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Technological innovation

Technological innovation

The main required attention technical points during the preparation of tungsten heavy alloy

Tungsten heavy alloy, also known as tungsten heavy alloy, tungsten heavy alloy, its density is higher, greater than or equal to 16.5 g/cm3. At present, the tungsten heavy alloy is not only widely used in aviation, aerospace, military fields, also been used in the field of civilian industry frequently. In the process of preparing tungsten heavy alloy, main technical points need to pay attention to the following:

1 Composition design

The elements of tungsten heavy alloy except W (content in 85-98%), other more content elements is Ni, Fe, Cu, etc. In addition we can join Mo, Ta, La and Re elements or compounds in the process of preparation. Each element to join will make the tungsten heavy alloy has better physical and chemical properties, so that tungsten heavy alloy products get more extensive application. Different content of each element, also makes its products show different performance, accurately grasp the elements content will help to improve the technical specifications of the tungsten heavy alloy.

2 Milliing

To the preparation of excellent mechanical properties of tungsten heavy alloy. At the first, tungsten powder must have  high purity, small particle size and uniformity. Currently nanometer powder is a research hotspot, has the following two basically categories:

1) Spray drying method

Spray drying method is the preferred a certain ingredients of raw salt solution, salt solution including tungstate and metal chloride, solution generated after atomization droplets. Due to the small droplets rapid solvent evaporation and rapid deposition of the solute, crystallization was uniform chemical composition of powder

2) Mechanical alloying method

Mechanical alloying method is to choose a certain proportion of tungsten heavy alloy balls into the ball mill, the initial powder and metal powder under the action of metal ball is not uniform, after cold welding many times, such as deformation, the resulting organization is small, its composition is relatively homogeneous composite powder

3) Forming

More traditional tungsten heavy alloy die forming, the forming process of a new alternative of extrusion forming, powder injection molding process is powder. After the two methods on the preparation of complex shape parts has significant advantages, the production principle is to tungsten heavy alloy powder mixed with forming agent, extrusion injection into the forming machine. Because of the addition of forming agent, extrusion, powder injection molding powder has a wide applicability

4) Sintering

Due to the solid phase sintering process on the size of the original powder alloy is higher, the liquid phase sintering, the sintering time is long, and easily lead to collapse and deformation. Integrated the advantages and disadvantages of the two, and put forward the solid phase sintering and two step sintering process of liquid phase sintering. Because the two step sintering deformation is small, tungsten heavy alloy organization get more uniform, materials will greatly improve performance, so the two step sintering are more widely used. In addition, in recent years developed a new microwave sintering as well as the discharge plasma sintering technology is also in the promotion and use