What Is Tungsten Powder?
Since tungsten has the highest melting point of any metal, it cannot be refined from ore by conventional smelting. Chemical processes are used to separate tungsten from ore. To produce ammonium para tungstate, ores are crushed, roasted, and/or subjected to several chemical reactions, precipitations, and washings, depending on the manufacturer and the composition of the ore (APT). APT can be used to make tungsten oxide or marketed commercially. To produce pure tungsten powder with water as a byproduct, tungsten oxide can be heated in a hydrogen atmosphere. The raw material for tungsten mill products, including wire, is tungsten powder.
With Pure Tungsten Powder In Hand, How Do We Create Wire?
Sifted and combined tungsten powder is used. You may include a binder. Weighing and loading a set quantity into a steel mold before it is fed into a press. The powder is compressed into a sturdy-looking but delicate bar. The bar is removed after disassembling the mold.
The delicate bar is loaded into a vessel made of refractory metal and placed within a furnace with a hydrogen environment. As a result of the high temperature, the material starts to unite. Material has minimal to no grain development and is roughly 60% to 70% dense.
3. Full Sintering
In a unique water-cooled treatment bottle, a whole sintering bar is loaded. The bar will get an electrical current. The heat produced by this current will cause the bar to decrease by around 15% and density to between 85% and 95% of its full density. The bar also starts to produce tungsten crystals.
At room temperature, the tungsten bar is extremely brittle but now strong. By increasing its temperature to between 1200°C and 1500°C, it can be rendered more flexible. The bar can be fed through a swager at this temperature. A swager is a machine that uses a die that hammers a rod with around 10,000 blows per minute to shrink the diameter of the rod. A swager typically shrinks the diameter by 12% per pass. Swaging causes the crystals to grow longer and develop a fibrous texture. At this point, the rod needs to be stressed-relieved by reheating, even though this is desirable in the end product for ductility and strength. Swaging continues until the diameter of the rod reaches.25–.10 inches.
Now it is possible to draw swaged Tungsten Wire through dies to shrink the diameter to about.10 inches. Lubricated wire is dragged through diamond or tungsten carbide dies.
The precise chemical and the wire’s intended purpose will determine how much of its diameter is reduced. The fibres re-extend when the wire is drawn, and the tensile strength rises. The wire may need to be annealed at some points in order to facilitate processing. A wire’s diameter can be reduced to.0005 inches.