The use of plasma as heat source has great technical advantages in the spheroidization treatment of micron and submicron and some nanomaterials. Rf plasma torch arc body large, stable arc current, easy to adjust and control, making it easy to be used in the field of ultra-fine powder material treatment technology. At present, the technology of using plasma to treat powder abroad has a certain level of technology. Southwest Institute of Physics of nuclear industry in China has adopted self-built plasma spheroidization system to realize the spheroidization of powder such as W and Al2O3, with high spheroidization rate and size up to...... 5 ~ 45 m. The powder is used for thermal spraying and powder metallurgy, with good performance.
Because of the excellent application of spheroidizing powder in some fields, the spheroidizing of all kinds of powder, especially the refractory powder, becomes the requirement of powder preparation. Niobium is a highly refractory metal with a melting point of up to 2,740 °C. It can absorb gas and is used as a degassed agent. It is also a good superconductor for many high-tech applications. For example, in the field of high energy physics, niobium products with high performance and large inches are needed. If niobium products are prepared by using laser 3D printing technology, it is possible to obtain products with better performance and larger size compared with traditional processes. However, in the case of laser 3D printing of dense and high-performance niobium products, the irregular particle shape powder is used, which has poor fluidity during printing and paving, resulting in slow printing rate, small accumulation density, easy to form holes, and not dense. If the spherical powder is used as the raw material of niobium powder, it has good fluidity, high accumulation density, uniform shrinkage after laser sintering, which can realize more accurate size control, uniform product density, low porosity and densification, greatly reducing the preparation time and laser sintering power. Moreover, the impurity content can be further reduced by rf plasma spheroidal powder, especially the content of trace oxygen impurity, so as to further optimize the superconducting electric property of niobium products. Under this background, a feasible and productive method is needed for the preparation of micro - fine spherical niobium powder.
The advantages are that, compared with the original powder with irregular particle shape, most of the powder particles are spherical, with higher fluidity, particle density and purity, smooth surface and low porosity. This invention method changed the shape of a niobium powder particles, spheroidization rate is high, at the same time improve the purity of niobium powder, and increase the apparent density of the powder, increased the niobium powder flow, improved the physical properties of the niobium powder, at the same time will not change the phase of niobium powder, is advantageous to the compact powder molding and sintering, 3 d printing of applications such as high-performance niobium products, dense coating, and low cost, can achieve very high added value. Compared with other patents related to the spheroidization of niobium alloy powder, the pure niobium powder used in the present invention has a high melting point, the spheroidization of niobium powder improves the purity at the same time, and has a certain powder spheroidization productivity.
