The effect of the inlet gas pressure,supplementary gas pressure and nozzle channel dispersion angle on the pre-breakup behavior of Ti-6Al-4V(TC4)discontinuous droplets during EIGA was investigated by combining numeric...The effect of the inlet gas pressure,supplementary gas pressure and nozzle channel dispersion angle on the pre-breakup behavior of Ti-6Al-4V(TC4)discontinuous droplets during EIGA was investigated by combining numerical simulation with experiments.The results show that the axial velocity at the recirculation zone before the stagnation location was first increased and decreased then increased significantly after the peak value,while the pressure of the recirculation zone increased with the increase in inlet pressure.With the supplementary pressure increasing,the velocity magnitude and range of the recirculation zone gradually decreased.As the dispersion angle of the nozzle channel increased,the pre-breakup efficiency of droplets gradually decreased,but the adhesion phenomenon of droplets on the inner wall surface of the nozzle channel(IWSNC)gradually weakened.Under the inlet pressure of 4 MPa,a supplementary pressure of 0.05 MPa,and the dispersion angle of 15°,the uniform and spherical TC4 powders with diameter of 70μm were prepared,which was consistent with the simulation results.The optimized process parameters is a balance between the size of the pre-atomized particles and the back-spraying and bonding phenomenons of droplets.展开更多
与传统的雾化制粉技术不同,电极感应熔炼气体雾化(EIGA)技术是采用预合金棒料为电极,无坩埚感应加热,熔化后直接滴落雾化区被惰性气体雾化的技术.该技术由于在熔炼过程中液态金属与坩埚不接触,有效地减少了钛合金粉末中的夹杂物,改善了...与传统的雾化制粉技术不同,电极感应熔炼气体雾化(EIGA)技术是采用预合金棒料为电极,无坩埚感应加热,熔化后直接滴落雾化区被惰性气体雾化的技术.该技术由于在熔炼过程中液态金属与坩埚不接触,有效地减少了钛合金粉末中的夹杂物,改善了合金粉末的质量.本文利用自主设计制造的EIGA制粉设备,采用激光粒度分析仪、扫描电镜(SEM)、X射线衍射仪(XRD)等分析手段,研究了不同功率参数对雾化制备TC4合金粉末的粒度分布、组织形貌、空心球等的影响.研究表明:EIGA法制备的TC4合金粉末整体球形度均较好,空心球缺陷较少,空心球率低于3%.熔炼功率较低时,粗颗粒粉末较多,且存在一定比例不规则的棒形和哑铃状粉末颗粒;当功率提高到62 k W时,细粉比例明显提高,不规则形状的粉末颗粒基本消失.随着功率的升高,粉末中的氧含量呈增加趋势,但仍基本保持在0.08%~0.10%较低范围内.功率为56 k W时,粉末松装密度最好,为2.686 g/cm3,松装密度比为60.63%,符合激光3D打印用TC4钛合金粉末松装密度比要求.展开更多
电极感应熔炼气雾化(Electrode induction melting gas atomization,EIGA)是一种制备超洁净无夹杂物金属粉末的先进制粉技术,由于其工艺过程中不使用耐火材料并且所制备粉体具有粒径小、球形度高、无夹杂物等特点,目前已成为大规模制备...电极感应熔炼气雾化(Electrode induction melting gas atomization,EIGA)是一种制备超洁净无夹杂物金属粉末的先进制粉技术,由于其工艺过程中不使用耐火材料并且所制备粉体具有粒径小、球形度高、无夹杂物等特点,目前已成为大规模制备粉末冶金增材制造用超洁净金属粉末的重要方法。但国内对于EIGA技术引进较晚,对其工艺设计研究还未达到德国等先进国家的水平,因此,本文综述了自1991年德国ALD公司申请专利30年以来EIGA技术的发展及工艺研究现状,对EIGA技术的优点进行了汇总,归纳了EIGA技术的机理研究脉络与技术要点,并通过纵观气雾化制粉的发展历程对EIGA技术的未来发展做了展望,为粉末冶金和增材制造原材料粉末的制备提供了参考。展开更多
Super-clean and super-spherical FGH4095 superalloy powder is produced by the ceramic-free electrode inductionmelt inert gas atomization（EIGA） technique.A continuous and steady-state liquid metal flow is achieved at ...Super-clean and super-spherical FGH4095 superalloy powder is produced by the ceramic-free electrode inductionmelt inert gas atomization（EIGA） technique.A continuous and steady-state liquid metal flow is achieved at high-frequency（350 k Hz） alternating current and high electric power（100 k W）.The superalloy is immersed in a high-frequency induction coil,and the liquid metal falling into a supersonic nozzle is atomized by an Ar gas of high kinetic gas energy.Numerical calculations are performed to optimize the structure parameters for the nozzle tip.The undesired oxidation reaction of alloying elements starts at 1000℃ with the reaction originating from the active sites on the powder surfaces,leading to the formation of oxides,MexOy.The role of active sites and kinetic factors associated with the diffusion of oxygen present in the atomization gas streams are also examined.The observed results reveal that the oxidation process occurring at the surface of the produced powders gradually moves toward the core,and that there exists a clear interface between the product layer and the reactant.The present study lays a theoretical foundation for controlling the oxidation of nickel-based superalloy powders from the powder process step.展开更多
