Suchanek W, Yashima M, Kakihana M, Yoshimura M
Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama, Japan.
Biomaterials. 1997 Jul;18(13):923-33. doi: 10.1016/s0142-9612(97)00019-7.
Several sintering additives for hydroxyapatite (HA) have been tested in order to enhance its sinterability without decomposing the HA and/or decreasing bioactivity and biocompatibility, additionally providing a weak interface for HA ceramics. The ion species of sintering additives were selected from those in the mineral constituents of hard tissues and bioactive glasses. After investigation of phase diagrams in the CaO-P2O5-additive systems, and analysis of physiochemical properties of the additives, several sintering aids for HA have been chosen. Subsequently, densification, phase composition, grain growth and fracture behaviour of HA containing 5 wt% of each additive, sintered at 1000-1100 degrees C, have been studied. H3BO3, CaCl2, KCl, KH2PO4, (KPO3)n and Na2Si2O5 did not enhance densification of HA. K2CO2, Na2CO3, KF and sodium phosphates improved the densification significantly. Expect for KCl and some sodium phosphates, all the additives caused formation of large quantities of undesired beta-tricalcium phosphate or CaO; therefore, they are not appropriate for HA. In the case of sodium phosphate additives, it was possible to avoid formation of CaO or beta-tricalcium phosphate by control of the additive quantity and chemical composition. beta-NaCaPO4 has been found to be an effective sintering agent which causes neither decomposition of HA nor formation of other undesired phases.
为了提高羟基磷灰石（HA）的烧结性，同时不使其分解以及降低生物活性和生物相容性，并为HA陶瓷提供一个弱界面，人们测试了几种用于HA的烧结添加剂。烧结添加剂的离子种类是从硬组织和生物活性玻璃的矿物成分中选取的。在研究了CaO-P2O5-添加剂体系的相图并分析了添加剂的物理化学性质之后，选择了几种用于HA的烧结助剂。随后，对含5 wt%每种添加剂、在1000-1100℃烧结的HA的致密化、相组成、晶粒生长和断裂行为进行了研究。H3BO3、CaCl2、KCl、KH2PO4、(KPO3)n和Na2Si2O5并未提高HA的致密化程度。K2CO2、Na2CO3、KF和磷酸钠显著改善了致密化。除了KCl和一些磷酸钠外，所有添加剂都会导致大量不需要的β-磷酸三钙或CaO形成；因此，它们不适用于HA。对于磷酸钠添加剂，通过控制添加剂的用量和化学成分，可以避免CaO或β-磷酸三钙的形成。已发现β-NaCaPO4是一种有效的烧结剂，它既不会导致HA分解，也不会形成其他不需要的相。
