The Preparation And Study Of Nano-Hydroxyapatite Biomaterials

Nano biomaterial is an important component and development of the material and medicine field, nano materials will become the core of biomedical materials in 21st century. Nano biomaterial is an important component and development of the material and medicine field, nano materials will become the core of biomedical materials in 21st century. Natural bone is a composite materials which is made up of hydroxyapatite (Ca10(PO4)6(OH)2, HAP) crystals and collagen. To make the nano-biomaterial which is close to natural bone is the goal that people keep working on it. Synthetic hydroxyapatite material has good compatibility with human tissue, and it can make bone combination with bone formation, but because of the brittleness of the material, it is not fit for making the strong load part of the body. The purpose of this paper is to study the preparation methods of nano-hydroxyapatite's layer and to combine with different materials, according to obtain the nano-biomaterial with superior mechanical properties and biological properties. The research results of this paper are as follows:1.To synthesis hydroxyapatite by exploiting chemical precipitation, the samples were characterized by using XRD and SEM, the result shows that: Precipitation time has much effect on the crystallinity of HAP. When the precipitation time is 4 hours, the product is very tiny crystallite, the size of the crystallite is about 15nm, when the precipitation time is 24 hours, HAP crystallite is complete, the size is larger, and it is around 40nm. When H3PO4 dropped too slowly, the HAP grain was prone to be agglomeration, when it dropped too fast, the grain became too coarse and had more crystal defects. The experiment shows that when the speed of dropping was 2ml/min, we can obtain tiny complete nano-HAP that could distribute uniformly. With the increase of sintering temperature, the size of HAP grain increased gradually, and the grain was more complete , but when the temperature was too high (900℃), the grain appeared very serious agglomeration. In this experiment the optimal heat treatment temperature was 700℃, from that the HAP crystal was integrated, could distribute uniformly and it also had less particle agglomeration. The PH of solution changed a little at the preliminary stage of reaction, and later decreased sharply, it showed that the main stage of HAP nuclei's formation is in the later period.2.By using the hydrothermal method, with diammonium phosphate and calcium nitrate as the precursor to make hydroxyapatite nanorods ,the crystal was characterized by using XRD, SEM, TEM, HRTEM。The results showed that: PH is the important factor which could effect to make HAP nanorods by using hydrothermal, the increase of PH could inhibit the growth of crystal's c-axis,When PH = 10, we got the pure HAP crystal that grew completely , with the increase of hydrothermal time, HAP grew bigger gradually, when t = 12 ,we got HAP nanorods which has better form. However, with the reaction time got longer, the direction of HAP grain's c-axis grew slowly, a-axis and b-axis continued growing, from that we can obtain spherical HAP nanoparticles. Hydrothermal Synthesis HAP is a response of gradual process, with lower temperatures will produce a number of intermediate products, so we need to work on it with higher temperatures to get higher purity and more complete HAP powder , so the study showed that the powder we got at 150℃is the best. Increasing the filling degree of reactor, it is good for increasing the pressure in the reaction ,and so that we can also increase the rate of producing HAP crystals in hydrothermal reaction。According to anion coordination polyhedron growth unit theoretical model, to apportion the ion during the process that HAP crystal is growing, to explain the growth rate of crystal face in different conditions. Finally we got the optimal reaction of the Hydrothermal to produce HAP grains :hydrothermal solution PH=10, response to 12h, temperature of water is 150℃, the filling degree of reactor is 80%, it is the best condition to admix HAP nanorods in this experiment. The HAP crystals which produced in this condition are rod-like grain, and they could distribute uniformly ,synthesis of HAP under this condition are rod-like grain shape and distribution, high crystallinity, grain length is less than 100nm, the width is less than 50nm.3.In addition, complexing HAP and carbon nanotubes didn't work well, but this method is feasible in theory, it still needs further researchHAP/TiO2 composite material was prepared by two different composites, it produced eutectic phase between HAP and TiO2, it confirmed the possibility of using these two methods to make HAP/TiO2 composite material, and it also provided the new methods to complex HAP and titanium, we hope to obtain better bone substitute materials by further research.