Preparation And Properties Of β-SiAlON-Si₃N₄ Composite Bioceramics

In modern medicine,synthetic bone replacement materials are increasingly used to treat orthopedic diseases.In order to meet the needs of bone replacement materials,metal,inorganic nonmetal and polymer materials have been used in the research and preparation of bone replacement materials.Studies have shown that these materials have their own advantages and disadvantages in physical,chemical and biological properties.β-Si₃N₄ ceramics not only has excellent mechanical properties,but also has biocompatibility and osteoinductive activity.It can show good affinity with huaman tissues such as bone tissue,and has excellent imaging performance,so it can be used as bone replacement material.However,β-Si₃N₄ ceramics also has the disadvantages of difficult sintering and high preparation cost,which limit its application in bone replacement materials.β-SiAlON,as a solid solution ofβ-Si₃N₄,has a similar lattice structure toβ-Si₃N₄ and similar mechanical properties,butβ-SiAlON can achieve good sintering at relatively low temperature.In this study,β-SiAlON was added intoβ-Si₃N₄to prepareβ-SiAlON-Si₃N₄ composite bioceramics（SNL ceramics）.The effects of sintering temperature,β-SiAlON content and Z value,and addition amount of sintering additives on the physical and chemical properties of SNL ceramics were studied,and their biological properties were evaluated.The experimental results are summarized as follows:（1）The experimental results of different sintering temperatures show that the increase of sintering temperature is beneficial to the crystal transformation fromα-Si₃N₄ toβ-Si₃N₄.When the sintering temperature is 1600℃,the main crystal phase of the ceramic isβ-Si₃N₄,and the grains are rod-shaped and tightly connected,and have good physical properties.By changing the content ofβ-SiAlON and Z value,the porosity,bulk density and compressive strength of samples can be controlled,and the porosity can be close to human cortical bone,and the compressive strength of bone replacement materials can be met.The additive yttrium oxide can obviously promote the crystal transformation of silicon nitride.When the addition amount is about 4 wt%,the physical properties of SNL ceramics reach the best.（2）The experimental results of the surface chargeability of the material show that after the addition ofβ-SiAlON,the surface chemical properties of SNL ceramics are more active,and OH^-is bound to the surface of the material,making the particles negatively charged.The change of Z value ofβ-SiAlON has little effect on the charge of the material surface.The results of ion release experiments show that Si,Al and Y elements in SNL ceramics can be released and change the p H of water.The results of chemical erosion experiments showed that the surface morphology of SNL ceramics did not change significantly after being soaked in culture medium for 28 days,indicating that the chemical properties of SNL ceramics were stable in culture medium.（3）The results of cell culture experiments show that osteoblast precursor cells MC3T3-E1 grow,proliferate and adhere well on the surface of the material,indicating that the material is non-toxic and has good biocompatibility.With the increase of culture time,the expression of osteogenic differentiation marker genes increased,and the number of mineralized nodules increased,indicating that SNL ceramics can effectively promote osteogenic differentiation and bone formation.In addition,increasing the Z-value ofβ-SiAlON has no adverse effect on the biocompatibility of SNL ceramics and can further promote the differentiation of osteoblasts.By studying the physical properties of SNL ceramics,composite ceramics with good physical,chemical and biological properties were prepared,which provided a good experimental and theoretical basis for the development of new bone replacement materials.