Experimental Study And Performance Evaluation On Additive Manufacturing Of Tricalcium Silicate Ceramic Composite

With the continuous progress of modern medical level,it provides more possibilities for the cure of orthopedic diseases such as bone trauma,bone defect,bone tumor,and so on.The requirements for bone implants are also more stringent.The preparation of implants that meet the needs of the human body and match the performance of autologous bone has become one of the current research hotspots.Tricalcium silicate is a representative bioceramic material with good biocompatibility.At the same time,it can release calcium ion stably and combine with phosphate ion in body fluid to form hydroxyapatite deposited on the surface of ceramics,promoting cell proliferation and differentiation and new bone formation.However,its poor mechanical properties,unadjustable degradation rate and p H value of the surrounding environment after degradation,and difficult molding of high-precision complex structure limit its application in the field of artificial bone scaffold.In this paper,we use tricalcium silicate as the matrix material,combined with additive manufacturing technology,to improve its mechanical properties,in vitro degradation performance,hydrophilicity and printing parameters,which has important significance to meet the clinical application of bone repair,the requirements of biological scaffolds with different degradation rates,to adapt to different bone defect repair environment,and to match the speed of new bone regeneration significance.The specific research contents are as follows:1.The core-shell scaffolds of tricalcium silicate / sodium alginate were fabricated with a coaxial structure and slurry direct writing additive manufacturing technology,in which tricalcium silicate ceramic was used as the core material and sodium alginate solution as the shell material.When the mass fraction of sodium alginate solution is3wt%,the core-shell scaffolds can get the best hydrogel shell,the pore connectivity of the scaffolds,and the compressive strength is improved compared to the single calcium silicate tricalcium scaffold.In vitro degradation experiment results show that the degradation rate of core-shell scaffolds in vitro compared with the three calcium silicate ceramic scaffold and the p H value of the surrounding environment in vitro degradation of materials.At the same time,the water absorption and hydrophilicity of core-shell scaffolds are significantly improved compared with tricalcium silicate ceramic scaffolds,which is more conducive to blood adsorption into the scaffolds and promote cell adhesion.2.In view of the poor mechanical properties of tricalcium silicate,C3 S / 45S5 composite samples were prepared by combining 45S5 bioglass with tricalcium silicate bioceramics.The optimal sintering temperature of 45S5 bioglass was determined by thermal differential thermal analysis.In order to measure the effect of bioglass on the mechanical properties of ceramic samples,the compressive strength and bending strength of tricalcium silicate samples before and after sintering and C3 S / 45S5 bioglass samples were measured,and the optimal ratio of composite materials was obtained.The degradation rate of the composite sample added with bioglass decreased in vitro,which broadened the selection of bone scaffolds with different degradation rates in different bone repair environments.At the same time,the p H value of the surrounding environment increased,and the hydrophilicity of the composite sample also increased significantly.3.During the experiment,the printing parameters and post-processing of slurry direct writing additive manufacturing technology have a great influence on the forming quality of the sample.Therefore,the slurry flow rate in the forming process of C3 S /145S5 composite sample with the best proportion is analyzed and calculated,and then the moving speed of the substrate is determined,and its influence on the deposition line width and the porosity of the forming bracket is studied.Finally,the optimal printing parameters are obtained.Secondly,in order to reduce the sintering defects of the sample,the post-processing process of the sample is optimized.