Hydrothermal Preparation And Performance Study Of Ultrafine Calcium Silicate Phosphate Powder

Silicocarnotite is a new kind of bone repair and replacement material with good bioactivity and biocompatibility.In our previous work,pure silicocarnotite powder has been successfully synthesized through sol-gel method and solid phase method.Compared with hydroxyapatite?HA?,the CPS powder derived by sol-gel method has better bioactivity in vitro,which can significantly promote the proliferation of osteoblasts.However,it is difficult for CPS powder derived by sol-gel method to sintered into dense ceramic,which resulted in unfavorable mechanical properties and limitations of its application.The sintering properties of CPS prepared by solid-state method were improved but the bioactivity was relatively low compared with sol-gel method.Reducing particle size is an effective method to improve sintering property and biological activity of ceramic.The superfine powder can be directly prepared by hydrothermal method,and the powder prepared by hydrothermal reaction has the characteristics of high purity and good dispersion.In this study,the superfine silicocarnotite was prepared by hydrothermal method,the influence of reaction materials,reaction conditions,calcination temperature and calcination atmosphere on the preparation of CPS powder were investigated.Then,the synthesis mechanismand biological activity of the CPS powder and CPS ceramics were explored.The main results are as follows:?1?Well-crystallized and pure CPS was synthesized by hydrothermal method using Na₂SiO₃,Ca?H₂PO₄?₂ and Ca?OH?₂ as raw materials.The phase of the precursor was the pure apatite and the morphology of precursor powders were nanorods structure with diameters about 10 nm and length less than 100 nm.The diameters of CPS powders vary from 100 to 200 nm when the precursor was calcinedat 950?for3 h.?2?Studies have found that the calcination temperature was 900?for precursor transforming into CPS under nitrogen atmosphere,which show that nitrogen atmosphere could reduce the calcination temperature of CPS.?3?The hydrothermal synthesis mechanism of CPS was explored by analyzing the structure,composition and elements of CPS precursor.Transmission electron microscopy and energy spectrum analysis results showed that the precursor was apatite containing silicon.The results also support the idea that SiO₄^4-tetrahedra substitute PO₄^3-tetrahedra in the hydroxyapatite structure.?4?The silicocarnotite powder synthesized by hydrothermal method has good biological activity and can induce the formation of flower-like apatite in simulated body fluids.At the same sintering temperature,the porosity of CPS ceramics prepared by hydrothermal method is 4.6%.It shows that CPS ceramics prepared by hydrothermal method has better sintering property.