Research On The Preparation Of PLA/SIC Composites And 3D Printing Molding Process

3D printing rapid prototyping technology is becoming the mainstream technology of manufacturing as a highly flexible technology.PLA can be used as 3D printing consumables.However,its poor mechanical and thermal properties limit its application.On the other side,the SiC power has favorable mechanical and thermal properties while being compatible and dispersed well in PLA matrix.The PLA/SiC composites can meet the requirements of mechanical and thermal properties for 3D printing.This study prepared high-quality ?-SiC powders through combustion synthesis,produced PLA/SiC composites with different amount of SiC by blending modification,printed PLA/SiC composites by melt differential 3D printer and characterized the mechanical and thermal properties of the products.The main research contents and conclusions are as follows:1?Preparing high-quality nano ?-SiC powders by nitrogen assisted combustion synthesis method.The influence of reactants and synthesis process on the phase composition,particle size and morphology of products were discussed.Experimental results show that smaller particle size of Si powder and grinding and active treating the Si-C raw material can improve the reaction rate,but have no effect on product phase,particle size,etc.And exploring synthesis mechanism of SiC,namely the carbon black particles as the growth site,liquid and gaseous Si react with carbon black to form ?-SiC powders by diffusion mechanism.2?Utilizing SiC powders as filler and blending modifying PLA matrix by multiple blending and attaining the evenly dispersed SiC powders.Researching the influence of amount of ?-SiC on the type of crystal,crystallinity,rheological properties and thermal stability.Experimental results show that the addition of SiC promotes the heterogeneous nucleation of PLA and improves the crystallinity of the PLA,and increases the viscosity of composite materials and reduces the thermal stability of the composites within a certain range.Meanwhile,SiC powders treated with silane coupling agent in the PLA matrix get better dispersion.3?Using melt differential 3D printer printed PLA/SiC composites.Influences of the melting temperature,the screw rotation speed and the velocity of the three-dimensional platform on the quality of the product of 3D printing were investigated.Experiments show that when the melting temperature is in range of 210-220?,the screw rotation speed is about 0.7r/min and the average speed of the three-dimensional platform is about 2100mm/min,PLA/SiC composites can be printed steadily.When the filling amount of SiC powders is about 6-8wt%,the mechanical and thermal properties of 3D printing products are improved obviously.