Study On The Preparation And Tribological Properties Of Iron-Containing Hydroxyapatite

Hydroxyapatite（HA）is widely used in surgical orthopedics and hard tissue repair materials because of its excellent biocompatibility.However,pure HA ceramics have low strength,high brittleness,and are difficult to withstand large loads or impacts.At present,they are only applied to non-loaded small implants.As inorganic fillers,biological activity,opacity and polishability can effectively improve the mechanical properties of medical resins,but the easy agglomeration of nanoparticles limits its application.Modification of HA powder by ion doping is not only expected to prepare high-density HA ceramics,but also can be used as an inorganic filler and a modified composite resin filled with a small volume content,thereby expanding the application of HA.In this study,Fe-HA powder was prepared by Fe-doped through ultrasonic-assisted microwave hydrothermal synthesis.The effect of the pH value of the reaction slurry on the phase composition,crystal structure and micro-morphology of the synthesized Fe-HA powder was studied.Based on this,two different sizes of Fe-HA powders were used to prepare Fe-HA ceramics by pressureless sintering.The effect of precursor size on the microstructure and tribological properties of the ceramics was studied.At the same time,Fe-HA powder was used Bis-GMA/Fe-HA composite resin was prepared with inorganic fillers,and its tribological and biomedical properties were characterized.The main conclusions are as follows:（1）The powder prepared in this paper is nano-scale Fe-HA,and Fe element is doped in the HA lattice;among them,the pH of the reaction slurry will significantly affect the crystal structure of Fe-HA.When the pH of the reaction slurry is 6,the crystallinity of Fe-HA is low,and the grain diameter is about 30 nm,and some particles are agglomerated obviously.When the pH of the reaction slurry is 10,the Fe-HA crystals are complete and the grain size is large with a major diameter of about 120 nm,and present a typical one-dimensional rod-like structure.（2）Fe-HA powder prepared under acidic conditions is decomposed intoβ-TCP during sintering.Fe-HA powder prepared under alkaline conditions has high thermal stability and no decomposition reaction occurs during sintering.Therefore,the ceramics obtained from the sintering of Fe-HA powders prepared under acidic conditions areβ-TCP ceramics,and the Fe-HA powders prepared under alkaline conditions can be prepared by pressureless sintering to produce pure phase HA ceramics,and the HA grain size is small,uniform and dense.Ceramics have good mechanical properties and wear resistance.The microstructure and tribological properties of ceramics are closely related to the size and thermal stability of the precursor Fe-HA powder.（3）Adding an appropriate amount of Fe_1.5%-HA nano powder can improve the tribological properties,antibacterial properties and biological activity of the resin.When the powder content is 0.75 wt%,the hardness,flexural strength and abrasion resistance of the composite resin are significantly improved;when the powder content is 0.5 wt%,the composite resin has excellent biological activity.Bis-GMA/Fe-HA composite resin has good tribological properties,antibacterial properties,and biological activity,and is expected to be used in dental hard tissue repair.