Simulation Of Atomizing Spherical Tantalum Powder By Plasma Wire

Tantalum has been recognized as an ideal orthopedic implant material for its excellent biocompatibility.However,it is difficult to fabricate tantalum into orthopedic implants,which limits its development.Powder Bed Fusion(PBF)is the fastest developing and most widely used metal additive manufacturing technology,which can greatly improve the forming quality of tantalum metal.However,the quality of spherical tantalum Powder used in PBF technology is high,and the problems of low yield of fine Powder and low sphericity exist in conventional preparation methods.Plasma wire atomization is a new technology with good sphericity and high yield of fine powder,but this technology has been monopolized by foreign countries and little research has been carried out in China.Therefore,the preparation of PBF spherical tantalum powder is of great significance to the development of tantalum in the medical field.In this paper,the preparation process of spherical tantalum powder by plasma wire atomization is studied.The plasma generator,the core component of the equipment,and the key atomization process are studied by numerical simulation.On the basis of numerical simulation,the experimental verification of atomization of tantalum powder by plasma wire is carried out.Firstly,the DC plasma generator was numerically simulated by FLUENT,and the UDF(User-defined Function)program was written according to the secondary development of Maxwell's equations.The influence of key process parameters on the plasma torch outlet velocity and temperature was simulated.The parameters of the optimized DC plasma generator were obtained by orthogonal experiment.Secondly,the plasma wire atomization flow field model was built,and the change process of liquid flow breakage in the unidirectional flow field and gas-liquid two-phase flow field in the atomization process was analyzed.The included atomization Angle was determined,and the structural characteristics of atomization flow field were revealed,which laid a foundation for the subsequent atomization test.Finally,on the basis of the numerical simulation of the dc plasma generator and the key atomization process,the experimental verification of the atomization of tantalum powder by plasma wire was carried out,and the characteristics of the prepared spherical tantalum powder were characterized and analyzed.Through the above research,the optimized process parameters range was obtained:the working current was 80-200 A,the air inlet flow was 60-150L/min,the nozzle outlet diameter was 7mm,and the included atomization Angle was 30.The average particle size of spherical tantalum powder prepared by this process is 36.5?m,the yield of fine powder is 62.8%,the powder morphology is spherical,the powder surface is smooth and the sphericity reaches 99%,which is better than the conventional method of spherical tantalum powder prepared by PBF technology requirements.