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Preparation method of tungsten powder

About tungsten powder
Tungsten powder is a metallic luster of gray-black metal (body-centered cubic crystal). The melting point is 3400 ℃. The boiling point of 5555 ℃. The hardness of tungsten is the hardest among metals, the hardness of sintered tungsten bar is 200 ~ 250, and the hardness of rotary hammer tungsten bar is 350~400. A mixture of nitric acid and hydrofluoric acid. Fused with a mixture of sodium hydroxide and sodium carbonate. Tungsten powder slightly soluble in nitric acid, sulfuric acid, aqua regia; Insoluble in water, hydrofluoric acid, potassium hydroxide. There are two types of tungsten, A and B. Type A is a stable body-centered cubic structure at standard temperatures and pressures. Type B tungsten can only be present in the presence of oxygen. It is stable below 630 ° C and converted to A-tungsten above 630 ° C, and this process is irreversible.
Preparation method of tungsten powder
Tungsten powder is prepared by hydrogen reduction of tungsten trioxide or ammonium para tungstate. The process of preparing tungsten powder by hydrogen reduction method is generally divided into two stages: the first stage is at the temperature of 500 ~ 700℃, tungsten trioxide is reduced to tungsten dioxide; In the second stage, tungsten dioxide is reduced to tungsten powder at the temperature of 700 ~ 900℃. Reduction reactions are usually carried out in tubular or rotary furnaces.

The properties of reduced tungsten powder (such as purity, particle size, particle size composition, etc.) mainly depend on the reduction process. In the process of reducing tungsten powder in the tubular furnace, the main technological parameters affecting the reduction rate are reduction temperature, the loading capacity of tungsten oxide in the firing boat, the moving speed of the firing boat, the flow rate of hydrogen and the moisture content in hydrogen. With the increase of reduction temperature, the grain size of tungsten powder becomes coarser.
In addition to the hydrogen reduction method, there are early tungsten oxide carbon reduction methods, reduction temperature is higher than 1050℃. The tungsten powder obtained by this method is of low purity. In addition, the process of reducing tungsten oxide with metals such as aluminum, calcium and zinc is also in progress. For special applications requiring high purity, ultra-fine size of tungsten powder, tungsten chloride hydrogen reduction method has been developed, the size of tungsten powder can be less than 0.05μm.
Reduction of tungsten trioxide by hydrogen
Hydrogen reduction can be carried out in two stages. In the first stage, tungsten trioxide is heated to 550 ~ 800℃ and reduced with hydrogen. In the second stage, tungsten powder is produced at 650 ~ 850℃.
You can also first reduce ammonium para tungstate to blue tungsten oxide (blue tungsten) through hydrogen or without hydrogen, and then reduce to tungsten powder with hydrogen. The particle size and composition of tungsten powder are important quality indexes of tungsten powder. Reduction is carried out in tubular or rotary electric furnaces.
Tungsten powder supplier
As a global Tungsten powder powder supplier, Tanki New Materials Co.Ltd has rich experiences in the properties, applications, and cost-effective manufacturing of advanced and engineered materials. Tanki New Materials Co.Ltd Aims to help All industries and Chemical Wholesalers to find high-quality, cheap price Nanomaterials and chemicals by providing turn-key customize manufacturing services. If you are looking for Tungsten powder, please feel free to send an inquiry for the latest Tungsten powder price.
 

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