The advantages of Gamma tungsten shielding material:
It's density is very high, the reduction in the physical dimensions of the shield assembly does not affect the validity of their rigid or shielding characteristics. Compared with traditional radiation shielding materials, gamma tungsten shielding material provides excellent value.


The high-density tungsten alloy can provide the same energy absorption of lead use 1/3 less material! Unlike lead, you can also reduce the cost of management,  it is not necessary to have a sepical permission. Tungsten alloy radiation shielding material can be widely used by reliable customers around the world.

 

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Tungsten: tungsten and various metal alloys and tungsten compounds are often used in various forms of radiation shielders. Its high density meets the  main requirements of shielding material, and is used for the shielders.The high atomic number of the tungsten is also very important. 


The tungsten can be easily processed, it is the added value.the shielding container of radioactive material is usually made ​​of metal tungsten. Radioactive material  usually by remote control in laboratories and hospitals,  it is usually installed  in the safest position of the room lined plate tungsten bricks and X-ray machine.

 

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Nano tungsten powder is fine particles of tungsten powder to the nano-level powder. The preparation of nano tungsten powder uses the nanotechnology.

What is the nanotechnology? Nanotechnology actually is the technology for a single atomic, molecular manufacturing.

There are three concepts about nanotechnology: The first is an American scientist Dr. Drexler pointed out the molecular nanotechnology in 1986. Under this concept, the combination molecules machines for practical use, and thus can combine all kinds of molecules,  and can turn out any kind of the molecular structure. This concept of nanotechnology does not make ​​significant progresses.

The second concept of nanotechnology is positioned as the limit of the micro-machining technology. That is, the "processing" of nanometer precision to manually form the structure of the technical of the nano-size. Even if the existing technology continues developing, it will eventually reach the limit. This is because, if the line width of the circuit is smaller, the enable circuit is constituted of an insulating film is extremely thin, so that  can destruct the insulation effect. In addition, there are issues such as fever and shaking. In order to solve these problems, researchers are studying a new type of nanotechnology.

A third concept is from the biological point of view. Originally, there nanoscale structure in biological cells and biofilms.
 

The nanotechnology, is to study the law of motion of electrons, atoms and molecules and characteristics of a new technology in a scale of 0.1 to 100 nm. Scientists find dozens of the number of atoms or molecules in the process of studying the material constitutions. Taking advantage of these features of manufacturing technology to make specific function devices ,this technology is known as nanotechnology.

 

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The hardness of cemented carbide is high  (86 ~ 93HRA, equivalent to 69 ~ 81HRC).And it has the advantages of  hot hardness and good wearing resistance,which the hot hardness isup to 900 to 1000 ℃, keep 60HRC.

The cutting speed of cemented carbide  tool is 4 to 7 times higher than high-speed steel and the life of  tool is 5 to 80 times higher than high-speed steel.


But the frangibility of  cemented carbide  is good, it can not be cutted and processed. It is difficult to form the complex shapes of the tools.As a result, it is often used in the production of different shapes of the blades.It can use these methods such as welding, bonding, mechanical clamping to mount on the blade bodies and the molds.

 

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The selection of carbide grade on the cemented carbide blade material is based on different addresses and different functions of the cemented carbide blade.

Cemented carbide blades have the characteristics of  high precision and high wear resistance and  has been widely used. According to the different uses of the product, cemented carbide blades can be divided into the wood cutting tools, clamping blade, milling and turning blades.

Cemented carbide  is made by the chemical vapor deposition (CVD) method,which coats TiC or TiN, HfN, Al2O3, and other wear-resistant on the surface of the carbide alloy inserts,so that the carbide alloy coating is formed. This is an important progress of modern cemented carbide  researches. The Sidek Krupp and the Swedish Sandvik company had developed TiC coated carbide inserts and put it into the market for the first time in 1969. After 1970, the United States, Japan and other countries were beginning to produce this  kind of blade. For more than thirty years, the coating technology has made great progress. Coated carbide blade has been developed from the first generation, the second generation to the third generation, fourth generation products.

