Based on high density, high strength, excellent chemical stability and arc ablation resistance, tungsten copper material also has perfect thermal and electrical conductivity, which can be widely used in EDM electrodes, electrical contacts, military industry and heat sink materials. However, tungsten copper electrodes and contacts used for electrical machining has different requirements of properties with tungsten copper used in heat sink. As heat sink materials, tungsten copper not only be supposed to have excellent thermal conductivity, but also should have excellent hermeticity to ensure the equipment working stability. Since any porosity and leakage will lead to the operation failure of the microwave component.

In the early 1980s, tungsten copper has been chosen as heat sink materials, which due to it has the similar coefficient of thermal expansion to some ceramic, and both of them after brazing can not only guarantee the thermal matching, but also form a good thermal channel. Theoretically, W and Cu has big difference in physical and chemical properties, which the difference of melting point of them are as much as 2000℃. And they can not form a solid solution or a compound so that it is only suitable for using powder metallurgy process. And the best process is infiltration, tungsten powder is compacted to a certain density of blank, after sintering and shrinking at high temperature forms tungsten skeleton with a certain density and then at a temperature above the melting point of copper was infiltrated tungsten skeleton.

Since the high hardness and poor plasticity of tungsten powder, using a general manufacturing method infiltrated tungsten copper alloy will be some of the pores, the relative density can only reach about 60%. Densification at high temperatures also have some closing pores in copper infiltration process is not sufficiently filled with tungsten skeleton, reducing the product's tightness. In order to reduce the porosity of the relevant parameters need to be improved so that it can meet the requirement of hermeticity.

Tungsten carbide additives play an important role in inhibiting the WC grain growth, and there are several major additive inhibitory effects: VC> Cr3C2> NbC> TiC> Mo2C> TiC> ZrC> HfC. Their inhibition principle includes:

1. Growth inhibitor changed the energy and characteristics of the solid / liquid interface, hindering the process of tungsten carbide precipitation and dissolution;

2. According to two-dimensional nucleation theory, the border energy leads to subtle changes in a significant change in the control of grain growth of two-D nucleation. During sintering grain growth inhibitors can be added by increasing the boundary can improve dimensional nucleation energy obstacle, making it the nucleation rate dropped significantly, WC grain coarsening has been suppressed;

3. Grain growth inhibitor can change the interface energy or interfere the surface dissolution- precipitation process; and it has higher solubility and diffusion coefficient in the binder phase Co, mainly through migration or diffusion bonding phase in the WC / Co interface, so it is likely to grow crystal grains in the activation WC lattice deposition occurs, thereby preventing the further growth of grains;

4. Add grain growth inhibitors will reduce the rate of diffusion of the activation energy is increased, and it will migrate along the WC / Co interface segregation occurs thereby restricting grain interface.

As an anti-corrosive component, Cr3C2 can be used as additives to improve the corrosion resistance of cemented carbide. It usually added in an amount to be controlled within the solid solubility of Cr in the γ phase, so it can improve its corrosion resistance without compromising the strength of the alloy. The basic principle is dissolved in Cr and Co binder phase in which surface to form a layer of passive film, can significantly reduce the current density, and the higher the ratio of Cr / Co and blunt alloy is greater. The addition of rare earth elements, such as molybdenum (Mo), niobium (Nb), tantalum (Ta), rhenium (Re), ruthenium (Ru) can significantly improve the high temperature properties of the cemented carbide. Ru can keep Co hexagonal structure stable at high temperature and improve the toughness and wear resistance of tungsten carbide; Re can form solid solution with Co, and Co-Re binder may significantly increase the softening temperature and reduce tackiness during processing.

These metal elements are usually added in the wet milling process, except some added in the form of master alloy. In addition, there are some non-metal can be used as additives, such as P, B and some carbide. It forms low-melting eutectic by reacting with other metals, and WC grain will rapidly dissolute in the liquid at relatively low sintering temperature so the alloy can be densified rapidly; while carbide can be synthesized at high temperature and pressure diamond diffuse carbide, which has a hardness close to diamond as well as close to conventional carbide toughness.

Tungsten carbide (WC-Co) consists of the hard phase WC and the binder Co, it has higher hardness, high strength, high melting point and excellent wear resistance, which can be widely used in cutting tools, molding and drilling industries. However, with the expanding application and more and more complex conditions, tungsten carbide with WC-Co system can not entirely meet the requirements of the working performance. Tungsten carbide additives appear to effectively solve this problem, different additives can be suitable for different properties of tungsten carbide required.

For instance, in order to suppress the grain growth, the grain growth inhibitors can be used (TaC, MoC, VC); in order to improve the density, toughness and other properties, we can add the corresponding rare earth elements; in order to improve the corrosion resistance of tungsten carbide, we can add some ingredients of corrosion resistance. A relatively small amount of additives, will not have a greater impact on the original carbide other properties, but can significantly improve a certain desired properties, which is an ideal solution.

Theoretically, the finer tungsten carbide WC grain size (micron scale to submicron scale, even nanometer scale), its product density, hardness, fracture toughness, impact toughness will be remarkably improved. But correspondingly to prepare tungsten carbide with smaller granularity, its specific surface area larger and surface activity greater and it easily grows during the sintering process, so the grain growth inhibitors plays a important role. There are several major additive inhibitory effects: VC> Cr3C2> NbC> TiC> Mo2C> TiC> ZrC> HfC.

Atomic absorption spectroscopy (AAS) is a spectroanalytical procedure for the quantitative determination of chemical elements using the absorption of optical radiation (light) by free atoms in the gaseous state. Tungsten boat atomic absorption spectrometer is one of the most important types of AAS.

