Research On 3D Printing Of Ceramic Particle Reinforced Aluminum Matrix Composites

Currently the studies on the additive manufacturing of ceramic particle reinforced AlMatrix composite are inadequate.It is necessary to conduct in-depth research on development of printing materials,optimization of printing process,characterization of micro-structures and enhancement of densification.In this project,high density ceramic particle reinforced aluminum matrix composites were successfully prepared via selective laser melting(SLM)using AlSi10Mg as matrix and light/heavy ceramic particles as reinforcement phase.The optimized microstructure and mechanical properties were characterized,and the strengthening mechanism of the reinforcement phase was studied.Moreover,the heat treatment post SLM was also studied,and the influence of heat treatment temperature on the microstructure and mechanical properties was investigated.The thesis includes the following parts:The SLM process parameters of the composites using light TiCN as reinforcement particles were studied.The results show that with optimized parameters including the laser power of 344 W,the scanning speed of 1800 mm/s and the scanning distance of 0.075 mm,the highest density of 97.32%can be obtained.The prepared samples have fine grains and no agglomeration of TiCN was observed.The TiCN,uniformly distributed in the Almatrix,can strengthen and improve the final properties of the composites.The hardness can reach 166±2 HV and the compressive strength can reach 608MPa.Based on the results of the casting WC(cast tungsten carbide,CC)and WC-20Co,suitable reinforcing particles were selected to optimize the material system.Better fabrication performance and micro-structures can be obtained when using casting WC.The process parameters of CC-AlSi10Mg composite were further optimized using experimental design.The results show that with the optimized parameters including the laser power of 180W,the scanning speed of 461 mm/s and the scanning distance of 0.07 mm,the density of98.2%can be obtained.The high melting point of cast WC enables good preservation in the molten pool,thus only small amount of cast WC was dissolved and diffused.Addition of WC particles improves the properties of the materials with the hardness of 233±11 HV and the compression resistance of 653 MPa,respectively.Also,the abrasion resistance is enhanced and the friction coefficient and abrasion rate values are only 0.16 and 1.8×10^-5mm³ n^-1m^-1,respectively.The effects of different heat treatment post SLM on the phase,microstructure and mechanical properties of aluminum matrix composites were studied.The results show that both the hardness and the compression resistance of the two materials decrease when increasing the annealing temperature.The plasticity of the two materials increase when applying T6 heat treatment.