Prieto Valdés J J, Ortiz López J, Rueda Morales G, Pacheco Malagon G, Prieto Gortcheva V
ESFM, Instituto Politécnico Nacional. U.P. Adolfo López Matéos, Edif. 9 México D.F., 07738.
J Mater Sci Mater Med. 1997 May;8(5):297-301. doi: 10.1023/a:1018512428683.
Structural transformation and sintering processes of tricalcium phosphate (TCP) ceramics prepared from defective hydroxyapatite (Ca9HPO4(PO4)5OH) were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). Starting powders with Ca/P ratio approximately 1.5 were obtained by adding 0.5 l of 0.3 M H3PO4 solution to an equal volume of 0.45 M Ca(OH)2. In the prepared ceramics, the onset temperature for transformation of defective hydroxyapatite into TCP (witlokite) agrees with the onset temperature for sintering (800 degrees C). Sintering occurs through the formation of a fibrous structure, which resembles biological hard tissue. In the 1000-1200 degrees C range, these fibres coalesce into grains of up to 0.6 microm in size with a fibrous-laminar morphology. At the end of this sintering stage witlokite transforms into alphaTCP. At about 1450 degrees C, partial decomposition of alphaTCP into Ca2P2O7+Ca4P2O9 is observed. AFM observations suggest that Ca2P2O7 is segregated in the liquid state and increases the velocity of grain growth (up to 12 microm).
通过X射线衍射（XRD）和原子力显微镜（AFM）研究了由缺陷羟基磷灰石（Ca9HPO4(PO4)5OH）制备的磷酸三钙（TCP）陶瓷的结构转变和烧结过程。通过向等体积的0.45 M Ca(OH)2中加入0.5 l 0.3 M H3PO4溶液，获得了Ca/P比约为1.5的起始粉末。在制备的陶瓷中，缺陷羟基磷灰石转变为TCP（硅钙石）的起始温度与烧结起始温度（800℃）一致。烧结通过形成类似生物硬组织的纤维结构发生。在1000 - 1200℃范围内，这些纤维聚结形成尺寸达0.6微米的具有纤维层状形态的晶粒。在该烧结阶段结束时，硅钙石转变为α - TCP。在约1450℃时，观察到α - TCP部分分解为Ca2P2O7 + Ca4P2O9。AFM观察表明，Ca2P2O7以液态偏析并提高了晶粒生长速度（高达12微米）。
