Research On Laser Selective Melting And Forming Process Of Carbon Nanotubes/Aluminum Matrix Composites

Under the demand of light and high strength metal materials,carbon nanotubes(CNTs)has been developing continuously in research of reinforcement of aluminum matrix composites due to its high strength,small thermal expansion coefficient and low density.With the rapid development of aerospace and automobile industry,the trend of complexity and individuation of products is obvious.Traditional manufacturing methods are difficult to meet the manufacturing needs of complex shape models such as lattice and internal flow channel in aerospace field.Aluminum matrix composites urgently need to develop towards higher design and manufacturing freedom.Selective laser melting(SLM)technology uses laser heating and stacks model via melting powders layer by layer.SLM can directly form the lattice,internal flow channel and other complex parts according to the three-dimensional model.The design of model has a high degree of freedom and is less limited by the processing material.Research of CNTs/Al composite fabricated by SLM can not only enrich the manufacturing methods of CNTs/Al composites,but also provide the possibility for forming complex parts of CNTs/Al composites in aerospace,automobile and other fields.In this paper,the relevant works on the research of CNTs/Al composite fabricated by SLM were carried out,including the following points:CNTs/Al composite powders were prepared and their powder properties were compared.By SLM forming method,the qualities of CNTs/Al specimens using different composite powders prepared by various methods were compared.And the formation mechanism was analyzed.The preparation method of CNTs/Al composite powder suitable for SLM forming method was determined.CNTs/Al composite specimens using different CNTs content powder were prepared by SLM.Effects of CNTs contents on the dispersion state of CNTs,the density and microstructure of SLM forming specimen were studied.The state of CNTs in SLM specimens was observed by TEM,and the degree of reaction between CNTs and Al matrix was determined.SLM melting pools were formed by changing the scan speed.And the melting pools between CNTs/Al composite material and aluminum alloy were compared.The influence trend of process on the melting pool of CNTs/Al composite material and the cause of formation were analyzed and discussed.SLM single layers of CNTs/Al composite were formed by adjusting scan space,and effects of lap joint on the forming quality are analyzed with melting pool morphology.Forming quality of SLM aluminum matrix composites with different CNTs content was optimized by adjusting the scan space and scan speed,and the potential of high CNTs content composite materials was explored.The reasons were analyzed and the early inferences were verified.