Molybdenum powder prepared by traditional technology is often used to be raw material of molybdenum sintered products, the common preparation methods include reduction method, fluidized bed reduction method, hydroxyl thermal decomposition method etc.

Large-size tungsten-based heavy alloy has a series of advantages including high density, low coefficient of thermal expansion, good oxidation resistance and corrosion resistance, etc. In fields of aerospace, electronic information and so on, large-size and high performance tungsten-based heavy alloy is in urgent need. Find the rule of internal structure of large-size tungsten based high specific gravity alloy during liquid phase sintering process to obtain high homogeneity, high performance and parts of large-size tungsten based high specific gravity alloy.

The cost of traditional high density tungsten alloy is high, as 3C industry begins to use small-size high density W-alloy part as counterweight material, higher requirement is put forward for the forming technology of high density W-alloy. Therefore metal powder injection molding (MIM) technology appears, it is a new near net forming technology for part, which combines plastic injection molding technology with powder metallurgy technology, it can effectively promote the wide use of high density W-alloy materials in 3C and other high-tech industries.

High density tungsten alloy has excellent mechanical property, anti burning property and absorption ability to radiation. Therefore, it is used in explosive parts such as armor piercing bomb. Normally, the part should keep well after impacted by the front end explosion, but in the test, the component breaks without external force.

Tungsten carbide (chemical formula WC) is the compound made up of tungsten and carbon, following will show the preparation procedure. The molecular formula is WC and the molecular weight is 195.85, which is black hexagonal crystal with metallic luster and has similar hardness to diamond. It is a good conductor of electricity and heat.

Molybdenum carbide (chemical formula MoC) has the characteristics of high melting point, hardness, good thermal, fine mechanical stability and excellent corrosion resistance.

With the development of chemical engineering technology, there are a series of synthesis methods used to produce nanometer scale pure molybdenum carbide (chemical formula MoC) , the followings are five common preparation methods:

Impurity elements in tungsten alloys include H, O, C, N, P, S, and Si. Because these elements have small atomic radii, and strong diffusivity in alloys, they are more likely to be in the grain boundaries and phases. Segregation occurs in places with higher energy such as the boundary, and the increase in value generates brittle phases, thereby reducing the performance of the alloy and influence tungsten alloys properties.

Tungsten electrodes tip shapes can be flat, sharpened or rounded. Flat tip is cut by grinding wheel, molybdenum wire or machining. Sharpening is much more difficult. And both shapes and welding current will influence the life time of electrodes.

During the process of nanostructured WO3 synthesis it is found that citric acid content, system pH value before hydrothermal synthesis, hydrothermal reaction temperature and hydrothermal reaction time will have great influence on the product, therefore the following will focus on several influence factors affecting the phase and morphology of nanostructured WO3.