Simulation And Experimental Study On Laser Selective Melting Process Of Alumina Ceramics

In recent years,ceramic materials have achieved widespread application in the fields of aerospace,biomaterial,automative,construction because of its advantages such as high temperature resistance,corrosion resisitance,wear resistance,high strength,high hardness and resistance to oxidation.However,the inherent characters of ceramic materials including high strength,high hardness and high brittleness brought challenges to the traditional processing technology,especially for complex shape ceramic pieces which usually rely on complex mould and have long production cycle and high manufacture costs.The above situation restricts the application and development of ceramic materials to a certain extent.Selective laser melting(SLM)technology with melt molding,no mold and the super-iority of application to a variety of materials provides a new idea for rapid manufacture of complicated ceramic components.The research of SLM technology of ceramic materials,not only enriches the technology means of ceramic manufacture,but also significantly shortens the production process of the ceramic specimens and improves the forming performance.This article mainly carries out the research on process simulation and experiments of alumina ceramic by SLM,based on the simulation analysis and process experiments,study the effect of key process parameters on the ceramic materials forming result by SLM.The main research work includes the following four points:(1)To study the finite element analysis theory of SLM and method of building simulation model:set the heat source function and boundary conditions;implement the material performance of nonlinear processing and phase change latent heat processing;establish the finite element simulation model of ceramic based on the theory of finite element analysis of temperature field and stress field.(2)To study the analysis method of temperature field from alumina ceramic SLM process simulation:through the study of the molten pool size,temperature gradient distribution,liquid phase time,heating rate,analyse the influence of the laser scanning speed,laser power,scanning strategies and preheating temperature on the temperature distribution.(3)To study the analysis method of stress field from alumina ceramic SLM process simulation:based on the indirect thermal mechanical coupling method,realize the building of alumina stress field model,explore the distribution of stress field in the forming process;analyse the influence of scanning strategy and preheating temperature on the stress field distribution.(4)To carry out the forming process experiments of alumina ceramic by SLM:study the difference of corresponding paving quality of different alumina powder state;take the analysis of influence of scanning speed,laser power and scanning strategy on the melting degree of alumina ceramic material;explore the influencing laws of forming results under preheating temperature;verify the validity of the simulation results.