, when the temperature reach 600℃for 10min heat preservation to produce  blue tungsten oxide.
2. To obtain tungsten powder by restoring blue tungsten oxide in hydrogen.
3. The obtained tungsten powder slowly heating in air to 500 ℃, for the first time oxidation. When the temperature reaches 500 ℃ for 10min heating preservation to obtain tungsten trioxide.
4. The obtained tungsten trioxide in the hydrogen condition to process second reduction.



Blue Tungsten Oxide’s Oxygen Index and Colors

Oxygen index have certain impact on the performance and morphology of blue tungsten oxide, researcher determination of oxygen index of blue tungsten oxide by weight method. After experimental data analysis found that the baking temperature has great impact on oxygen content and the color of blue tungsten oxide. When baking temperature at 350 ~ 500 ℃, the oxygen index between 2.96-2.90. Changing the baking temperature, the color and oxygen content of blue tungsten oxide also will change and surface gloss index has varying degrees of change.

At 350 ℃, blue tungsten oxide’s color is yellow-blue and has high oxygen index, matte. As the temperature increases, blue tungsten oxide gradually be reduced, when the baking temperature reaches at 450 ℃blue tungsten oxide’s color translated into blue-black and surface of it has metal light, oxygen index of 2.94. When baking temperature reached 500 ℃, oxygen index of 2.90, blue tungsten oxide color is blue-black. As the temperature continues to rise in parts of blue tungsten oxide restore into WO2.72 , then the blue color of blue tungsten oxide become more deepen and oxygen index further reducing. When baking temperature reaches 550 ℃, it began to appear purple WO2.72, but most retain the blue color which to form a heterogeneous mixture.





2015年8月24日星期一

Violet Tungsten Oxide Cycle Reduction to Produce Micro Tungsten Powder

Fine and uniformity tungsten powder are key point for producing carbide, and micron and submicron tungsten carbide powder is useful to producing carbide. According to the relevant academic report found that single tungsten oxide can produce submicron or micron tungsten powder. Using violet tungsten oxide (VTO) producing fine tungsten oxide not only the process of it is simple as well as process parameters are easy to control and also equipment are not complex etc. Producing process as follows:

1. VTO were first reduction in hydrogen, along a first temperature of 640 ℃, the second temperature of 760 ℃, third temperature of 860 ℃, when the temperature reaches 860 ℃ heat preservation for 20min.
2. in the air at 500 ℃ making tungsten powder to oxidation with slowly heated for the first time, then heat preservation for 10min.
3. Replace the first step and second to continuous cycle reduction reaction.
4. Using alcohol on the analytical results above steps were dispersed pattern, then using BT-9600 laser particle size analyzer and JXA-840A electron probe scanner to analysis particle size and morphology of samples.

2015年8月12日星期三

Tungsten Oxide Materials Application

Tungsten oxide has good physical and chemical properties, so it can be widely applied in many different fields. Its ultra-fine powder has a strong absorptive capacity of the electromagnetic wave, so it can apply in solar energy field which can be an absorbing material, and in the military field it is an important stealth material. And tungsten oxide has a special catalytic properties in the fuel cell can be used as the anode electrode catalytic materials, as well as can be low-temperature superconducting materials, but also often doped with TiO2 as a photocatalyst and so on. Tungsten oxide film based on tungsten oxide powder material having a broader application, it can transform it presents color when giving appropriate optical radiation or using electric field. And this is photochromic or electrochromic. And at present these technologies are widely used in electrochromic windows, large information displays, and automotive mirrors and so on. Meanwhile tungsten oxide for NOX, H2S, NH and other gases are highly sensitive, so as a sensitive material of the sensor can be used for detection of food, medicines, and other exhaust. Tungsten oxide active apply in different fields, so the study of the tungsten oxide still continue to carry out, and it has also become one of the most potential for development of materials.

tungsten oxide


2015年8月10日星期一

Purple Tungsten Oxide Production Manufacture Process

Purple tungsten oxide using the APT as raw materials,which is during at the closed furnace in the industry. Under certain conditions, adding NH3 during calcination, and the NH3 will decompose H2 and N2, it will form a wet hydrogen atmosphere furnace in the stove, so that APT under mild reducing atmosphere, gradually decompose, generating purple oxide reduction. There are many factors in the process of preparing purple tungsten, one by the hydrogen reduction of tungsten oxide mechanisms apparent hydrogen greater humidity, the temperature required to obtain the higher tungsten purple, so choose the calcination temperature should be 770 ~ 815 ℃, Second, in the calcination process feed speed, tube speed, NH3 traffic and others factors affect the production of tungsten purple in varying degrees. In the preparation of tungsten purple we should to coordinate various relationships in order to produce a single phase purple tungsten. Its chemical equations are: 3 [5 (NH4) 2O · 12WO3 · 5H2O] = 2w18O49 + 40H2O + 35H2 + 15N2. Comprehensive variety of experimental results can be obtained tungsten production purple optimum parameters are as follows:

Temperature/℃
Delivery Rate/(kg.min-1)
Furnace tube rotational speed(r.min-1
NHRate of Flow/(m3.h-1)
790~850℃
0.55
2.0
0.7




