Liu Changsheng, Shao Huifang, Chen Feiyue, Zheng Haiyan
Engineering Research Center for Biomedical Materials of the Ministry of Education, East China University of Science and Technology, Shanghai, 200237, China.
Biomaterials. 2003 Oct;24(23):4103-13. doi: 10.1016/s0142-9612(03)00238-2.
Effects of the granularity of the raw materials on the hydration and hardening process of calcium phosphate cement (CPC) composed of equimolar tetracalcium phosphate (TECP) and dicalcium phosphate anhydrous (DCPA) were investigated systematically. The variation of pH value in CPC slurry indicated that the control step of CPC hydration was the dissolution of DCPA under these experimental conditions. Reducing the particle size of DCPA could accelerate the hydration rate, and decreasing the particle size of TECP would expedite the dissolution of DCPA, which would obviously result in a faster hydration rate. The results of isothermal conduction calorimetry showed that reducing the particle size of TECP could increase the conversion ratio of starting materials to hydration products, which would lead to an increase in the compressive strength of the hardened body of CPC. The sample composed of the smallest particle size of DCPA and TECP obtained the compressive strength of 41 MPa, which would not attain the highest compressive strength, 49 MPa. The smaller the particle size of either DCPA or TECP, the shorter the setting time was. During the setting process of CPC, the microstructure progresses from a gel structure to an agglomeration-crystallization structure. The calculated values of setting time from the rheological model coincided with the experimental data very well. The parameters of AC impedance spectroscopy were closely correlated with the mean pore diameter and porosity of the CPC hardened body. The results of AC impedance spectroscopy further verified that a small particle size of raw materials could result in high hydration rate and the compressive strength of 49.1 MPa.
系统研究了原料粒度对由等摩尔磷酸四钙（TECP）和无水磷酸二钙（DCPA）组成的磷酸钙骨水泥（CPC）水化硬化过程的影响。CPC浆料pH值的变化表明，在这些实验条件下，CPC水化的控制步骤是DCPA的溶解。减小DCPA的粒径可加快水化速率，减小TECP的粒径会加速DCPA的溶解，这显然会导致更快的水化速率。等温传导量热法结果表明，减小TECP的粒径可提高原料向水化产物的转化率，这将导致CPC硬化体抗压强度的增加。由最小粒径的DCPA和TECP组成的样品获得了41MPa的抗压强度，未达到最高抗压强度49MPa。DCPA或TECP的粒径越小，凝结时间越短。在CPC的凝结过程中，微观结构从凝胶结构发展为团聚-结晶结构。流变模型计算的凝结时间值与实验数据吻合良好。交流阻抗谱参数与CPC硬化体的平均孔径和孔隙率密切相关。交流阻抗谱结果进一步证实，原料粒径小可导致高水化速率和49.1MPa的抗压强度。