Since the 1990s, with the rapid development of industry in China, toxic element produced by industry harmful, such as leas which can cause a variety of human diseases. The issue that the over-standard rate of blood lead of adolescent is 30-80% gets a great attention in public. Tungsten boat AAS can solve the problems of blood lead testing in clinical testing.

Tungsten boat AAS uses the standard test method, atomic absorption spectrometry. This type of instrument can detect trace amounts, and has a high sensitivity, the accuracy of result is also very high. In addition, tungsten boat AAS has an advantage of a low power and it doesn’t need for any industrial electricity. It doesn’t require for a good installation condition and cooling water and other assistant equipment, so the operation is much simple than other types of AAS. When exterminating, it is convenient for tungsten boat AAS to collect blood samples. Tungsten boat AAS only requires less blood but can obtain concentration data of lead, cadmium at the same time and it only takes about two minutes to obtain the test data.

Compared to the other types of AAS, the operating cost of tungsten boat AAS is much lower. In the detection of concentration of lead and cadmium, each part only requires one diluent. Then print the test results directly with the intelligent computer without manual calculations. On the other hand, the appearance of tungsten boat AAS is more exquisite, it is easy to move. It is suitable for infants, young children, pregnant women, adolescents, the aged, adult health checks, and other special checks.

Since the tungsten boat AAS occurred, through a large number of clinical experiments and experimental observations and professional certification, its excellent performance and simple operation method obtain the praise of experts. They indicate that the tungsten boat AAS is considered as an international leading technology, it solves the problems which are beset for a long time in clinical examination in detecting trace elements. Tungsten boat AAS is the most desirable instrument to replace the graphite furnace AAS to detect blood lead and cadmium.

Tungsten crucible is an important deep-processing product of tungsten. As the main manufacturing techniques of tungsten crucible, isostatic pressing - sintering, forging, chemical vapor deposition, plasma spraying, a spinning and rivet linking and welding process have their own characteristics. Properties of tungsten crucible made by different manufacturing techniques also have some differences. The following is a brief analysis for merits and drawbacks of the six manufacturing techniques of tungsten crucible.

Isostatic pressing - sintering: Most of tungsten crucible are mainly made Isostatic pressing - sintering process. It has a high maturity because of a long history development. The main process of this manufacturing technique is pressing. Quality of the finished tungsten crucible made by isostatic pressing - sintering process is relatively stable. And it can produce large-size products. But it is easy to crack the bottom of tungsten crucible because the improper operation in the pressing process.

Forging: Forging is a key step of manufacturing techniques. The density of tungsten crucible made by this process is relatively high, therefore, anti-deformation and higher-temperature deformation resistance of such tungsten crucible are better than other types of tungsten crucible. However, forging process is finished by the processing of tungsten rod, so it has a lower utilization of materials. And the diameter of products made by forging is much small.

Chemical deposition process (CDV): With the continuous research and development of chemical deposition process in recent years, the maturity of it becomes much higher. The density of tungsten crucible made by this process is high, and it can produce the large size tungsten crucible with a thin wall. However, because of the short developed time, the maturity of the technology is not enough.

Plasma spraying forming: This process is capable of producing large size tungsten crucible. However, due to the size of the tungsten powder, internal organization of finished tungsten crucible is not tight enough, which will produce more pores, and result in density of tungsten crucible cannot reach a high standard.

Spinning: This process can produce high-density products. However, due to complexity of hot rolling process and the spinning process, it is difficult to operate.

Rivet linking and welding: Rivet linking and welding is capable of producing large size tungsten crucible products with thin wall. However, the metal welding process is the key step of rivet linking and strength of the metal junction is low.

Different manufacturing techniques have different advantages and disadvantages, the users should choose a different preparation process in according with the requirements of the finished tungsten crucible improve the quality and the rate of the finished products. 

Tungsten boat is also known as evaporated tungsten boat or coated tungsten boat. It is formed by tungsten sheet through high-pressure tungsten. Nowadays, tungsten boat is widely used in vacuum coating industry and sintering furnace and annealing boat industry. There are many specifications of tungsten boat and their shapes are different.

Tungsten's unique properties, including a melting point of 3410° C, low vapor pressure at elevated temperatures and low coefficient of thermal expansion, make it of value in a variety of high temperature products and processes. First of all, the boat type component is made of tungsten metal. And then connect both ends of the component by wire, and put a low melting point metal in the middle of the concave position. Under the electrify condition, the temperature of tungsten boat would rise to about 2000 degrees, so that the metal can evaporate into gas and deposited on the surface of the workpiece.

Tungsten boat is also widely used as source for evaporation resistance. Its working methods is to make tungsten film into the shape of the boat firstly, then install it in two electrodes. Add materials in the center of tungsten boat, and then energize the electrodes slowly. After the current pass tungsten boat, the tungsten boat will give out the heating power. Low voltage and high current would transfer the heating power to the coating material, when quantity of heat of tungsten boat is higher than the melting point of the coating material, the material would obtain the sublimation or evaporate. But tungsten boat still has some limitations for vacuum coating. The film evaporated by tungsten boat has a low density, and there are a lot of materials cannot be deposited in this way. When tungsten boat evaporating and coating materials, the melting point of the material cannot higher than the melting point of tungsten boat.

Tungsten boat is also widely used in electronics industry, such as kinescope, mirror making, toys, household appliances, mobile phones, electrical enclosure. It has good characteristics for electrical conductivity, thermal conductivity, high temperature resistance, wear resistance, corrosion resistance. In addition, tungsten boat has a high melting point, low saturated vapor pressure and stable chemical properties, so it has been widely used as source for resistive evaporation in vacuum evaporation coating industry. Tungsten boat, as an essential part for vacuum coating equipment, the selection of tungsten boat determines the quality of the coating.