It was attempted to enhance and accelerate the separation of oxidation inclusions from magnesium alloy melt by virtue of ultrasonic agglomeration technology.In order to investigate the feasibility and effectiveness of...It was attempted to enhance and accelerate the separation of oxidation inclusions from magnesium alloy melt by virtue of ultrasonic agglomeration technology.In order to investigate the feasibility and effectiveness of standing waves for ultrasonic purification of magnesium alloy melt,numerical simulation and relevant experiment were carried out.The numerical simulation was broken into two main aspects.On one hand,the ultrasonic field propagations within the cells with various shapes were characterized by numerical solutions of the wave equation and with a careful choice of geometry a nearly idealized standing wave field was finally obtained.On the other hand,within such a standing wave field the agglomeration behavior of oxidation inclusions in magnesium alloy melt was analyzed and discussed.The agglomeration time and agglomeration position of oxidation inclusions were predicted with numerical simulation method.The results show that the oxidation inclusions whose apparent densities are close to the density of the melt can agglomerate at wave nodes in a short time which to a great extent enhances and accelerates the separation of oxidation inclusions from magnesium alloy melt.展开更多
The oxidation behaviour of molten ZK60 and ME20 magnesium alloys in 1% 1,1,1,2-tetrafluoroethane/air atmospheres at 720 °C was compared with that of molten magnesium. The oxidation kinetics of these three melts w...The oxidation behaviour of molten ZK60 and ME20 magnesium alloys in 1% 1,1,1,2-tetrafluoroethane/air atmospheres at 720 °C was compared with that of molten magnesium. The oxidation kinetics of these three melts was determined by thermograyimetric measuring instrument, and the surface films of the oxidized samples were examined by scanning electron microscope (SEM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The results show that the oxidation rate of molten ZK60 or ME20 alloys is much lower than that of molten magnesium in 1% 1,1,1,2-tetrafluoroethane/air atmospheres. The surface film formed on the molten magnesium is composed of MgF2, MgO and C, while the film formed on ZK60 melt mainly consists of MgF2, MgO, C and some ZrF4, and the film on ME20 mainly consists of MgF2, MgO, C and a small amount of CeF4. The good oxidation resistances of ZK60 and ME20 alloy melts may be caused by their major alloying elements Zr and Ce, respectively.展开更多
基金Projects(2007CB613701,2007CB613702)supported by the National Basic Research Program of ChinaProjects(50974037,50904018)supported by the National Natural Science Foundation of ChinaProject(NCET-08-0098)supported by the Program for New Century Excellent Talents in University of China
文摘It was attempted to enhance and accelerate the separation of oxidation inclusions from magnesium alloy melt by virtue of ultrasonic agglomeration technology.In order to investigate the feasibility and effectiveness of standing waves for ultrasonic purification of magnesium alloy melt,numerical simulation and relevant experiment were carried out.The numerical simulation was broken into two main aspects.On one hand,the ultrasonic field propagations within the cells with various shapes were characterized by numerical solutions of the wave equation and with a careful choice of geometry a nearly idealized standing wave field was finally obtained.On the other hand,within such a standing wave field the agglomeration behavior of oxidation inclusions in magnesium alloy melt was analyzed and discussed.The agglomeration time and agglomeration position of oxidation inclusions were predicted with numerical simulation method.The results show that the oxidation inclusions whose apparent densities are close to the density of the melt can agglomerate at wave nodes in a short time which to a great extent enhances and accelerates the separation of oxidation inclusions from magnesium alloy melt.
基金Project (SJ08-ZT05) supported by the Natural Science Basic Research Plan in Shaanxi Province of ChinaProject (ZK1050) supported by the Key Scientific Research Plan of Baoji University of Arts and Science, China
文摘The oxidation behaviour of molten ZK60 and ME20 magnesium alloys in 1% 1,1,1,2-tetrafluoroethane/air atmospheres at 720 °C was compared with that of molten magnesium. The oxidation kinetics of these three melts was determined by thermograyimetric measuring instrument, and the surface films of the oxidized samples were examined by scanning electron microscope (SEM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The results show that the oxidation rate of molten ZK60 or ME20 alloys is much lower than that of molten magnesium in 1% 1,1,1,2-tetrafluoroethane/air atmospheres. The surface film formed on the molten magnesium is composed of MgF2, MgO and C, while the film formed on ZK60 melt mainly consists of MgF2, MgO, C and some ZrF4, and the film on ME20 mainly consists of MgF2, MgO, C and a small amount of CeF4. The good oxidation resistances of ZK60 and ME20 alloy melts may be caused by their major alloying elements Zr and Ce, respectively.
