Study On Direct Writing 3D Printing Technology Of Complex Configuration Laser Ceramics

Yttrium Aluminum Garnet(Y₃Al₅O₁₂,YAG)transparent ceramic material has excellent optical properties,high strength and hardness,good chemical and physical stability,which is an ideal solid state laser matrix material and has a wide range of applications in industry,national defense,basic scientific research and other fields.With the development of solid-state lasers,the preparation of gain media with complex shapes or multi-component structures is in urgent need of research.The traditional ceramic preparation process has the problems of complex process and high cost,and it is difficult to prepare ceramic devices with complex configuration.The size and shape of ceramic devices can be designed and controlled through3D printing technology.Among them,direct ink writing process based on ceramic slurry extrusion has significant advantages due to its simple manufacturing system and the ability to print high solids loading ceramic slurry.Based on the above background,we mainly adopt the direct ink writing process combined with UV-assisted curing and dual-nozzle printing.Through the exploration of slurry composition,direct writing process,light curing methods,debinding and sintering process,and design and optimization of a dual-nozzle printing system with nozzle switching and multi-component structure printing,the fabrication of YAG transparent ceramics,YAG ceramic tubes and multi-component structure（YAG/Yb:YAG/YAG）transparent ceramics was achieved,which opens up a new way for the fabrication of complex-shaped and multi-component structure transparent ceramics in solid state lasers.The main study contents are as follows:Firstly,for the photocurable YAG ceramic slurry that can be used for direct ink writing,the effects of the type and content of additive and the solids loading of the slurry on the rheological properties of the slurry were systematically studied,and the addition of 3 wt%Disperbyk-103 was determined as dispersant,which can prepare YAG ceramic slurries with a solids loading of up to 76 wt%.At the same time,the printability of the slurry was optimized by adding PVP.The final composition of the slurry was determined as YAG ceramic powder,commercial photosensitive resin,Disperbyk-103 and PVP.Secondly,by adjusting the printing parameters in direct ink writing,the relationship between printing layer height and line spacing was systematically studied,and the printing parameters of the sample were determined;by testing the relationship between the curing depth of the slurry and the surface irradiation energy,according to the Beer-Lambert law,the critical exposure energy of the slurry was obtained;Based on the value of the critical exposure energy of the slurry,two light curing methods（UV LED point light source and UV light curing box）that can cause the slurry to be cured were selected to for experiments respectively.Through experiments,it was found that the intensity of the light emitted by the UV LED point light source was different at each position,and it was impossible to prepare uniform transparent ceramics,while the YAG ceramics prepared after curing in the UV light curing box could achieve transparent;The debinding process of ceramic green body was formulated by thermogravimetric analysis,and the sintering process was determined as vacuum sintering at1750 ^oC;YAG transparent ceramic blocks were prepared by preparing YAG ceramic slurries with different solids loading（72 wt%,74 wt%and 76 wt%）.SEM microstructure observation results showed that there was no delamination in the internal structure of the ceramic green body.In addition,when the solids loading of the slurry was 76 wt%,the density of the ceramic green body was the highest,and the transmittance of the ceramic was the highest,and its transmittance at 1064 nm could reach 84%.Finally,the fabrication of YAG ceramic tube and multi-component（YAG/Yb:YAG/YAG）transparent ceramics was carried out on the basis of mastering the preparation process of YAG transparent ceramics based on UV-assisted curing combined with direct ink writing.YAG ceramic tubes were prepared by YAG ceramic slurries with different solids loading（72 wt%,74 wt%and 76 wt%）,and it was found that only 76 wt%of the YAG ceramic tube was intact and flawless;And then,on this basis,UV light was used for auxiliary curing in the molding process of the tubular sample,which increased the height of the sample,and successfully fabricated a YAG ceramic tube with a high aspect ratio.Through the design and manufacture of the dual-nozzle printing device,relevant accessories are assembled to realize the switching of the nozzles during the printing process;through the regulation of the printing program,the printing of multi-component structure（YAG/Yb:YAG/YAG）samples is realized,and finally obtained transparent ceramics.