                  
The advantages of cemented carbide coating:
1) coated cemented carbide  can  use the high cutting speed, thereby improving the processing efficiency;

2) since the smaller coefficient of friction between the coating material and the  processing material ,compared with uncoated blades, the cutting force of the coating blade has a certain decrease;

3) when the processing of the coating blade, the quality of processed surface  is excellent;

4) due to the good overall performance, coated blades have good versatilities. One coating grades of the blade can be widely used.

 

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The most important part of a dart is the stem, it’s where fingers hold on. The change of stems’ weight will change the shape of darts. Nowadays standard dart stem is made from tungsten alloy and this kind of dart is getting more and more popular all over the world.

There are several kinds of tungsten alloy dart stems including tungsten-nickel-copper stem, tungsten-nickel-copper-iron stem etc. If customers need special darts, they will be customized. Since there are still some barriers in manufacturing skills, tungsten dart stems with purity of 100% can not be made yet. What people can buy in the market are almost tungsten alloy stem, among which tungsten-nickel-iron alloy is the most common one.

Tungsten is a kind of material with high density and endurance. Tungsten alloy dart has small diameter compared with dart made of other materials at the same weight. For dart fans, small-size stem is very important, for it’s more comfortable to hold with fingers. The advent of tungsten alloy darts has contributed a lot to dart sports, as it has greatly improve the average scores in games.

There are some tips for dart fans:

1. When you buy a new set of darts you may notice the percentage of tungsten in the package, say, “tungsten purity 80%”, that means 80% of the material in the stem is tungsten, and the higher the purity the thinner the stem is and, of course, the more expensive the darts are. For ordinary fans 80% is good enough.

2. Remember: the only advantage of a high-purity tungsten alloy dart is that it is thinner, it does not mean it’s of high quality or fine workmanship.

3. Some people are allergic to nickel, and nickel happens to be an element of some darts stem, if those people really want to play dart, they’d better chose a substitute, like tungsten -copper darts.

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The key characteristics of CVD tungsten carbide coatings are as follows:

1、Outstanding chemical and corrosion resistance
2、Free from through porosity, thus effectively protecting mild steel substrate from corrosive media without sealing the coating
3、Superior resistance to sulfide stress cracking
4、Provides effective protection against mineral acids such as sulfuric acid and hydrochloric acid
5、Resists Aqua Regia at room temperature
6、Superior wear resistance; Wear rate of CVD tungsten carbide coatings is four fold lower when compared to thermal spray WC, 12 fold lower than hard chrome, and 40 fold lower when compared to abrasion resistant steel AR-500
7、Demonstrates better erosion rate when compared to chrome carbide weld overlay, hard chrome, white iron, cemented carbide, and various other hard materials
8、Better fatigue resistance and toughness
9、Superior resistance to impact and deformations
10、Deposition from the gas phase enables coating of internal surfaces and intricate shapes.

A micro-photograph of a cross-section of 50-microns thick CVD Tungsten Carbide coating type T on thread. The uniform coating follows the substrate; even slight imperfections are accurately followed (magnify. 20X).

Comparison results of ASTM G65 tests of CVD tungsten carbide coating abrasion resistance against other hard materials is depicted.

Results of ASTM G65 tests of CVD Tungsten Carbide coating abrasion resistance as compared to the results for other hard materials.

Corrosion resistance of CVD tungsten carbide coatings is demonstrated.

Samples of three different coatings after salt spray corrosion tests: left - HVOF after 480 hours; centre – Hard Chrome after 288 hours; right – CVD coating type T after 480 hours.
Applications of CVD Tungsten Carbide Coatings

CVD tungsten carbide coating is suitable for applications with many different components operating in extreme erosive and abrasive atmospheres, such as critical components of metal seated ball valves, downhole tools, and pumps handling abrasive fluids.

Ball valves coated with CVD tungsten carbide coating, demonstrate increased valve life thanks to the coating as it make them scratch-proof and able to resist erosion and abrasion.

Ball valves coated with CVD Tungsten Carbide coating.

CVD tungsten carbide coating extends the life and reduces downtime costs of downhole tools such as grippers for down-hole tractors, high loading bearings pins, and mud-driven hydraulic parts for directional drilling tools.

