Intermediate frequency sintering is mainly applied in powder metallurgy process, especially in producing the relatively large workpieces or requiring for a higher firing temperature, and then the firing method must be used. Wolfram is often used as firing equipment for intermediate frequency sintering, since the high melting point of wolfram which just below the melting point of the carbon. In addition, in case of high temperature, wolfram still has a high mechanical strength and hardness. Therefore, nowadays, the intermediate frequency firing furnace main adopt tungsten crucible.

The process of firing mainly through five steps: preparation of raw materials, shake raw materials evenly. After mixing, assort the materials in a proper proportion. Mixing those raw materials and pelletizing them. Furthermore, spread the firing materials on the firing pallet for firing. Finally, freeze the finished product. Under the conditions of the high temperatures produced by fuel and a series of chemical reactions of tungsten granules, some soluble materials of mixture would soften and partially melt, producing an amount of liquid, wetting particles which are not melted. In the cooling process, the liquid will paste particles into a massive form, this process is called firing.

Wolfram crucible is commonly formed by welding and powder metallurgy technology with inert gas. The thickness of the wolfram crucible formed by welding is generally less than 3 mm, life time and heating performance of this type of wolfram crucible are not as good as wolfram crucible which is made by powder metallurgy technology. Wolfram crucible for firing can ensure that the uniformity furnace temperature and the fast speed for heating. Therefore, wolfram crucible is one of the necessary equipment for the firing process. Wolfram crucible has a longer life which has a less impact on the environment, and it can be repeatedly used to control environmental pollution produced by firing.

Control of temperature is very important to the firing process, since grain-boundary diffusion and volume diffusion rely heavily upon temperature, the size and distribution of particles of the material, the materials composition, and often the firing environment to be controlled. When using wolfram crucible for firing, users should pay attention to improve the production installed furnace conditions in order to avoid negative phenomena, such as sliding produced by controlling the shrink of lower part of wolfram crucible, which has a great impact on avoiding producing waste and defective products.

Sapphire single crystal growth furnace often works with wolfram products which produce production by 99.95% purity of tungsten raw materials, including wolfram crucible, wolfram plate, wolfram sheet, wolfram electrode shield, wolfram tube, wolfram heat shield and other wolfram products. Thanks to the highest melting point of all metals, wolfram crucible is widely applied in sapphire single crystal growth furnace.

It is uncommonly to use wolfram crucible itself as the heating element for single crystal growth furnace, and wolfram crucible would volatize wolfram atoms at high temperatures. It is also possible to adopt wolfram crucible itself as a heat element, but the choice of the manufacturing process and the setting of operation temperature are the most critical factors. Due to differences in manufacturing process of wolfram crucible, sapphire single crystal growth furnace generally use sintering tungsten crucible in China.

Characteristic of tungsten crucible for sapphire growth is that wolfram crucible can avoid sticking the pot. During the process of sapphire single crystal growth, it is easy to stick the pan, but wolfram crucible is high temperature resistant refractory metal which is difficult to produce the chemical reaction. So wolfram crucible can protect purity of sapphire well. Sapphire growth by kyropoulos method requires for a better temperature field device, the quality of spinning wolfram crucible is excellent, the purity and density is relatively high, but prices are high.

On the other hand, wolfram crucible cannot be placed immediately on a cold metal table after heating, otherwise it will crack. Most of the thickness of the wolfram crucibles are relatively thin which is not conducive to long-term using, the number of reusing is poor which will increase the cost of sapphire single crystal growth.

As an important technology, sapphire crystal has been widely used in many fields of science and technology, defense and civilian industries, electronic technology. Chemical properties of sapphire crystal are very stable which would not dissolve in water. In addition,  it would not corroded by acid and alkali, only at a higher temperature (300 ℃) can it be corroded by hydrofluoric acid, phosphoric acid and molten potassium hydroxide eroded. Therefore, the choice of wolfram crucible for a sapphire single crystal growth furnace should base on the manufacturing process of sapphire single crystal and the conditions of single crystal sapphire single crystal growth furnace.

Tungsten alloy shielding plays an important role in the field of radiation protection with its great radiation shielding effectiveness. Radiation protection, sometimes known as radiological protection, is defined by the International Atomic Energy Agency (IAEA) as "The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this". Its main tasks are to protect the health and safety of personnel engaged in radiation work, public and their descendants, to protect the environment, and to promote the development of atomic energy industry. The main content of the radiation protection consists of standards for radiation protection, radiation protection evaluation, radiation dosimetry, technology of radiation protection and radiation protection management. The factors of radiation protection include time, distance and shielding. Shielding means set a shielding material between the radiation source and the body to attenuate the intensity of radiation, thereby reducing the radiation levels.

Radiation is often classified as either ionizing radiation or non- ionizing radiation depending on the energy of the radiated particles. Ionizing radiation is radiation that carries enough energy to free electrons from atoms or molecules, thereby ionizing them. The common ionizing radiations are α particles, β particles, protons, neutrons, X rays, and γ rays. While non- ionizing radiation has lower energy than ionizing radiation and does not ionize atoms or molecules. For people involved with the radiation work, radiation hazards will occur when not take protective measures to protect body from being irradiated with a dose of radiation. Radiation can cause radiation sickness, making lesions in almost all human organs and systems (including the nervous system, blood-forming organs and the digestive system). And it can also cause acute radiation injury due to a certain dose of radiation exposition in a short time and chronic radiation injury whose irradiation time is longer. Chronic radiation injury will lead to skin damage, weakened immunity, impaired fertility and so on.

There are a many types of tungsten alloy shielding, including tungsten alloy shielding tank, tungsten alloy shielding container, tungsten alloy shielding cover, tungsten alloy shielding shell. Because the radiation shielding properties of a metal material increases with the increasing of its density, and tungsten alloy has great density, tungsten alloy shielding therefore has excellent radiation shielding capability and absorption capacity. Putting a tungsten alloy shielding between the body and the radiation source can effectively reduce the radiation intensity to avoid radiation damage.