Study On Additive Manufacturing Process And High Temperature Evolution Behavior Of SiOC Precursor-derived Ceramic

In recent years,ceramic additive manufacturing technology has gradually entered the public field of vision,developed rapidly,and has been widely used in various fields.Ceramic materials have many advantages,such as high temperature resistance,chemical corrosion resistance,excellent thermal insulation performance and high temperature stability.They are widely used in chemical industry,mechanical electronics,aerospace,medical and other fields.The traditional ceramic preparation method,after decades of technological innovation,although the process has been improved,but the whole process of preparation cycle is long,the ceramic sintering temperature is high,the machinability is poor,it is difficult to manufacture high-precision,complex geometric ceramic components,and additive manufacturing technology provides a new way for the advanced ceramic component structure function integration.In this paper,the preparation and process optimization of SiOC precursor-derived ceramics are studied as follows:The additive manufacturing process of a new type of precursor-derived ceramic material is explored,which belongs to the additive manufacturing technology field of ceramic materials.The precursor-derived solution was prepared with high silicon content bifunctional acrylate silicone resin AgisynTM250,crosslinker trimethylolpropane triacrylate TMPTA,solution diluent γ-trimethoxysilane KH-570,mixed photoinitiator and dye Sudan Ⅲ as main raw materials,When the ratio of agisyntm250:TMPTA:KH-570 is 1:5:3,2.2 wt%mixed photoinducer and 0.1 wt%Sudan Ⅲ dye are added,and the UV curing technology is adopted,which has good molding effect and can print 3D model with certain spatial structure.In Ar atmosphere,the precursor ceramic materials with integrated structure and function are prepared by high temperature pyrolysis under a specific temperature program.The high temperature evolution behavior of the precursor-derived polymer in the pyrolysis process was studied.The thermokinetic analysis was carried out to determine the thermal decomposition reaction mechanism and solve the rate equation.In the process of pyrolysis of precursor polymer into SiOC precursor ceramic composites,at 300～550 ℃,the mass loss and volume shrinkage of the precursor polymer are obvious,and the pyrolysis and rearrangement of chemical bonds release C2H4,CO2 and other small molecular gases,realizing the transformation of organic polymer into inorganic ceramic materials.The pyrolysis products were characterized by TGA/DSC,FT-IR,XRD,Raman spectra,SEM/EDS,and the SiOC/SiC precursor ceramic composites with excellent high temperature resistance were prepared.The optimization of pyrolysis process parameters and microstructure of SiOC precursor ceramics was studied.In the process of pyrolysis and vitrification,the volume of precursor polymer shrinks,a large number of pores appear in the material,the surface quality is poor,and a large number of cracks exist.The results show that:when the post-treatment time of SiOC precursor polymer is 3 h and the pyrolysis temperature is 4℃/min in argon atmosphere,the surface cracks and pores of SiOC precursor ceramics can be reduced;3 wt%nano SiC powder inert filler can fill the cracks and pores due to the escape of small molecule gas,reduce the volume shrinkage by 73.47%,increase the ceramic yield by 26.42%,and increase the volume density by 1.722g/cm3,taking into account the maximum efficiency and yield.