CVD tungsten carbide coating type T is applied on outside piston and inside cylinder of a positive displacement pump transporting abrasive viscous fluids at pressures as high as 2800 psi to reduce wear, thus increasing pump life threefold.

CVD tungsten carbide coating is an ideal alternative to phase-out hard chrome plating because it involves carcinogenic hexavalent chromium, thus causing negative impact on environment, health and safety.
Conclusion

With these qualities, CVD tungsten carbide coating becomes an ideal solution to improve the performance and life of critical components of valves, downhole tools, and pumps operating in power generation, cryogenic equipment, refineries, food manufacturing, and oil and gas facilities.
About Hardide Coatings

Hardide Coatings produce a range of advanced surface engineering coatings that protect the internal and external surfaces of components from wear, erosion and acidic corrosion.

The coatings are proven to extend the life of metal parts operating in harsh environments for a variety of industries including oil & gas, valves, pumps, aerospace and advanced engineering.

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The life of critical components and tools can be increased by many different hard coatings and surface treatments such as boronizing, nitriding, hard chrome plating, plasma and thermal spray coatings, physical vapor deposition (PVD) and chemical vapor deposition (CVD) coatings. However, each technique has its own disadvantages. This article discusses the innovative CVD tungsten carbide/tungsten coating named as Hardide, Which exhibits exotic properties.
Types of CVD Tungsten Carbide/Tungsten Coatings

CVD tungsten carbide coatings are different from other tungsten carbide coatings as they do not use cobalt or nickel metal matrix binder. CVD tungsten carbide/tungsten Coatings are available in four different types.

The hardest coating type H comprises pure tungsten carbides, thus demonstrating high hardness but with only 'satisfactory' toughness. The multi-layer coating type M features layers of different hardness. It is possible to modify the overall coating characteristics by changing the ratio between the thickness and properties of individual layer based on specific application requirements. CVD tungsten carbide coating type T is the most widely used coating.
Nano-Structure of CVD Tungsten Carbide Coating Type T

Coating type T is a sophisticated nano-structured material comprising a metallic tungsten matrix with dispersed tungsten carbide nano-particles with a typical size range of 1-10 nm.

High resolution electron microscopy image of precipitate in CVD coating type T deposited on Cu substrate. The atomic distances (1.49 and 1.76 Å) directly taken from the precipitate region are matched best to the lattice constants of W2C (110- 1.49 Å and 102 - 1.74 Å).

The coating type T demonstrates abrasion resistance up to twelevefold higher than that of hard chrome and improved hardness of more than 1100 Hv. The coating can be formed on titanium, low alloy and some tool steels, stainless steel, and Ni-, Co- and Cu-based alloys. This nano-structured material shown unprecedented impact resistance, crack resistance and toughness by tolerating 3000 microstrain deformations without any deterioration.
CVD Tungsten Carbide Coating Porosity

CVD tungsten carbide coating is devoid of through porosity from a thickness of below 1 µm thanks to its deposition mechanism. The crystallization of the coating takes place from the gas-phase atom-by-atom, and the defects and micro-pores in the coating are filled by the highly mobile reaction products as the coating grows.

SEM image of a cross-section of CVD coating layer on cemented carbide substrate. The coating as deposited has exceptionally low porosity and it can isolate substrate material against attacks of aggressive media, such as acids.

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Tungsten carbide is a main raw material in the making of tungsten carbide alloy, it is also know as Wolfram Carbide. Tungsten carbide has metal gloss and has hardness similar to adamas, it is also a good conductor of electric current, its melting point is 2870℃ and boiling point 6000℃，relative density is 15.63 （at18℃）. This kind of material does not dissolve in water, hydrochloric acid and vitriol.

Owing to these physical properties, tungsten can be used in making, attrition-resisting, strike-resisting and corrosion-resisting moulds, the use of tungsten in moulds can extent the their service lives. Thus will effectively save the cost of moulds in production and improve economic performance. This sort of mould can be used in our special processing, too. It is known that China is the largest manufacturing country in the world, the application of mould is wide in many areas. Tungsten carbide moulds will undoubtedly receive warm welcome from a great number of enterprises. Experts therefore expect that tungsten carbide moulds will have board prospects in the market. 

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