| Porous ceramics are widely used in chemical,automotive,and construction fields.Porous alumina ceramic(Al2O3?3D?)reinforced aluminum matrix composite material(Al2O3?3D?/Al),also known as interpenetrating phase composites?IPC?,has an aluminum matrix and Al2O3?3D?reinforced phase,in space special microstructures that intersect each other.(Al2O3?3D?/Al)has the advantages of small mass,wear resistance,high specific modulus,high thermal conductivity,low thermal expansion coefficient,and high dimensional stability.It is used in high-precision ends such as weapons,communications,aerospace,and optical equipment field.In this thesis,batching-mixing-adjusting pH value-stirring process is used to prepare alumina slurry.Sketch up software is used to build a three-dimensional model.Simplify 3D software is used to layer the three-dimensional model.The Al2O3?3D?green body is made with alumina slurry by using 3D printing technology.The Al2O3?3D?green body is dried and sintered to obtain high strength Al2O3?3D?.When the aluminum alloy solution is 700?750?,the ultrasonic external field is introduced to use the cavitation effect.The acoustic wave effected to remove the attached gas and impurities on the Al2O3?3D?surface,improve the wettability of the aluminum alloy solution and Al2O3?3D?,The solution was completely filled into Al2O3?3D?,the aluminum alloy solution and Al2O3?3D?were recombined,and Al2O3?3D?/Al was successfully prepared.The thesis studies the influence of process parameters such as extrusion pressure,screw speed,layer thickness and printing speed on the forming quality of the green body,and studies the properties such as sintering temperature and the amount of kaolin added to the compressive strength and linear shrinkage of Al2O3?3D?.The impact of the structure of the Al2O3?3D?/Al structure and performance was analyzed using the finite element method,and the following conclusions were obtained:?1?The best 3D printing technology process parameters are print head diameter2.5mm,extrusion pressure 0.3MPa,layer thickness 1.4mm,and screw speed 600mm/min.The combined drying method of shade drying and heating drying can prevent the cracking of the green body.The optimal drying system is to put the green body at 25?and dry for 30 hours,and put it in a drying cabinet at 120?constant temperature drying for 8 hours.Kaolin plays a role in promoting sintering.The addition amount of kaolin is 20%,the sintering temperature is 1500?,and the Al2O3?3D?sintered body is prepared at 1500?for 4h to obtain the best comprehensive performance.?2?The microstructure of the Al2O3?3D?/Al interface is very stable.Al2O3?3D?ceramics can hinder the coarsening and growth of grains in the crystallization process of Al alloys.The grains of Al2O3?3D?/Al are fine.It is difficult for Al alloys to undergo phase transformation.The alloy composition is uniform and there is no segregation.?3?At a load of 20N,a tightly continuous,easily plastically deformed mechanical mixing layer is produced on the surface of the aluminum alloy substrate.The wear marks are shallow and clear,and the mechanical mixing layer is complete.Plastic deformation occurs locally in the mechanically mixed layer with a load of 40N and 60N,resulting in cracks,no obvious plowing,and the depth of the wear scar slightly increased.When the load is 80N,the mechanical mixed layer is torn and Al2O3?3D?/Al is obviously destroyed.?4?When the composite material corrodes Si particles as the cathode and the?-Al matrix as the anode,it constitutes a microbattery,so that the?-Al matrix near the Si particles is dissolved,and the product Al?OH?3 is formed to cover the surface of the composite material.?5?The stress transfer mechanism and the stress sharing mechanism are particularly important for Al2O3?3D?/Al with a brittle composition Al2O3?3D?,because the continuous elastic phase Al restricts the crack propagation of the brittle phase Al2O3?3D?and generates many The micro-cracks eventually improved the macroscopic failure of Al2O3?3D?/Al. |
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