Preparation And Properties Of Silicon Nitride Bioceramics Added With Zinc Oxide

Silicon nitride has good biocompatibility and mechanical properties,so it become a hot spot for more and more people to study,but its antibacterial property is low,which limits its use in many aspects of biomedical field.In order to prepare silicon nitride bioceramics with good antibacterial properties and excellent comprehensive properties,Si₃N₄ were prepared by the atmosphere pressure-sintering process,and tetra-needle ZnO whiskers,nano-sized ZnO and nano-sized ZnO/tetra-needle ZnO whiskers were added into Si₃N₄ respectively.The silicon nitride ceramics were prepared under the conditions of sintering temperature about 1600?,1700?,1700?,1750?,sintering pressure 4 MPa,and holding time 2 hours.The results showed that with the increase of the temperature,the flexural strength of the ceramics first increases and then decreases,and the same is true of the hardness and fracture toughness of ceramic materials.The increase of sintering temperature is beneficial to the densification of Si₃N₄ ceramics,and improves the mechanical properties of ceramic materials.Finally,it is determined that the appropriate sintering temperature is 1700?,whose density,shrinkage,and Vickers hardness,flexural strength and fracture toughness were3.21g/cm³?19.49%?612MPa?2060HVI and 6.68MPa·m^1/2.The silicon nitride ceramics added with zinc oxide towere prepared under the conditions of sintering temperature about 1700?,sintering pressure 4 MPa,and holding time 2hours.Considering the effect of different kinds of ZnO on the antibacterial properties,mechanical properties and microstructure of Si₃N₄ ceramics,among the most important study is antibacterial properties.The experimental results show that the antibacterial properties of silicon nitride bioceramics with nano-sized ZnO do not change obviously,and the comprehensive properties become weaker with the increase of nano-sized ZnO.The silicon nitride bioceramics with tetra-needle ZnO whiskers,and silicon nitride bioceramics with addition of nano-sized ZnO and tetra-needle ZnO whiskers which antimicrobial properties of the ceramic materials were improved significantly,and their comprehensive properties decreased slightly with the increase ofZnO.Finally,it was determined that the antibacterial effect of the composite ceramic materials was the best.The silicon nitride bioceramics with superior comprehensive properties are as follows:nanometer ZnO/tetra-needle ZnO whisker is added for 3 wt%,whose density,shrinkage,vickers hardness,bending strength and fracture toughness were 3.34g/cm³?19.29%?579MPa?2005HVI and 6.03MPa·m^1/2,respectively,the bacteriostasis rate for escherichia coli was 99.93%,and the bacteriostasis rate for staphylococcus aureus was 99.99%.