The Preparation And Characterization Of CNTs/FHA Biocomposite Ceramics

In recent years,with the rapid development of biological science,the application of inorganic biological materials has been widely concerned.Among these inorganic materials,hydroxyapatite?HA?bioceramic materials in the clinical application have made a great breakthrough.HA as an inorganic biological material,it has a very similar organizational structure and chemical composition with teeth and bones.After years of research,it has been found that HA has a good biocompatibility and bioactivity.After implanting,the tissue cells do not show a strong rejection,and HA can form a strong chemical combination with bone tissue.In this case,the HA bioceramic provides a support for new bone tissue,so it is a suitable alternative to bone tissue.However,on the one hand,its mechanical properties are low,which limits its application in the bearing position.On the other hand,the dissolution rate of HA is high in body fluids,which will lead to implant failure.Motivated by the findings mentioned above,we fabricate carbon nanotubes/fluorohydroxyapatite?CNTs/FHA?biocomposite ceramics.The introduction of CNTs is helpful to improve the mechanical properties of HA ceramics.The incorporation of fluoride can improve its corrosion resistance and mechanical properties.In this work,MWNTs are modified by acid oxidation.The Raman spectrum shows that the modified MWNTs still have a relatively complete structure,and its R value increases,which indicats that the CNT structure defects increase.From the X-ray photoelectron spectroscopy?XPS?of CNTs,three kinds of functional groups:?hydroxyl,carboxyl and C-O-C?can be observed.The TEM image and dispersibility test show that the modified MWNTs have good dispersibilities.The composite powders of HA?FHA and X wt.%MWNTs/FHA?X=0.5?1?2?5?are prepared by the in-situ chemical synthesis method.Then the bioceramics are consolidated by spark plasma sintering?SPS?.The Raman spectrum indicates that the MWNTs do not decompose after SPS.The X-ray diffraction?XRD?spectrum shows that the main phase of the bioceramics is apatite,but a small amount of?-Ca₃?PO₄?₂ is formed.In addition,MWNTs increase the cell volume of FHA.The relative density test indicates that MWNTs reduce the relative density of biocomposite ceramics.The hardness of biocomposite ceramics is the largest when the content of MWNTs is 1wt.%,compared with HA ceramics increased by 28%.The fracture toughness has no obvious change when the content of MWNTs is between 0.5 and 5wt.%,compared with HA ceramics increased by 35%.In vitro biological activity results show that the X wt.%MWNTs/FHA biocomposite ceramics have good bioactivity.The composite powders of 1wt.%MWNTs/F_xHA?x=0?0.4?0.8?1.4?1.8?are prepared by the in-situ chemical synthesis method.Then the biocomposite ceramics are prepared by SPS.The Raman spectrum indicates that the MWNTs do not decompose after SPS.The XPS spectrum shows that F^-has successfully replaced OH^-.The XRD result indicates that the main phase of the biocomposite ceramics is apatite.The lattice spacing of the?300?crystal plane decreases with the increase of F content,and the true density of the biocomposite ceramics increases with the increase of F content.The relative density test indicates that the relative density of the biocomposite ceramics is close to 100%when the content of F is x=1.4 and 1.8.The solubility test shows that the introduction of F^-improves the corrosion resistance of the biocomposite ceramics The hardness of biocomposite ceramics is the largest when the content of F is x=1.8,compared with HA ceramics increased by 40%.The fracture toughness of biocomposite ceramics is the largest when the content of F is x=0.4,compared with HA ceramics increased by 70%.In vitro biological activity results show that the biocomposite ceramics has the best bioactivity when the F is x=0.8.