Wolfram has the highest melting point of all metals and is therefore also suitable for very high-temperature applications. It is also characterized by a uniquely low coefficient of thermal expansion and a very high level of dimensional stability. Tungsten rod is a kind of metal rod made of metal tungsten, at high temperatures, as a high melting point and low coefficient of thermal expansion material, so it is now widely used for support line, lead-in wire, printer pin, various electrodes and quartz furnace, filament, high-speed tools, automotive products and other industrial fields. Better wear resistance, higher toughness, better deformation and fracture resistance, results in a long life and good size accuracy. Except formed by metal tungsten powder, wolfram rod can also made through the process of the manufacturing of tungsten bar.

Tungsten bar can be divided into wolfram round bars and square bars, during the processing of swaging for tungsten rod, the obtained finished products would have some differences. When both of them are processing to 8mm in diameter, from the view of the sectional of metallurgical structure, the four corners of tungsten square bar are easy to form recrystallized structure under the conditions of processing temperature. If the follow-up process shall not be treated properly, it will result in the interior tissue of the wolfram rod is uneven, which is the main reason for defects and breaking of the following finished wolfram products. On contrary, after tungsten round bar is being stretched to 8mm in diameter, it still remains uniform tissue density. Nonuniform structure tends to cause internal defects of silk material, if uneven degree is very serious that it cannot be processed any more.

Observe hole distribution of this kind of metal rod after annealing, which can be used the scanning electron microscope, you will see the hole of the recrystallized structure correspond to four edges  are less, almost no orifice tube, but there are more holes in intermediate position of the wolfram rod. However, there are not exist recrystallized structure of the tungsten round bars, so its tissue distribution remains homogeneous state in follow-up processing. Internal tissue density distribution of tungsten bar has a great impact on the preparation of the following processes of tungsten rod and tungsten products. Therefore, the users should choose the right tungsten bars according to their own requirements.

Rare earth tungsten electrode usually uses powder metallurgy to produce. Using this method for rare earth tungsten electrode manufacturing, the powder quality will directly affect the sintering and processing properties of the electrodes. During mixed powder reduction process, the phase will usually go through WO_2.9, WO_2.72, WO₂, W and β-W phase change. β-W in the actual production is difficult to obtain, but in the mixed rare earth tungsten powder reduction process can often find this material. After the first reduction observed XRD pattern can find β-W diffraction peaks. With the rare earth content increases, the peak intensity increases. In the second reduction, there are also appeared in the same law, indicating rare earth is favor to produce β-W. On the other hand, the presence of β-W powder causes second-step reduction reaction is not complete, and therefore during rare-earth doped, the reduction temperature should higher than pure tungsten. It can be seen, doped with rare earth will change tungsten powder reduction way. During tungsten powder reduction will first to form β-W, and then converted into α-W. β-W is the A15-type structure, which has a superconducting nature, it attracted widespread attention. But for the good performance tungsten electrode production to produce stable α-W is the ultimate goal of reduction. And to improve the reduction temperature can obtain α-W which is complete reduction.

Doped with different rare earth components, under the same conditions, the reduction particle size obtained is not the same. Under the same reduction conditions, the rare earth tungsten powder particle size is significantly smaller than pure tungsten powder, because rare earth can help to refine tungsten oxide grain size. In various rare earth oxides, Y₂O₃ has better refinement effect and for tungsten powder particle size refinement is the most obvious. In addition, produce multi rare earth tungsten electrode the higher Y₂O₃ content, tungsten powder refinement is better.

In rare earth tungsten electrode, rare earth mainly added in the form of rare earth nitrate. After subsequent doping, drying, reduction processes, rare earth nitrate has be a series of changes and decomposition reactions. Take lanthanum nitrate (La (NO₃) ₃` • 6H<sub>2</sub>O) as example, under inert gas to (La (NO<sub>3</sub>) <sub>3</sub>` • 6H₂O) will produce H₂O, HNO₃, NO, NO₂, and N₂O₅ and other gases. The reaction process and decomposition of cerium nitrate and yttrium nitrate is similar with lanthanum nitrate, but the reaction temperature is different.

To dry the doped powders, the drying temperature can reach 150 ℃. Then the rare earth nitrate will lose crystal water. During reduction, the reduction temperature is generally 400 ~ 1000 ℃. At such a high temperature rare earth nitrate is completely decomposed to produce rare earth oxides.

Analyze XRD of reduction powder found after first reduction there are not diffraction peak of rare earth and clear diffraction peak is WO₂, β-W (W₃O). Indicating that first reduction temperature is lower and the crystal phase of rare-earth is in the low level. Observing the rare earth tungsten powder after second reduction found the diffraction peak mainly α-W, a small amount of β-W, while there has been a significant unknown diffraction peaks. To press and sinter the powder, and then observe its XRD found that the unknown diffraction peak does not disappear. Analyze by PDF card found the peak is similar to rare earth tungstate strongest peak, so it is indicated that the peaks can be rare earth tungstates (La₂WO_6, Ce₂WO₆, Y₂WO₆ and so on.).

Therefore, in the rare earth tungsten electrode, rare earth existence form mainly is LaWO₃, Ce₂WO₆, Y₂WO₆ and other tungstate. Rare earth tungstate after sintered, its calibration peak and relative intensity did not changed significantly, indicating after reduction and sintering the rare earth existence form has not changed.

