Tungsten alloy, also called w-base high proportion alloy, its density is higher, greater than or equal to 16.5 g/cm3. W-base high proportion alloy not only at present, is widely applied in military fields such as aviation, aerospace, weapons, also more and more been used in the field of civilian industry. In the process of preparing tungsten high proportion alloy was the main technical points need to pay attention to the following:
1, w-base high proportion alloy composition design, in addition to the W (content in 85-98%), other content is more elements Ni, Fe, Cu, etc.). In addition will also join in the process of preparation of Mo, Ta, La and Re elements or compounds. Of each element to join will make the tungsten alloy has better physical and chemical properties, so that tungsten alloy products get more extensive application. Different content of each element, and also makes its products show different performance, accurately grasp the elements content will help to improve the technical specifications of the tungsten alloy.
2, flour to the preparation of excellent mechanical properties of tungsten alloy, tungsten powder, you must first have high purity, small particle size and uniformity of good characteristics, nanometer powder is currently research hotspot, basically has the following two 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 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 a more traditional tungsten 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 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 + two step sintering process of liquid phase sintering. Because the two step sintering deformation is small, tungsten 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.
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