Preparation And Mechanical Properties Of SiC_p/Al Lattice Structures

SiC_p/Al composite material has the characteristics of high modulus,low thermal expansion and high wear resistance of silicon carbide ceramics.And,it has low density,good corrosion resistance,good conductivity and other excellent properties of aluminum based materials.So,SiC_p/Al composite materials meet the requirements of the aerospace craft of lightweight high performance has been widely used in the areas of aerospace.And,SiC_p/Al lattice structure can further reduce the weight of the SiC_p/Al composites,realization of SiC_p/Al composite lightweight manufacturing,for the development of SiC_p/Al composite materials in aerospace,automotive and other fields of application has very important practical significance.However,SiC_p/Al composites have excellent wear resistance,which is very difficult for secondary processing,and SiC_p/Al lattice structures cannot be prepared by traditional processes.With the development of additive manufacturing technology,the preparation of components has got rid of the limitation of mold,making it possible to form the near net structure o f complex structure,especially the inner cavity structure.Selective laser sintering technology is one of additive manufacturing technology.In this paper,the near net forming of SiC_p/Al lattice structure was successfully realized by combining selective laser sintering technology with vacuum sintering technology.And,the mechanical properties of SiC_p/Al lattice were studied.The main research contents and conclusions are as follows:By selective laser sintering technology combined with vacuum sintering process was prepared by three different aluminum content(aluminum content is30%,40%,50%respectively)of SiC_p/Al composite materials.This paper studies the three different aluminum content of SiC_p/Al composite material of the density and porosity.The experimental results show that the SiC_p/Al specimen with the increase of the aluminium content,the porosity of the specimens is reduced,the aluminum content of 50%SiC_p/Al minimum opening porosity and porosity of the specimens,32.1%and 54.96%,respectively.The maximum density of SiC_p/Al specimen containing 50%aluminum was 1.32g/cm~3,while the minimum density of SiC_p/Al specimen containing 30%aluminum was 1.21g/cm~3.The mechanical properties of the three SiC_p/Al specimens with different aluminum contents were tested at three points.Brittle fracture occurred in all the three specimens.The bending strength and elastic modulus of SiC_p/Al specimens containing 50%aluminum content were the largest,17.61MPa and 4.09GPa,respectively.High porosity makes the mechanical properties of the SiC_p/Al specimen on the low side.In this paper,by cold isostatic pressing technology to reduce the porosity of the specimens to study the three kinds of aluminum content in low porosity three-point bending mechanical properties of the specimens.The experimental results show that with the reduction of porosity,the mechanical properties of three kinds of aluminum content in the specimen has the obvious enhancement,the aluminum content is 50%of the specimen bending strength maximum 96.24 MPa.Three kinds of SiC_p/Al lattice structures with different angles were prepared(the inclination angles of core and rod were 45°,60°and 75°,respectively).The relative density and compression properties of these three kinds of Si C _p/Al lattice structures with different angles were studied.And,the failure modes of three kinds of SiC_p/Al lattice structures with different angles were analyzed.With the increase of Angle,the relative density of SiC_p/Al lattice structure increases,and the maximum relative density of 75°SiC_p/Al lattice structure is 0.381.The compressive strength and elastic modulus of the 75°SiC_p/Al lattice structure are the largest,respectively 4.075MPa and 0.4191GPa.And,the compressive strength and elastic modulus of the 45°SiC_p/Al lattice structure are the smallest,respectively 0.657MPa and 0.0413GPa.The multi-scale SiC_p/Al lattice structure finite element model was established,and the SiC_p/Al lattice structure finite element model with high porosity was established.The mechanical response of SiC_p/Al lattice structure was studied.And,the equivalent elastic modulus and stress distribution of SiC_p/Al lattice structure at three different angles were simulated,which was in good agreement with the experimental results.The SiC_p/Al lattice structure model is used to predict the equivalent elastic modulus of the Si C _p/Al lattice structure with low porosity under compression load.