Dual-energy X-ray absorptiometry is a medical instrumentation of measuring bone mineral density and obtaining relevant data. Two X-ray beams, with different energy levels, are intended to the patient's bones. When soft tissue absorption is subtracted out, the bone mineral density can be determined from the absorption of each beam by bone. Dual-energy X-ray absorptiometry is the most widely used and most thoroughly studied bone density measurement technology. The test results of dual-energy X-ray absorptiometry is more accurate, and is the gold standard for bone density which WHO adopted. Dual-energy X-ray absorptiometry can be used to determine the absorption and ingestion conditions of the raw materials of bones during the process of growth and development of children, and analyze internal and external factors that may affect the growth of children, for the timely development of targeted nutrition programs and exercise plans, to ensure that the advantages of children in the aspects of bone growth and development.

The X-ray generated by dual-energy X-ray absorptiometry is an electromagnetic wave with short wavelength (shorter than the wavelength of visible light), large energy (tens to hundreds of thousands of times larger than the photon energy of visible light) and has penetrating effect, ionization effect and thermal effect. When the human body is irradiated with X ray, X ray can inhibit, destroy and even kill human cells, lead to varying degrees of changes in the physiology, pathology and biochemical aspects of human body. X-rays can also cause hair loss, skin burns, sight disorders, leukemia and other issues. In addition, X-rays also have an impact on the fetus by causing physical handicaps, fetal malformations, fetal brain dysplasia, as well as increasing the probability of childhood cancer. The tungsten alloy shielding can be used to shield X-ray radiation generated by dual-energy X-ray absorptiometry.

Tungsten alloy shielding for dual-energy X-ray absorptiometry is made of tungsten heavy alloy. Tungsten heavy alloy is a tungsten-based material that adds a small amount of nickel, copper, iron, cobalt, molybdenum, chromium and other metal binders. It has the characteristics of high density, high strength, good absorption capacity of rays and good machining property. Because the greater density of the metal means the better absorption capacity and shielding capability of rays, thus tungsten alloy shielding for dual energy X-ray absorptiometry  has excellent radiation shielding property that can effectively shield the X-ray generated by dual-energy X-ray absorptiometry.

Tungsten round bars formed by isostatic pressing can improve the uniformity of the tungsten material structure that can avoid the problem of brittle fracture on tungsten wire to some extent, thereby improving its wire-wounded performance, and improve the uniformity of wire diameter and improve the finished product rate, which has good reproducibility. When use square bar molds for making tungsten bars, the binder should be added to the doped tungsten powder, so that the internal forming tungsten is easily to cause stratification and likely to cause uneven density, cracks and other phenomena. Especially during the processing of tungsten square bars, the amount of deformation the four corners of tungsten bars is large, on the other hand, its center deformation is small, so its deformation is very unevenly at a high temperature, it is easy to produce localized cracking and final affecting the quality of tungsten wire and the finished product rate.

In order to solve the problems of tungsten square bars, developing isostatic pressing way to form round tungsten bars. Hot isopressing (HIP) is a manufacturing process, theorized in the 1970s, used to reduce the porosity of metals and increase the density of many ceramic materials. This improves the material's mechanical properties and workability. During isostatic pressing, it is preferable to make certain provisions of the metal powder. Different shapes, particle size and distribution of particle size of metal powders have a significant impact on manufacturing process of tungsten bars. Therefore, average particle size of doped tungsten powder should be 2.5 ~ 5.0μm, the oxygen content is lower than 2500 × 10-6. At the time of preparation of tungsten powder, it is important to control the humidity. When the tungsten powder to be filled into a soft film sets, be sure to place the powder uniformly and intimately, do not leave any gaps, in order to ensure the quality of the final product. After the preparation is completed, the speed of the release should be slowly. But there are some problems in the process. In the high pressure liquid when pressed, the size and shape of the final product cannot be controlled. Therefore, it is better to use a metal powder automatic loading machine, so we can guarantee that the final tungsten bars are flat, smooth and uniform.

Most high-purity tungsten bars are formed by conventional vertical sintered manufacturing processes, this kind of traditional process can consume a lot of power. In addition, at the time of preparation, tungsten bar would be affected by hydrogen flow and voltage fluctuations. If the operators have insufficient professionalism or their operations have some differences in the mass-produced, which will result in different quality of products in the same batch. On the contrary, if sintering in the intermediate frequency (IF) furnace, it would not only cost the lower energy, but also has with high collection rate.

Chemical compositions of tungsten bars made by the two processes are the same. So, IF furnace sintering method can also produce highly purity tungsten bars. Compared to the traditional production method, the density and hardness of wolfram bars formed by medium frequency furnace are much higher, and distribution of its grain is uniform. Density distribution of each part of wolfram bar made by conventional sintering is parabolic state from the top down, the density of a tungsten bar has a difference of 0.37g / cm3. The density of a wolfram bar produced by IF firing only has a difference of 0.2 g / cm3, whose density distribution is more uniformity than the traditional one. Vertical furnace can only hold a tungsten bar, which would take away a lot of heat from surface because of the excessive hydrogen, resulting in the surface temperature of tungsten is lower than the core temperature. However, wolfram bar itself is heating element in medium frequency furnace, so that the core temperature will be higher than the surface temperature. Therefore, the grains of a sintered tungsten bar will be unevenly distributed. For IF sintering, it can be placed more tungsten bars which can be displayed closely, then the heat taken away by hydrogen will be relatively less. Therefore, the final products would have more uniform density distribution.

All in all, IF sintering not only has a capacity of producing a higher purity tungsten bar, but also ensures a stable quality for the manufacturing of goods in large quantities. Further, since the power consumption is low, the required cost is also less. IF sintering adopts eddy current sensor which can make crucible furnace heat and then radiation to the tungsten, so the outside and inside of tungsten bars are nearly the same, therefore the tungsten grains of cross-section are uniform.