基金Funded by the National Natural Science Foundation of China(No.51627805)the Natural Scienceof Guangdong Province,China(No.2015A030312003)the Science and Technology Research Project of Guangdong Province,China(No.2014B010129003)。
文摘The effect of the inlet gas pressure,supplementary gas pressure and nozzle channel dispersion angle on the pre-breakup behavior of Ti-6Al-4V(TC4)discontinuous droplets during EIGA was investigated by combining numerical simulation with experiments.The results show that the axial velocity at the recirculation zone before the stagnation location was first increased and decreased then increased significantly after the peak value,while the pressure of the recirculation zone increased with the increase in inlet pressure.With the supplementary pressure increasing,the velocity magnitude and range of the recirculation zone gradually decreased.As the dispersion angle of the nozzle channel increased,the pre-breakup efficiency of droplets gradually decreased,but the adhesion phenomenon of droplets on the inner wall surface of the nozzle channel(IWSNC)gradually weakened.Under the inlet pressure of 4 MPa,a supplementary pressure of 0.05 MPa,and the dispersion angle of 15°,the uniform and spherical TC4 powders with diameter of 70μm were prepared,which was consistent with the simulation results.The optimized process parameters is a balance between the size of the pre-atomized particles and the back-spraying and bonding phenomenons of droplets.
文摘与传统的雾化制粉技术不同,电极感应熔炼气体雾化(EIGA)技术是采用预合金棒料为电极,无坩埚感应加热,熔化后直接滴落雾化区被惰性气体雾化的技术.该技术由于在熔炼过程中液态金属与坩埚不接触,有效地减少了钛合金粉末中的夹杂物,改善了合金粉末的质量.本文利用自主设计制造的EIGA制粉设备,采用激光粒度分析仪、扫描电镜(SEM)、X射线衍射仪(XRD)等分析手段,研究了不同功率参数对雾化制备TC4合金粉末的粒度分布、组织形貌、空心球等的影响.研究表明:EIGA法制备的TC4合金粉末整体球形度均较好,空心球缺陷较少,空心球率低于3%.熔炼功率较低时,粗颗粒粉末较多,且存在一定比例不规则的棒形和哑铃状粉末颗粒;当功率提高到62 k W时,细粉比例明显提高,不规则形状的粉末颗粒基本消失.随着功率的升高,粉末中的氧含量呈增加趋势,但仍基本保持在0.08%~0.10%较低范围内.功率为56 k W时,粉末松装密度最好,为2.686 g/cm3,松装密度比为60.63%,符合激光3D打印用TC4钛合金粉末松装密度比要求.
文摘电极感应熔炼气雾化(Electrode induction melting gas atomization,EIGA)是一种制备超洁净无夹杂物金属粉末的先进制粉技术,由于其工艺过程中不使用耐火材料并且所制备粉体具有粒径小、球形度高、无夹杂物等特点,目前已成为大规模制备粉末冶金增材制造用超洁净金属粉末的重要方法。但国内对于EIGA技术引进较晚,对其工艺设计研究还未达到德国等先进国家的水平,因此,本文综述了自1991年德国ALD公司申请专利30年以来EIGA技术的发展及工艺研究现状,对EIGA技术的优点进行了汇总,归纳了EIGA技术的机理研究脉络与技术要点,并通过纵观气雾化制粉的发展历程对EIGA技术的未来发展做了展望,为粉末冶金和增材制造原材料粉末的制备提供了参考。
文摘Super-clean and super-spherical FGH4095 superalloy powder is produced by the ceramic-free electrode inductionmelt inert gas atomization（EIGA） technique.A continuous and steady-state liquid metal flow is achieved at high-frequency（350 k Hz） alternating current and high electric power（100 k W）.The superalloy is immersed in a high-frequency induction coil,and the liquid metal falling into a supersonic nozzle is atomized by an Ar gas of high kinetic gas energy.Numerical calculations are performed to optimize the structure parameters for the nozzle tip.The undesired oxidation reaction of alloying elements starts at 1000℃ with the reaction originating from the active sites on the powder surfaces,leading to the formation of oxides,MexOy.The role of active sites and kinetic factors associated with the diffusion of oxygen present in the atomization gas streams are also examined.The observed results reveal that the oxidation process occurring at the surface of the produced powders gradually moves toward the core,and that there exists a clear interface between the product layer and the reactant.The present study lays a theoretical foundation for controlling the oxidation of nickel-based superalloy powders from the powder process step.
