The preparation method of pure vanadium wire utilizes electron beam melting and continuous electrolytic polishing techniques. The resulting vanadium wire exhibits high purity, excellent mechanical properties, and good surface quality. This method reduces the content of trace element impurities in vanadium metal, improving the mechanical and processing properties of vanadium materials. The vanadium wire has a purity of 99.9%, a tensile strength ≥725 MPa, an elongation ≥7.6%, and a surface roughness Ra0.2, making it suitable for nuclear testing and 3D printing.
Vanadium, often referred to as a "metallic vitamin," is widely used in aerospace, steel, chemical, pharmaceutical, and nuclear industries due to its excellent physicochemical properties, making it a rare metal of significant strategic importance worldwide. Vanadium exhibits typical low activation characteristics. High-purity vanadium possesses good plasticity, ductility, and corrosion resistance, along with advantages such as low neutron radiation activity, high heat transfer rate, low coefficient of thermal expansion, excellent high-temperature strength, and resistance to radiation swelling. Therefore, it has become a candidate material in the nuclear power field.
Therefore, research has been conducted both domestically and internationally on high-purity vanadium preparation technology and the mechanical properties and microstructure characteristics of pure vanadium at high temperatures. In particular, vanadium wire for neutron detection is a key material for self-sufficient energy detectors, requiring a purity of V ≥ 99.8% and mechanical properties including tensile strength ≥ 600 MPa and elongation ≥ 5%. Currently, the purity, mechanical properties, and surface quality of commercially available high-purity vanadium wire are insufficient to meet the application requirements of self-sufficient energy detectors.
The preparation method of high-purity vanadium wire includes the following steps:
1) Vanadium powder pretreatment: Vanadium powder is added to a 30wt% HNO3 solution and stirred until a slurry is formed. It is then washed with deionized water until the solution is neutral, at which point rinsing is stopped. Following this, it is vacuum dried to obtain pretreated vanadium powder.
2) Pressing: The pretreated vanadium powder obtained in step 1) is pressed into a fixed shape of metallic vanadium. The pressing pressure is 200 MPa to 280 MPa, and the holding time is 60 to 120 seconds.
3) Vacuum sintering: The metallic vanadium obtained in step 2) is sintered in a vacuum furnace and cooled with the furnace.
4) Electron beam melting: The sintered metallic vanadium is slowly fed into the electron gun bombardment zone of an electron beam melting furnace. The furnace is evacuated to a vacuum of 10-3 Pa to 10-4 Pa. When the vanadium molten metal drips into the bottom pad of a water-cooled copper crucible, it is slowly spirally pulled down to form a vanadium ingot, and then the outer layer is peeled off.
5) Forging with a cladding: The vanadium ingot obtained in step 4) 6) Forging with a sheath: Heating temperature 900℃～1100℃, holding time 8min～15min, initial forging temperature 1000℃～1100℃, final forging temperature 850℃～950℃, to obtain vanadium metal rods;
7) Rotary forging: Rotary forging the vanadium metal rods obtained in step 5): Single-pass deformation rate 10%~15%, heating temperature 1000℃～1100℃, heating time 3min～7min, to obtain vanadium wires;
8) Drawing: Cold drawing of the rotary forged vanadium metal rods, single-pass deformation amount 5%～15%, when the cumulative deformation amount reaches 40%～60%, vacuum annealing, drawing to fine vanadium wires φ1.0mm～φ1.5mm;
9) Continuous electrolytic polishing and cleaning: Continuous electrolytic polishing and cleaning of the fine vanadium wires obtained in step 7) in a NaOH solution with an alkaline concentration of 5%～10%wt, electrolytic current 5A～10A, wire take-up speed 3～5m/min. 9) Annealing treatment: Vacuum annealing temperature 800℃～900℃, holding time 15min～20min, followed by furnace cooling to obtain high-purity vanadium wire.
