氟化磷灰石和TCP双相转化及机理研究

Analysis of the Decomposition from Fluoridated Hydroxyapatite into TCP

为了增强羟基磷灰石(HA)的稳定性,通过溶胶凝胶法得到了氟化羟基磷灰石(FHA)。将FHA分别在720,800,900,1000和1100℃下烧结,形成FHA/Ca3(PO4)2(TCP)双相混合物。研究了氟含量对FHA热稳定性的影响。结果表明,F含量是决定FHA和TCP双相转换的关键因素。随着F含量的增加,TCP的量逐渐减少。当F含量x大于0.5时,结构更加稳定,TCP的转变数量减少;当F含量x小于0.5时,易产生TCP,并且形成了中空的孔结构。热分析结果显示:样品分解转化分为4个阶段,分别为吸附水的蒸发,失去结晶水,脱羟基和TCP的形成。转化温度与F含量遵循以下关系:T=250x+700(x<0.5)和T=750x+500(x≥0.5);F含量的增加增强了HA的热稳定性。

In order to increase the thermal stability of hydroxyapatite(HA),fluoridated hydroxyapatite(FHA) was synthesized by a sol-gel method.The results show that the duplex mixtures FHA and Ca3(PO4)2(TCP) are produced,when the samples are sintered at 720,800,900,1000 and 1100 ℃.The fluorine content is the key condition for the decomposition from FHA into TCP.The mass fraction of TCP decreases with the increasing of fluorine content.The mechanism of the decomposition shows that the structure of FHA becomes more stable when the F content is more than 0.5,but FHA decomposes into TCP easily when the fluorine content is less than 0.5,and the porous structure is formed regularly in the sintered FHA due to the decomposition from FHA into TCP.The TGA studies confirm that the mass loss of FHA is much less than that of HA.The decomposition of FHA has four steps: the evaporation of the absorbed water,the loss of the crystal water,the loss of hydroxyls and the formation of TCP.The functions of the temperature of decomposition and the fluorine content were simulated: T=250x+700(x<0.5) and T=750x+500(x≥0.5).The increase of the decomposition temperature indicates that F ion could increase the thermal stability of HA.