Fabrication And Properties Of Porous Alumina Ceramics With Double Pores With Bionic Structure

In bone tissue engineering,artificial bone scaffold with spherical pore structure was conducive to the growth of cells,and spherical pore structure could effectively disperse the stress concentration and improve the mechanical properties of materials,so bone implant material with spherical pore structure had good application prospects.However,closed pore existed in these materials so that the connectivity of the materials was poor,which is not good for cells growth in depth and transporting nutrients and metabolites,thus affecting their biological properties.To solve this problem,this paper combined freeze-drying method and pore forming agent used microspheres to prepare porous Al₂O₃ ceramic with double pores,these materials included spherical pore and lamellar pore extending therethrough.The connectivity of porous ceramics was effectively improved.Designing bionics structure improved its mechanical properties.The experiment analyzed the impact of each parameter including microspheres content,solid content of the slurry,the structural design of sparse inside and dense outside on porosity,connectivity,mechanical properties.The experiment observed macroscopic,microscopic morphology of the sample,and conducted biological experiments.The following results were obtained:（1）When the microsphere content was 0.6g/ml,solid content of slurry was 30vol%,the complete morphology of porous Al₂O₃ ceramic with double pore including spherical pores and lamellar pore was prepared.The total porosity was 78.9% the opening porosity was 71.5%,the closed porosity was 7.4%,the connectivity of the sample was good,but the compressive strength of the sample was only 9.5MPa.（2）Using secondary freezing,Structural bionics double pores Al₂O₃ ceramic which was sparse inside and dense outside was prepared.When the solid content of the outer layer slurry was 45vol%,the solid content of the inner layer slurry was 30vol%,the microspheres content was 0.6g/ml,the inner radius was 4mm.The total porosity was 68.3%,the opening porosity was 58.9%,the compressive strength was 31.7MPa,providing high porosity and suitable compressive strength for the growth of cells.（3）Biological experiment showed that: when the inner radius was different,the absorption rate of cells increased with increasing the inner radius,and cell spreading morphology varied.Contrasting with single spherical pores,lamellar pore,samples with double pores was the highest on absorption rate of the cells,and cell spreading was good,extending pseudopodia of varying lengths,tightly contacting with the surface of the sample.