Study On The Process And Properties Of Copper Matrix Composites By Selective Laser Sintering

Additive Manufacturing Technology was introduced in the 1980s,and it is a new manufacturing method based on material layer stacking method.It is a set of computergraphics processing,digital information control,laser technology,mechanical and electrical technology,materials science and technology,and many other high-tech advantages of manufacturing methods.As an important branch of Additive Manufacturing Technology,Selective laser sintering is concerned owing to its high utilization of materials and wide range of forming materials.According to the current research status and characteristics of selective laser sintering,the indepth analysis of the formability of raw materials of SLS mixed powder system is analyzed.In this paper,a Cu-SnBi58-rosin mixed powder system was designed and prepared,and the mechanism of sintering formation of this mixed powder system was analyzed in depth.The influence of two major factors of powder material characteristics and process parameters on the formability of the sintered part was studied,and the post-treatment process such as infiltration of the sintered part was studied.The effects of chemical characteristics,physical characteristics such as powder particle morphology and particle size on laser forming properties were analyzed.The effect of parameters such as laser power,scanning speed,powder coating thickness and scanning pitch on the density and mechanical properties of the sintered part was analyzed experimentally.The mechanism of the action of the impregnation liquid and the matrix during the infiltration process was analyzed,and the mechanism of the improvement of the mechanical properties of the parts was analyzed.Experimental studies show that the SLS forming process of Cu-based composites is a liquid-phase sintering mechanism:the Cu particles do not melt during the laser sintering and act as the framework metal;the SnBi58 alloy powder is melted by heat to form a liquid phase,wet,coated and adhered Solid phase particles,rosin mainly play the role of deoxidizer.Experimental studies have shown that the sphericity is good and the mixed powders with coarse and fine particles have better forming properties.The optimized powder ratios are:Cu:SnBi58:rosin=70:29.95:0.05.The laser power is positively related to the formability of the sintered part.Within a certain range,the performance of various aspects of the sintered part increases as the laser power increases.Scanning speed,powder coating thickness,and scanning pitch are negatively related to the formability of the sintered part.Within a certain range,the performance of various aspects of the sintered part increases with decreasing parameters.Through comprehensive regulation of energy density?ie,various process parameters?,sintered parts with good performance are obtained.After many sintering experiments,the optimized process parameters were optimized:laser power P=30W,scanning speed V=50¹00mm/s,paving powder thickness?=0.15mm,scan spacing L=0.15mm.The experimental study shows that the sintered parts are infiltrated with SnBi58alloy.Under the action of gravity and surface tension,the alloy liquid can infiltrate and fill these voids gradually,and alloying reaction occurs with the Cu-based powder.Sn element to Cu powder matrix in the full diffusion of Cu-rich conditions in the following complete reaction 6Cu+5Sn?Cu₆Sn₅?Cu₆Sn₅+9Cu?5Cu₃Sn,that Cu almost completely react with Sn to form a Cu₃Sn stable phase.Metal Bi does not participate in the reaction,but filled in the gap between the Cu powder,play the role of connecting Cu powder.