Design And Process Research Of Plasma Coaxial Wire Feeding Atomization Pulverizing Equipment

Titanium and titanium alloys are widely used in aviation,aerospace,navigation,automotive,medical and other fields because of their excellent properties such as high strength,low density,good mechanical properties,non-magnetic,toughness and corrosion resistance.In recent years,based on the forming technology of titanium and titanium alloy powder has entered a stage of rapid development,and the purity of titanium and titanium alloy powder,sphericity,liquidity,inclusions,gas content,particle size and particle size distribution is important factor to determine the level of titanium and titanium alloy forming technology,is also the foundation for development of advanced forming technology of titanium and titanium alloy.Therefore,in order to prepare low cost and high quality titanium powder as the research purpose,the plasma melting technology and gas atomization technology were simulated by numerical simulation method.On the basis of plasma atomization,coaxial wire feeding is adopted,and the atomization equipment of plasma coaxial wire feeding is designed.The preparation process of titanium powder was studied by using the self-designed plasma coaxial wire feeding atomizing powder preparation equipment,and the effects of various process parameters on the particle size and size distribution of titanium powder,as well as the effects of particle size on the surface morphology of titanium powder were analyzed.Finally,titanium powder with low cost and high quality was successfully prepared.The main research results are as follows:Four cathode nozzles with different inner diameters were designed.The melting law of plasma and titanium wire was analyzed by using multi-physical field coupling simulation software COMSOL Multiphysics5.6.The structure of cathode nozzles was optimized,and the inner diameter of cathode nozzles after optimization was 4.8mm.Through numerical simulation,it is found that the temperature of plasma will increase with the increase of current intensity.When the current intensity exceeds 60A,the maximum temperature of plasma will reach 10~4K and the outlet temperature will also exceed 8.0×10~3K.At the same time,the plasma shrinks to a certain extent when the inlet velocity of argon gas increases,but the maximum temperature is above 8.0×10~3K in general.The temperature distribution of plasma has an obvious effect on the melting of titanium wire.The higher the temperature is,the more heat absorbed by titanium wire and the faster the melting speed of titanium wire.The atomizer structures with different extension and different angles are designed respectively,and the finite element analysis software Fluent19.2 the gas atomization structure model is established,and the effects of atomizer extension and atomizer angle on atomization gas flow field are analyzed.It is determined that the optimal atomizer extension is 2mm and the atomizer angle is 36°.On this basis,the influence of atomizing argon inlet pressure on single-phase gas flow field and gas-liquid two-phase flow field is analyzed.When the atomizing speed of argon is large,it is conducive to the effective atomization of titanium liquid by argon and improve the quality of powder.After the introduction of titanium liquid,the titanium liquid will collide with argon in the reflux area,and affect the gas flow field,resulting in the deformation of the reflux area.Based on the numerical simulation results,a plasma coaxial wire feeding atomizing powder preparation equipment was designed,and the process of plasma coaxial wire feeding atomizing powder preparation was studied.The optimal process parameters were determined as follows:current intensity 40A,atomizing argon pressure 4MPa,wire feeding speed0.01m/s.Under the process parameters,the yield of fine powder(≤50μm)could reach47.99%.Powder surface finish is good,there is basically no satellite powder,high sphericity.