| Nano biomaterials become a most important branch in the field of materials and medicine, and they are recognized as a nuclear material in biomaterial in the 21th century. Natural bone is a composite material made of nano hydroxyapatite (Ca10(P04)6(OH)2. HAp) crystals and collagen fibers. Great attempts have been made to prepare the biomaterials with similar composition, structure and properties to the natural bone. Synthetical HAp materials show good biocompatibility and have the ability to form osteointegration. But due to its brittleness, pure HAp material is not suitable to be used for bone implant materials. The motivation of this work is to develop novel techniques to prepare riano HAp coating on titanium substrate, to acquire composite nano biomaterials with an excellent biocompatibility and bioactivity and mechanical properties.The HAp nano powder was synthesized by co-precipitation followed by hydrothermal treatment. Reaction temperature had great effect on the powder morphology. Through hydrothermal treatment the crystal growth of HAp in c-axes direction was enhanced, which was similar to the natural HAp crystals. Hydrothermal treatment also helped the growth of crystals with uniform size. Sol-gel method was also used to synthesize HAp powder. In this process, calcining was needed to complete the reaction, but high temperature caused the aggregation of powder and the powder size might be beyond nano scale.According to the flow and technical parameters of the synthesis of nano HAp powder, a reactor was designed to achieve a large-scale preparation of HAp under certain temperatureand pressure. It was shown that the HAp nano powder synthesized by this technique was of uniform structure and perfect crystalline. It is a safe, quick method to prepare large-scale HAp nano powder.The HAp/CTS and HAp/PDLLA nano composite powder were synthesized by co-precipitation and surface coating, respectively. The composite powder had uniform size and microstructure, which may avoid from some technical problem, such as, uneven microstructure, insufficient bonding between different phases, etc, by the traditional slip-casting method. This kind of nano HAp composite powder is suitable for preparing block materials or implant devices with various shapes in the clinical applications.Titanium and its alloy are used widely as bone implant materials due to their excellent mechanical properties and biocompatibility. The HAp coating on titanium surface can further improve the affinity between cells or biomolecules and implant surfaces, thus the bioactivity, biocompatibility and utility of biomaterials will be enhanced. In this work, the HAp nano coating on titanium surface was prepared in order to combine the bioproperties of HAp bioceramic and the excellent mechanical properties of titanium.A uniform HAp nano coating was formed on the titanium substrate by electrophorectic deposition (EPD). To overcome the shortage of traditional EPD process, such as relatively high sintering temperature, lower bonding strength than that of the coating formed by plasma spraying, etc., some technical improvements had been done. For the first time acetic anhydride was used as solvent to disperse HAp particles, which avoided adding acid solution into the suspension and the gas formed by the electroanalysis of water. The results indicated that using nano HAp powder to form a EPD coating on titanium substrate could decrease the sintering temperature as low as 800 "C, which was 200 "C lower than the temperature usedin general EPD coatings ( 1000). The coating was uniform, maintained nano structure and showed no cracks after sintering at 800 . After surface oxidation and chemical etch, a distribution of small pits acting as scaffold was formed on Ti surface. As a result, mechanical interlocking was formed between coating and substrate, which improved the bonding between coating and substrate. In the other hand, both Ti-OH groups formed by etching and the strong oxidation tendency of concentrated H2SO4 leaded to the formation of a thin TiO2 la...
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