| Calcium Polyphosphate is a kind of inorganic polymer and one of the calcium phosphate ceramics,has a controllable biodegradability,biocompatibility and adequate mechanical strength and nontoxicity,draws people's attention.But the preparation method of calcium polyphosphate powder mainly is melting-wire drawing-water quenching-drying-ball milling-sinter molding.This method is easily damage to the material,causing the purity that can not meet the medical level.At the same time,polymerization reaction and the temperature of crystalline transformation exist differences leading to failed to get the ideal material in the processing of preparation so that limiting the calcium polyphosphate(CPP)material in clinical research and application.Calcium silicate is a kind of biomaterial with high bone potential.It not only has bone conduction but also can induce the formation of new bone.In this paper,the calcium polyphosphate powders with different polymerization degree and crystalline were prepared by washing-drying-sintering method.And the gradient porous calcium polyphosphate ceramics was prepared by sintering method.CPP/CS composite bioceramics with different proportions were prepared by CPP,and the properties of CPP/CS composites were studied.The main research contents are as follows:(1)Different polymerization degree and crystal forms of calcium polyphosphate were prepared with using the method that is washing-drying-sintering.Gradient porous calcium polyphosphate was prepared using sintering.Sintering temperature,holding time and porosity were studied.The experimental results showed that the temperature range of the three different crystal forms of CPP was ?-CPP from 500?to 625?,?+?-CPP from 625? to 700? and ?-CPP from 700? to 950?.Sintering temperature became higher the compressive strength became higher.The polymerization degree was higher,the compressive strength increased firstly then decreased.The porosity was higher,the compressive strength became lower.When the porosity of the single-layer porous calcium polyphosphate ceramic was 65%,the compressive strength remains above 4MPa.Gradient porous structure not only can improve the mechanical properties of porous materials but also gurantee microhardness.When the gradient porous in 0/30/35 porosity is about 64%,the compressive strength is about 6 Mpa.The gradient porous CPP material that is similar to subchondral bone was prepared by optimizing the preparation process.(2)Using Tris buffer solution and SBF simulated humoral immersion method to test the bioactivity of CPP materials prepared with different crystal forms and polymerization degree.The results showed that the degradation rate of CPP materials in Tris or SBF was ?-CPP>?+?-CPP>?-CPP.Meanwhile,the polymerization degree of CPP is smaller,the degradation rate become faster.Moreover,after the calcium polyphosphate ceramic with different crystal forms have been soaked in SBF for 28 days,the bone-like apatite containing carbonate is generated.(3)Different proportions of CPP/CS composite bioceramics were prepared by die pressing and sintering method and bioactivity tests were conducted.The results showed that the compressive strength of CPP/CS composite bioceramics with different proportions changed significantly and the compressive strength of CPP/CS=50:50 increased to 2.3 times than pure CPP ceramics.After soaking for 28 days in Tris and SBF solution,it was found that the degradation rate of CPP/CS composite ceramics was faster than that pure CPP ceramics and the degradation rate was controlled from 0.21%to 20.89%.When the proportion of CS is 10%,the degradation rate is about 15 times than pure CPP ceramics.When the addition amount is 100%,the degradation rate is about 100 times than pure CPP ceramics.On the surface,bone-like apatite containing carbonate is produced,which indicates that the CPP/CS composite bioceramics have high compressive strength,biological activity controllable degradation and nontoxicity. |
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