As a representative of refractory metals, tungsten (W) and rhenium (Re) can be combined to form tungsten-rhenium alloy powder. More specifically, proper amount of rhenium can be dissolved in tungsten to form solid solution alloy powder. According to the different appearance shape, W-Re powder can be divided into spherical tungsten-rhenium alloy powder and irregular tungsten-rhenium alloy powder. It is worth noting that as science and technology mature, the market demand for the former gradually increases.
In terms of physical and chemical properties, the average particle size of tungsten-rhenium alloy powder is between 2.0-4.0um, and it has the characteristics of high melting point, high recrystallization temperature, high thermal potential, high resistivity, corrosion resistance, good plasticity, excellent creep resistance at high temperature, weldable and machined. In a certain range, with the increase of rhenium content, the comprehensive properties of the alloy become better.
In terms of production process, the steps of preparing spherical W-Re alloy powder include:
1) ingredients: a certain amount of ammonium paratungstate and ammonium rhenate;
2) Mixing: prepare a solution of ammonium paratungstate and ammonium rhenate, dry and crystallize;
3) Reduction: The mixed crystals are reduced to tungsten-rhenium alloy powder in the hydrogen environment;
4) Molding: load w-Re alloy powder into the mold, cold isostatic pressing molding;
5) Sintering: The product in step 4 is heated, insulated and sintered in hydrogen atmosphere to obtain tungsten-rhenium alloy rod billet;
6) Processing: the billet shall be processed by rotary forging, straightening and peeling, etc.
7) Spherical tungsten-rhenium alloy powder can be prepared by plasma rotary atomization.
Uses, one is in many cases, can replace pure tungsten, tungsten lanthanum, tungsten-cerium, doped tungsten and other tungsten materials as electrode or filament; The second is for high temperature parts, such as spacecraft nozzle and nozzle, vacuum furnace heat shield, etc.
