Study On Nano-hydroxyapatite And Its Bio-composites

Hydroxyapatite(HA) is one of most important inorganic components. In recent20 years, the study of biomaterials like natural bone is active. HA was believed to bethe best materials for bone structure. In order to get a new material which should hasboth good mechanical properties and bioactivity, new methods of preparing HAcomposites are raised. At first, HA powders and needle-like HA crystals were madeby a wet precipitation method. The resulting powders were used to prepaere two kindsof new composites—titanium fiber reinforced HA composite and porous HA prepregreinforced PMMA composite.In this paper, microstructure was observed by SEM and TEM, phase structurewas analysed by XRD and FTIR, and element content was analysed by EDS.Influence of HA sintering was studed and interface reaction between Ti and HA wasalso inverstigated. New composite preparation approaches were discussed.HA powders were prepared by wet precipitation method in this paper. The effectof solution concentration, temperature, pH value and aging time affected thegranularity and morphology of HA powders. Bioceramic powders consisting of HAand Ca3(PO4)2 were received by calcining wet precipitated powders. Increasing pHvalue or prolonging ageing time was found to increase HA content in the resultedpowder mixture.A new titanium fiber reinforced hydroxyapatite biocomposite was fabricated byvacuum sintering and slip casting. Long fibers of titanium were incorporated in amatrix of hydroxyapatite to toughen the hydroxyapatite. The interface wasinvestigated for microstructure and chemical composition. Slip casting avoided theinitial stress and the interface reaction of titanium and hydroxyapatite eliminated thedifference of thermal expansion. Diffusion of titanium promoted the decomposition ofhydroxyapatite and formation of transition area. Titanium and its oxid reacted withhydroxyapatite, created products such as calcium titanate, and so on. The productsimproved interface combination and matching, which can be used as transition areafor metal-ceramic composites. The interface reaction layer can be controlled bytitanium surface treatment.HA porous prepreg reinforced PMMA composites were prepared byimpregnation method and in situ mass polymerization. Viscosity of PMMAprepolymer and temperature of in situ mass polymerization were critical to thepreparation of composites.