2015年8月4日星期二

Particle Size and Bulk Specific Gravity of Blue Tungsten Oxide

By using SEM to observer the particle size and bulk specific gravity of blue tungsten oxide discover that baking temperature between 400 ~ 500 ℃ blue tungsten oxide particles more uniformly. When baking temperature at 400 ~ 500 ℃ can obtain fsss particle average of 11.9 ~ 12.0um, bulk specific gravity of blue tungsten oxide 2.49 ~ 2.50 g / cm2. When baking temperature at 400 ℃, blue tungsten oxide average fsss particle size is 12.0um and bulk specific gravity is 2.50g / cm2. when the baking temperature is 450 ℃, the fsss particle size is 11.9um, bulk specific gravity is 2.50 g / cm2
The solution temperature baking at 500 ℃, Fei particle size of 12.0um, bulk specific gravity of 2.49 g / cm2.
Analyzing the above data can be found, baking temperature between 400 ~ 500 ℃ the particle size distribution curve is quite the same and the particle are uniformity. Within each temperature range, the particle size distribution fluctuates within a region, each particle size distribution mainly between 10 ~ 40um and the bulk specific gravity fluctuation is not great. At the same time at different temperatures, the average diameter of blue tungsten oxide particle size also has a corresponding effect. The higher the temperature the blue tungsten particle size will be increased, but the impact is not obvious.

temperature(℃)
400
450
500
Fsss (um)
12.0
11.9
12.0
bulk specific gravity(g/cm2
2.50
2.50
2.49








2015年7月30日星期四

Ammonium Paratungstate Preparing Blue Tungsten Oxide

In 1950s, tungsten powder is often prepared by tungsten acid and yellow tungsten oxide. In 1960-1970s, America, France, Netherlands and Britain used blue tungsten oxide to produce tungsten powder instead of tungsten acid and yellow tungsten oxide. China started to do the research on blue tungsten oxide in 1970-80s. Tungsten powder property is being affected by a lot of factors including producing method and raw material. When producing super fine tungsten powder, the oxide content of tungsten oxide should be low. When producing fine tungsten powder, oxide content of tungsten oxide should be higher. Thus the producing method of blue tungsten oxide which is of low cost, high property and environmental friendly is under investigation.
Use ammonium paratungstate as raw material, under specific preparing technology and certain temperature, ammonia cracked into hydrogen, ammonium paratungstate is under micro reduction and then blue tungsten oxide is prepared.

Analyzing Blue Tungsten Oxide Appearance


Learning blue tungsten oxide (BTO) phase morphology, size and uniformity, help to improve the performance blue tungsten oxide, so that it can be applied in more areas. To produce blue tungsten oxide is boat loading ammonium paratungstate (APT) to the hot zone and during the process to control the hydrogen flow, temperature and holding time these three parameters to produced blue tungsten oxide.



By using hydrogen reduction method to produce blue tungsten oxide and the surface of it has a large number of cracks and voids star, breakage obviously, it has lost the characteristics of hexagonal grains, forming a loose rule like appearance. Blue tungsten oxide surface has cracks is due to a large amount of water molecules and ammonium molecules which is produced from APT decomposition during the reaction. So the crystal inside of APT will cause inner stress to make crystal lattice mutation, resulting in cracks. At the same time, the external hydrogen to penetrate APT inside promoted deepening and expanding of cracks. Because of this crack APT generating vacancies and in baking time it caused partial intense contractions to make further fragmentation then to produce a fine particle powder.

2015年7月24日星期五

Tungsten Oxide Applications

Tungsten oxide is a kind of tungsten acid anhydride, tungsten acid salts products, including tungsten trioxide and tungsten oxide, and in practical industrial production there is no tungsten oxide product, tungsten oxide is widely used in modern industrial production and processing. Tungsten oxide applications are listed as below:

1.Tungsten oxide is used for many purposes in everyday life. It is often used for industrial X-ray phosphor screen and fireproof fabric manufacturing tungstic acid salt, also used as ceramic and paint in the paint.

2.Tungsten oxide was also used to produce electrochromic window and smart window. The window is automatically switch glass, pervious to light performance and the change of the applied voltage, allows the user to tone their window, through the change of quantity of heat and light.

3.Tungsten oxide is used in the production of chemical products, such as paint and coatings, and catalyst in the oil industry. But oxide is a kind of intermediate products, a large number of tungsten oxide is used for metal tungsten powder and tungsten carbide powder, and then used in the manufacture of metal tungsten products in the production, application and production of tungsten alloy products, and a large number of the tungsten copper, nickel, tungsten, tungsten nickel iron, silver, tungsten rhenium tungsten and tungsten thorium, etc., while the most widely used in the industrial field is tungsten base material in the production of various grades and by way of cemented carbide products.



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2015年7月16日星期四

Blue Tungsten Oxide

Tungsten oxide (W2O3) is a compound of tungsten and oxygen. It has beenreported (2006) as being grown as a thin film by atomic layer deposition at temperatures between 140-240 °C using W2(N(CH3)2)6 as a precursor. It is not referred to in major text books e.g. Some older literature refers to the compound W2O3 but as the atomic weight of tungsten was believed at the time to be 92, i.e approximately half the modern accepted value of 183.84 the compound actually being referred to was WO3.
Blue tungsten oxide is is also called tungsten blue oxide (TBO). It is used primarily for the production of tungsten metal power and tungsten carbide. The formula of blue tungsten is H0.5WO3. Blue tungsten oxide is finely divided blue-violet crystalline powder and it is produced by rotary calcining ammonium paratungstate at closely controlled temperatures in a reducing atmosphere. And we usually use APT to manufacture it by calcination. Blue tungsten oxide paly an important role in the line from oxide to W and WC powder. The color varies between deep dark blue to blue,faint blue and green blue. Also the TBO particles are pseudomorphous to the original APT crystals, as described for tungsten trioxide. It is not a chemically defined compound, but consists of various different constituents, like trioxide, tungsten bronzes and different lower tungsten oxides. The relative amount of these compounds in TBO depends on the calcination parameters.

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