Study On Properties Of Lattice Zirconia Structures Prepared Via DLP Method

As a type of high performance ceramic,zirconia has high strength,high hardness and high toughness.However,the material itself is also a kind of difficult-to-cut material,the processing methods limit its development.Ceramic stereolithography process,as a supplement and upgrade to traditional ceramic processing methods,obtains uniform and dense porous structure after high temperature debinding and sintering.The zirconia lattice structure prepared by stereolithography has excellent properties and can be applied in medical and other fields.In the zirconia slurry,only 40vol% of powder is contained,which is far below that of injection moulding and other methods,so it is hard to use mature processing technology for reference directly.In this article,the digital light processing(DLP)of zirconia was discussed,including preparation of slurry,stereolithography process,debinding and sintering.The finite element method(FEM)was used to compare the mechanical tests of the sintered samples,which was a verification method of the lattice structure.The main research contents and main conclusions of the article were listed as follows:(1)The slurry system suitable for lattice structure ceramic body forming was studied through experiments.It was found that the ceramic slurry with a solid content of 40 vol%,a ceramic powder particle size of 300 nm and a dispersant content of 2 wt% had the optimal properties on the basis of ensuring fluidity.Meanwhile,a variety of lattice structure zirconia structures were printed on a self-developed DLP equipment by optimizing the forming parameters.(2)It was found that the ceramic green bodies without macroscopic defects could be obtained by combining vacuum debinding and atmospheric debinding.For the green bodies with lattice structure,the influence of sintering temperature curve on the properties of sintered parts was analyzed,and the sintering parameters were optimized through experiments.Finally,the lattice structure with complete grain boundary and uniform grain size without obvious defects was obtained,the Vickers hardness and the relative density reached 13.91 GPa and 95.1% respectively.(3)The shrinkage rates of porous lattice structure in all directions were obtained through multiple sets of experimental data,and the average shrinkage rates were used as correction factors to original models,where the factor for X and Y directions was 0.752 and 0.793 for Z direction.The lattice structures were reconstructed via industrial CT,the CT models and the corrected models had a high degree of overlap.So it was proposed to use the corrected model for finite element simulation instead of the CT model.(4)The static stress distribution,the dynamic compression process and the prediction of cracks were carried out on three types of lattice structures via finite element methods.Then,the bendingstrength of the zirconia material under the forming parameters and the compressive curves of three types of lattice structures were obtained through mechanical tests.It was found that the results of FEM were in good agreement with those obtained in actual tests,verifying the lattice structure strength had reached its theoretical strength.Based on the mechanical properties of lattice structure,the cell activity and cell adhesion of the structure were analyzed,the results showed that the lattice structure was non-toxic to cells and improved the contact area with tissues,indicating a good medical prospect.