The Development Of Equipment For Producing Metal Powder By Electrical Explosion Wire And Preparing Tantalum Powder

Metal powder has a broad application prospect in military industry,aviation,medicine and other fields.The metal powder produced by wire electric explosion has the advantages of controllable particle size distribution,simple production process and zero pollution.Metal powder has the characteristics of high sphericity,high purity and high activity.It is a promising industrial preparation method of metal powder.Based on the principle of gas discharge,the equipment of metal powder production by wire electric explosion with wire tray and wire feeding was developed.The motor and transmission device are placed outside the electric explosion chamber to save the internal space.The electric explosion chamber can accommodate two sets of electric explosion devices to work at the same time,so as to improve the output of metal powder.The tail shaft seal is used to transfer the power,so as to avoid the oxidation of metal powder caused by the air entering the cavity,and the metal aerosol does not enter the air at the same time.The contact between the cycloid and the paddle drives the wire clamping mechanism on the wire carrier to clamp the metal wire and send it into the high-voltage electric field to realize the continuous electric explosion.Based on the principle of ablation material constraint,the position of the wire clamped by the liner bar and the compression bar changes constantly,which can slow down the ablation of the device by the arc and improve the service life.The coaxial electrode is designed to reduce the loop inductance.The high voltage electrode is connected with a flexible structure,and the grounding electrode can rotate freely.The whole electrode is not perpendicular to the ground,reducing the amount of metal powder adhered to the electrode and slowing down the impact of explosion shock wave on the electrode.The oil medium isolating switch and solid isolating switch installed in the high voltage end of the energy storage capacitor are developed.The transformer oil,outer electrode and polyethylene sheet are seriously ablated in the operation of the two switches,and their service life is short.Using the self-developed equipment to carry out the electrical explosion test of tantalum wire under different process parameters.By observing the morphology of the micron powder,it is found that the micron powder with smaller particle size adheres to the surface of the rice powder with larger particle size after agglomeration,and the tantalum rice powder is in the shape of droplet,globular and multilateral particles.Due to the impact of shock wave,the surface of micron particles with larger particle size has a small bulge of 1 ~ 2nm.In the first half period of the oscillating current,the current and voltage waveform vaporized and broke down,then entered the plasmadischarge stage,and the current was continuous.In the ohmic heating stage,the voltage first decreases and then increases,and the extreme voltage waveform of plasma oscillation decreases.The energy deposition density of tantalum wire is between melting heat and sublimation heat.The liquid metal will explode when it is not completely gasified.The explosive products coexist in different energy states.The liquid component condenses into micro rice flour and the gas component condenses into nano rice flour.Increasing the initial voltage can increase the density of energy deposition per unit volume of wire,decrease the average particle size of micron powder,and narrow the range of particle size distribution.When the initial voltage is too high,the energy deposition density increases correspondingly,and the particle size distribution range of micron powder becomes wider,and the particle size at the concentration of particle size distribution becomes larger.When the initial voltage is 12~15kV,the size range of tantalum powder is 8~20?m.When the initial voltage is 10 kV,the size range of tantalum powder is 30-85?m.With the increase of initial voltage,the average grain size tends to a stable value,and the influence of voltage on the average grain size weakens.The average grain size of tantalum micro rice powder is 15?m.