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 Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn
 

Experimental material: high-purity hydrogen, high purity argon gas and high-purity tungsten hexafluoride and deposition matrix: copper tube.

Experimental procedure:

Decontaminating, acetone washing and drying the surface of deposition matrix, which would be placed in the reaction chamber then.

To avoid the explosion due to hydrogen mixed with air, argon should be purged into the reaction chamber and all the pipelines to empty the air. After emptying air, open the hydrogen flow needle valve, pass over the hydrogen and then light the exhaust gas discharged, then close the valve;

Heating the deposition matrix by current to make it achieve the required deposition temperature;

After mixing the WF₆ and H₂ according to a certain proportion, passing them through the reaction chamber through the flow control device;

WF₆ and H₂ react chemically on the surface of deposition matrix, to obtain deposition layer of refractory metal;

After a certain reaction time, turn off the heating power and reactive gas control valve, so the reaction chamber will be cooling;

Removing the sample after the temperature drop to below 100 ℃, and obtaining tungsten tube by means of cutting, and the removal of the deposition matrix.

By changing the deposition temperature and gas flow rate to get tungsten tube in different processes, and then test its properties.

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Experimental materials and reagents are as follows:

H₂: High Purity(99.999％),it is reduction gas;

WF₆: High Purity(99.9％),it is reactant gas;

Ar: High purity(99.999％), it is used in the reaction system for evacuating air;

Deposition Substrate: copper (there are different diameters: 6mm, 10mm, 16mm, and 35mm);

Tungsten tube is processed by CVD (Chemical Vapor Deposition) method.

Under the following conditions: the deposition temperature is the same (600 ℃), and the deposition matrix diameters (6mm, 10mm, 16mm, 35mm) is different. The morphology of tungsten tube obtained by the aforementioned condition is fine columnar crystals and its growth direction is almost identical to brass radial.

By comparing the microscopic morphology of tungsten tube obtained under the above conditions, what is found that the parameters of tungsten tube in the subsequent depositing process can be ignored, that is to say, you can ignore the impact of the deposition matrix diameter on tungsten tube matrix microstructure morphology.


Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Under different deposition temperature (500 ℃, 600 ℃, 700 ℃ and 800 ℃), keeping the composition proportion and the inlet content of WF₆ and H₂ the same amount, the cross section metallographic microstructure of the tungsten tube processed by CVD (Chemical Vapor Deposition) is different.

When the deposition temperature is lower(500 ℃), the organization of the deposited layer presenting fine crystalline column;

When the deposition temperature reach 600 ℃, the speed of the tungsten atoms generated by the chemical reaction of the reduction will accelerate. In the deposition process, some grain grow ing occasionally get the lateral growth space and grow, which will make deposit layer of column grain structure coarsening.

Some occasional rapid growth of the grain growth to obtain the lateral growth space and growth

When the deposition temperature is raised to 700 ℃, the speed of the tungsten atoms generated by the chemical reaction of reduction has been very fast, these tungsten atoms deposited on surface of deposition will restart growth interface nucleation and further growth. In this process, morphology of the deposited layer will change significantly. Re-nucleation process will result in, firstly, columnar crystal growth pattern of the deposition layer will tend to clutter; secondly, the crystal grain of deposition layer will obviously refined.

If the deposition temperature rising to 800 ℃, re-nucleation process will be more obvious, at the same time, the microstructure of the deposited layer has lost columnar crystal growth characteristics, and its organizational form is messy and grain size is uneven.


Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

As the CVD (Chemical Vapor Deposition) process, by constantly absorbing tungsten atom, initially formed thin polycrystalline grain, which will grow in all directions and form the randomly oriented growth area of deposition microstructure.

After a further depositing and growing, since the cross growth of these crystal grains in all directions will stop growing due to the mutual contacting and blocking among crystal grains, so only the growth in a direction which is perpendicular to the surface of copper matrix is able to obtain required crystal grains growth space, in order to continue to grow. Because there is such a competitive growth way, so a columnar grain structure is ultimately formed, whose direction is perpendicular to the growth development of the surface, whereby the region is mainly composed of deposition layer.


Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

CVD tungsten tube morphology:

In the CVD (Chemical Vapor Deposition) process, due to the chemical reaction with H₂, WF₆ adsorbed on the surface of the copper matrix reduce to tungsten atom, and these tungsten atoms will gather nucleation on the copper matrix surface and grow, at last, the tungsten tube is formed by cutting and other process.

The formation of the first layer of the microstructure is related to the forming process of the initial crustal nucleus of tungsten layer and nuclei initial growing up process.

Tungsten atoms will deposit and diffuse on the surface of the deposition matrix and gather on the surface of the active matrix position, these positions are usually near the grain boundary, surface level position and the crystal defect surface outcrops.

When nucleation aggregated reach a certain degree of supersaturation, the deposited layer of crystals will form initial nuclei. Because those active sites presented on the deposit surface distribution is not uniform, so, from the microscopic point of view, the initial deposition surface nuclei are not uniformly distributed.


Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Due to its high density, excellent absorption behaviour against radiation, and environmental friendly characteristic, tungsten alloy can be the best choice to produce container inspection tungsten radiation shield. Container inspection tungsten radiation shield is usually used in container inspection system as the main components of gamma radiation detectors, gamma radiation detectors, and neutron radiation detectors. Those detectors can be used in ports, prisons, and border, which can detect weather mass destruction weapons, explosives, weapons, drugs and undeclared goods are hiding in the vehicles.

The photograph below shows the tungsten alloy radiation shielding in container inspection.

  Tungsten Alloy Manufacturer & Supplier: Chinatungsten Online- http://www.tungsten-alloy.com
  Tel.: 86 592 5129696; Fax: 86 592 5129797
  Email:  sales@chinatungsten.com
  Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
  Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
  Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Tungsten carbide buttons are widely applied in geological prospecting, coal mining and oil well boring. Because of its high wear resistance, high bending strength and high hardness, tungsten carbide button is ideally suited for wear parts, other machine parts and dies which are subject to severe service conditions, such as high temperatures, corrosion and abrasion.
Proper usage of tungsten carbide button can avoid button cracking and bending, save physical labor and working time, promote work efficiency.

Figure out the essence of rock drilling is very important. Through study the density and hardness of rock, use the proper grade of tungsten carbide button. Thus avoid the improper use of tungsten carbide button which may cause severe damage due to the over-high pressure. During the drill process, observe the drilling pressure, use the correct drilling method, and stop using tungsten carbide button if it gets blunt. 


Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email:   sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

During the rock drilling process, tungsten carbide button works by impact crushing on hard rock in order to drill holes on the rock. As a result tungsten carbide button will have friction and crash with the rock. It will cause unavoidable abrasion. Before it cracks, abrasion is a normal failure mode of tungsten carbide button.

Tungsten carbide button bit fails because of abrasion which can not drill rock any more. During the crashing and friction, hard grain in the rock penetrates into the soft binder layer of tungsten carbide button. In the later process, tungsten carbide grain spalls and a small part of tungsten carbide button is worn. Under the continuous pressure of rock drilling machine, tungsten carbide button keeps being abrasive and the contact area between rocks enlarges, tungsten carbide grain spalls little by little. At last tungsten carbide button can no longer be used.


Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email:   sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

As mentioned in the chemical vapor deposition method, the coatings of tungsten carbide insert could increase the plastic deformation resistance, but the tool properties like edge toughness is impaired.

Difficultly from CVD method, the coatings generated by physical vapor deposition are thinner, although the ability of protection against heat and plastic deformation is weak, they offers great edge integrity which in turn yields an desired protection against edge chipping.

Generally, it is quite difficult to simultaneously lever up all tungsten carbide insert properties as there are numerous properties of both the protective coating and tungsten carbide substrate and the combination.


Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email:   sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn