Preparation And Damping Properties Of 316L Stainless Steel Hollow Spheres/Aluminum Matrix Composite

Metal hollow sphere composite is a new kind of composite material composed of metal hollow sphere and different kinds of matrix.It has been widely paid attention in the field of functional materials with low density,high specific strength,high energy absorption,high damping and so on.Based on the 316 l stainless steel powder,red porcelain clay powder,flour,and Ni Ti alloy A356 aluminum alloy plate as the raw material,through the powder metallurgy method,pressure casting metal hollow balls and its compound materials were prepared,study different template technology and sintering temperature on the metal hollow ball yield,microstructure and mechanical properties,the influence of different preparation technology of hollow metal ball composite microstructure,mechanical properties and damping performance,the influence of the preparation of metal hollow balls and its composites.The results show that:（1）With the decrease of template-removal heating rate,the yield of hollow metal pellets increased continuously,and the yield of hollow metal pellets increased from 0%of the heating rate at 10℃per minute to 68.5%of the heating rate at 1℃per minute.With the increase of sintering temperature,the porosity of the hollow metal balls decreases.When the sintering temperature reaches 1300℃,the hollow metal balls melt and the porosity reaches the minimum.With the increase of sintering temperature,the compressive strength increases.When the sintering temperature is 1200℃,the comprehensive performance of the hollow metal ball is the best.（2）The casting temperature of 720℃and 750℃was adopted for the exploration process of metal hollow ball composites,and the holding time was 30 minutes.In this process,the metal hollow balls and intense reaction occurs,Ni Ti alloy plate and matrix under the macro metal hollow balls and most of Ni Ti alloy plate disappear,microscopic,with increasing of casting temperature,the reaction of the metal hollow balls and aluminum substrate layer increases,Ni Ti alloy plate element of Ni and Ti elements are completely with aluminum reaction between nickel aluminum and titanium metal compounds.（3）The optimized technology of metal hollow ball composite was selected and cast at720℃,and the effects of holding time of 10,15,20 and 25 minutes on the composite were studied.The hollow metal ball and Ni Ti alloy plate can be observed macroscopically in this process.With the extension of holding time,the reaction layer between the hollow metal ball and the matrix increases gradually.When the holding time reaches 20 minutes,the Ni Ti alloy plate reacts with the matrix to form a protruding,and the Ni rich zone and the Ti-rich zone are formed on the protruding zone,respectively.Based on the results of first principles and point analysis,Fe₂Al₅ is generated by the reaction between the hollow metal ball and the matrix,and the Ni rich region is Ni Al₃ and Ti Al₃ by the reaction between the Ni Ti alloy plate and the matrix.（4）The quasi-static compression test of metal hollow ball composites with different holding time under the optimized process shows that the stress-strain curve of metal hollow ball composites presents three stages as the same as that of other foam materials:yield stage,platform stage and densification stage.With the extension of holding time,the compressive strength of the metal hollow ball composite increases.When holding time is 20 minutes,the compressive strength reaches the highest 157 MPa.Under different heat preservation time on the metal hollow ball composite damping performance test,get four different at room temperature holding time of the loss factor of the composite material,with the extension of heat preservation time,the loss factor are increased,when the time of heat preservation is 20 minutes,metal hollow balls the loss factor of the composite reached its highest 0.1767.