Doping Modification Of Ag/AnO₂ Powder And Simulation Of Hot Extrusion Process

As the most promising electric contact materials now,Ag/SnO₂ had achieved batch production in some developed countries.Our country started late on Ag/SnO₂ materials,there are some problems in preparation process such as poor wettability between SnO₂ and Ag,difficulty for processing molding need to solve.In order to accelerate Ag/SnO₂ material's localization,it is extremely important meaning.The paper mainly does some prophase works of synthesis of Ni doped SnO₂ powder and analyzed the related parameters of Ag/SnO₂ material molding process by Deform.Obtained the parameters of synthesis of Ni doped SnO₂ powder and the theory optimum parameters of molding processing,providing data support for the batch production of Ag/SnO₂ material.Ni-doped SnO₂ Nano-powder were prepared by hydrothermal method.The effects of Ni doping content,pH value,hydrothermal temperature on the phase,grain size and surface morphology of the nano-powder are studied.Meanwhile,the structure and morphology are characterized by adopting X-ray Diffraction?XRD?,Scanning Electron Microscopy?SEM?and Energy Dispersive Spectrometer?EDS?.The results show that under the condition of molar ratio of Ni2+ and Sn4+ is 1:5 and hydrothermal temperature at 160? Ni-doped SnO₂ Nano-powder with an average size of 200 nm was obtained.The agglomeration of powder aggravates with the increase of doping content.Characteristic peak of SnO₂ widens which hinders the SnO₂ crystallization process when the molar ratio of Ni2+ and Sn4+ rises from 1:10 to 3:10.According to actual process parameters to build Ag/SnO₂ electrical contact material hot extrusion finite element model by Deform simulation software,and simulated the processing of extruding the Ag/SnO₂ material blank into wire.The results of simulation for different hot extrusion parameters such as temperature,load-stroke curve,stress and strain of die and blank are obtained.According stress concentration of die in processing of extruding,optimized the structure of die by building the model of die's wear.The results of simulation shows that wire temperature close to blank's initial temperature and the stress and strain of die relatively small when extruding in 8mm/s.Obtained optimization parameters by analyzing the model of die's wear,stress concentration of die be improved when the angle of chamfer radius at 0.75mm.It is beneficial to extrusion process at 550? of die temperature,and initial hardness design between 56HRC and 60HRC is reasonable.