Digital Light Projection Preparation,Structure And Performance Optimization Of Additive Manufacturing Zirconia Ceramic Crown

Zirconia ceramic dental crowns possess high hardness,high wear resistance,tooth-like natural color,excellent aesthetic function,and long service life,and have been widely used in the repair of defective and missing teeth.Digital light projection（DLP）additive manufacturing can realize fabrication and customization of complex structures and high-precision advanced ceramic materials and products,with low material waste and high processing efficiency.This dissertation aims to explore the relationship between preparation process,microstructure and mechanical properties of zirconia ceramic dental crowns manufactured by DLP additive manufacturing.By optimizing the formula of zirconia-photosensitive resin slurry,DLP process and high temperature debinging and sintering process,ceramic dental crowns with excellent mechanical properties were prepared,The second phase of dental inert glass was incorporated to optimize the microstructure and mechanical properties of zirconia dental crowns.The optimization mechanism of microstructure and properties was revealed.Main conclusions are as follows:（1）The solid content has a significant effect on rheological properties of ceramic-resin slurry and the DLP molding quality of zirconia dental crowns,and the optimized solid content is 80wt%.The DLP process parameters have a significant impact on the molding accuracy,surface quality and density of zirconia crowns.The optimized exposure intensity,exposure time and slice thickness are 7s,16.5m W/cm² and 25μm,respectively.The debinding and sintering process affects the final shape,structural integrity and density of zirconia crowns.The optimal debinding temperature holding points are 300℃/120min and 550℃/120min,and the sintering temperature and holding time are 1600℃and 120min.（2）With increasing the slurry solid phase content and the sintering temperature,the relative density,mechanical properties and wear resistance of DLP fabricated zirconia ceramic crowns increased significantly.The higher the sintering temperature,results in the larger the grain size.The sample exhibit optimal comprehensive mechanical properties and wear resistance when the sintering temperature is in the range of 1500-1600℃and slurry solid phase content is 80wt%.Their relative density,compressive strength,Vickers hardness,fracture toughness and abrasive wear rate are 99.0-99.1%,677-698MPa,12.95-13.28GPa,6.3-6.8MPa·m^l/2 and 0.052-0.046mg/（min·mm²）,respectively.（3）The incorporation of dental inert glass secondary phase can improve the mechanical properties and microstructure of zirconia ceramic crowns.The sintering optimization effect at 1500℃is remarkable,adding 1wt%dental inert glass achieves better mechanical properties.1500℃sintered samples have relative density,Vickers hardness and fracture toughness of 99%,13.03GPa,6.33MPa·m^1/2,respectively,The abrasive wear rate is 0.03 mg/（min·mm²）,which indicates that the wear resistance is greatly improved.Dental inert glass is distributed at zirconia grain boundaries in the form of discontinuous phases.The fracture and material removal mechanisms of zirconia ceramic crowns are intergranular fracture and transgranular fracture.Incorporation of above 3wt%dental inert glass led to a continuous secondary phase that reduce properties of zirconia ceramic crowns.