Study On The Prorewties Of SLS Coated Sand By Silica Sol Coatings

With the rapid economic development,the competition in the industrial field is also fiercer and fiercer.However,the traditional foundry technology is far from meeting the development needs of modern industry.Therefore,the combination of selective laser sintering technology and traditional foundry technology is an inevitable development trend.Combining the SLS process with precision casting,the intermediate process for the casting of complex castings can be largely dispensed with,truly integrating the sand mold/core and moving in the direction of integration,facilitating the preparation of complex,thin-walled castings,while directly SLS sintered coated sand core?core?,for the large scale complex thin-walled integrated casting precision,moldless,high quality manufacturing to provide efficient technology approach.However,the low initial strength,poor surface quality and air permeability of the coated sand bring another new problem to the foundry technology.Only by breaking through these problems can the sustainable development of the foundry industry be promoted.In this paper,coated sand was chosen as the molding material for SLS sintering technology.The sintering process and post-treatment process of coated sand were studied to improve the initial properties of coated sand.The research status of selective laser sintering is summarized.The forming mechanism,forming material,forming equipment and forming process of SLS are introduced.The factors affecting the selective laser sintering process are analyzed.By analyzing the forming mechanism and forming process of coated sand,four factors of influencing factors,selecting scanning speed,laser power,thickness of powder coating and preheating temperature were determined.The orthogonal design of L₁₆?45?Tensile strength,flexural strength,and dimensional accuracy)to conduct range analysis,to determine the factors that affect the selective laser sintering of coated sand,and the extent of the impact of various factors.Determine the final coating sand sintering the best combination of process parameters.When the scanning speed is1800mm/s,the laser power is 35W,the powder thickness is 0.15mm and the preheating temperature is 60?,the forming quality of the coated sand sintered part is the best.Forming moldings using the optimum process results in a coated sand sintered part,but its performance is not sufficient for precision casting,and its performance needs to be improved.First pre-curing the molded parts,the pre-curing temperature and time were 180?and 2 hours,and then use different temperature silica sol coating on the molded parts.After which it is post-cured.The resulting parts were tested.Comparative study found that brushing silica sol coatings on the performance of coated sand has a certain role in improving,especially for its tensile strength,compressive strength and breathability significantly improved,providing a theoretical basis for the future production.