NCS System Glass-ceramics And Its Bone Ashes Doping

Wollastonite glass-ceramics have good mechanical properties and chemical stability,but low biological activity.Hydroxyapatite has good biocompatibility and biological activity,but chemically synthesized hydroxyapatite has a single component,lacks the organic ions in human bone apatite,hardness and strength are lower than bone apatite,so the application in biological materials is restricted.Apatite-wollastonite glass-ceramics,containing both apatite and wollastonite crystal phases,has good mechanical properties and biological activity.It is a good biological material for bone tissue engineering.Therefore,in order to obtain a kind of wollastonite-hydroxyapatite biphasic glass ceramics with good’sintering performance,high strength and good biocompatibility,this project prepares hydroxyapatite from animal bone ash and dopes with wollastonite glass ceramics in different proportion,which provides theoretical reference for the research and development of biological glass ceramics and its practical clinical application.In this paper,wollastonite glass ceramics with A and B formula in Na2O-CaO-SiO2(NCS)system and wollastonite-hydroxyapatite glass ceramics with B formula were prepared by sintering method.The phase,sintering process,micro morphology,sintering performance,microhardness and compressive strength are test and analyze by DTA,XRD,SEM,EPMA,Computer Controlled Electronic Universal Testing Machine,Automatic Micro Hardness Tester,FTIR and other technologies.Through research,the following results have been achieved:1.The crystallization kinetics of A and B formulations was analyzed by DTA.The crystallization activation energy corresponding to each crystallization peak was calculated by Ozawa method,Augis-Bennett method and Kissinger method respectively.The results obtained by the three methods are basically the same.The activation energy of crystallization increases with the increase of crystallization peak temperature.The crystallization activation energy of formula A is lower than that of formula B.It is calculated that the crystal growth index n of each formula is less than 3,so the crystal in the system is surface crystallization and one-dimensional growth.The stability of the two groups of glass was calculated and compared by K(TP)criterion and glass network structure parameter Y.The K(TP)value of the A formula is 0.11 and the Y is 2.30.The K(TP)value of the B formula is 0.06 and the Y is 2.88.The calculation results show that the glass of formula A has a stronger crystallization ability.The XRD diffraction results of the samples sintered at the same heating rate show that the crystallization peak of the glass of formula A is stronger and the crystallinity is higher,which further verifies the calculation results.2.Two formulas of wollastonite glass ceramics were prepared by sintering method.The crystallization mechanism of the two formulas was explored.The crystallization sequence of each formula was analyzed,including the crystal phase transition.The crystallization model diagram was constructed.With the increase of sintering temperature,the crystallization sequence of formula A is Na2Ca3Si6O16→β-CaSiO3+ Na2Ca2Si3O9→β-CaSiO3→α-CaSiO3,and the crystallization order of formula B is β-CaSiO3+Na2Ca3Si6O16→β-CaSi3→α-CaSiO3.The sintering effect is the best when a single β-CaSiO3 crystal phase is precipitated in the sintered sample at 1000℃.The volume shrinkage of Formula A glass-ceramic is 19.7%,the porosity is 0.88%,the volume density is 2.32g/cm 3,and the micro hardness is 614.9HV,compressive strength is 305.5MPa,formula B glass-ceramic performance is slightly better than formula A,volume shrinkage is 24.8%,porosity is 0.38%,volume density is 2.18g/cm3,microhardness is 629.2HV,compressive strength is 313.5 MPa.3.The pig bones are calcined at high temperature to obtain ash.The hydroxyapatite from ash containing a small amount of Na,Mg,Cl and other Organic ions.Formula B glass-ceramics is doped with different proportions of ashes,and hydroxyapatite-wollastonite glass-ceramics are prepared by sintering method.With the increase of the amount of bone ash doping,the crystal phase content of wollastonite in the glass-ceramic sample gradually decreases,and the crystal phase content of hydroxyapatite increases.When the bone ash mass fraction is 40%,the grain distribution in the sample is uniform and the volume shrinkage is 19.3%,the porosity is 1.67%,the bulk density is 1.66g/cm3,the sintering performance is good,the microhardness is 484.5HV,and the compressive strength is 221 MPa,which meets the needs of bone repair materials.