The Influence Mechanism Of Reaction Temperature On The Preparation Of Hydroxyapatite Whisker By The Homogeneous Precipitation

Hydroxyapatite?hydroxyapatite,HAP?is a kind of weak alkaline bona,belongs to the biological activity material,it is also one of the important inorganic qualitative compositions of biological bone.Because of its good biological properties,HAP is widely used in medical fields,especially in orthopedics,It has good bioactivity and biocompatibility.It can also make close combination with bone formation,guide the growth of bone.It is a kind of comprehensive performance of biomedical materials.In this experiment,using Ca?NO₃?2·4H₂O as the calcium source,?NH₄?₂HPO₄ as a source of phosphorus,carbamide as precipitant,using homogeneous precipitation method in the preparation of hydroxyapatite whisker,the whisker was researched by a systemly kinds of researches,by the use of characterization methods such as Fourier infrared spectroscopy?FT-IR?,scanning electron microscope?SEM?and X-ray diffraction?XRD?The research are based on different products under the condition of reaction time and temperature were studied.At the same time the growth process of HAP whisker and growth mechanism under different reaction conditions were discussed.The results show that:?1?Under the condition of low temperature and low pressure,single phase was synthesized by homogeneous precipitation method.It is in a good appearance as pure hydroxyapatite whisker,the average length of the whisker is about 50 ?m,the average width of them is about 2 3 ?m,the average length to diameter ratio is between about 20 30.?2?Different reaction time.At the beginning of the reaction will be?OCP?composition among eight calcium phosphate and calcium hydrogen phosphate?DCPA?generated,as the reaction progresses,the formation of HAP is increased gradually,gradually reducing the OCP and DCPA,eventually generate into relatively pure HAP crystal phase.According to the characteristics of the HAP structure and morphology characteristics of different reaction time,combining with several kinds of crystal growth mechanism modelto explore the growth mechanism,found that in different periods,the growth mechanism of HAP whisker is different,its growth trend continuely gose along with the c axis.At the beginning of the reaction,the growth mechanise is mainly composed of two-dimensional nucleation growth.With the increasing of the nucleation rate and growth rate,it gradually transformed into continuous growth in the late reaction,eventually forms in a thin sheet of HAP.?3?Different reaction time.Between 70? to 75?,it can't generate the pure HAP phase,between 80? to 85?,the crystal phases are mixed by OCP and DCPA phase,they are gradually transforming into HAP pure phase,when the reaction temperature is 95?,in a relatively short period of time,we can get pure phase of HAP.When the reaction temperature is between 70? to 85?,the morphology of HAP whisker presented a quarter section of cellular long beam.The growth of HAP whisker is influenced by concentration gradient,temperature gradient and the change of interfacial energy,the growth mechanism is cellular interface.And between 90? to 95?,the reactive ions in the solution are in saturated states,forming a homogeneous system,so that we can get complete laminar HAP whisker with smooth surface..