Hydrothermal Preparation of Calcium Hydroxyapatite Powders

Calcium hydroxyapatite powders were prepared by hydrothermal reactions of calcium pyrophosphate and calcium oxide. Primary particles of the hydroxyapatite obtained were spherical with diameters less than 0.2 μm, and small prismatic crystals were rarely observed in some fields. The effects of temperature, pressure, and soaking time on the structural features of the resultant powders were also studied by means of XRD and SEM and were smaller than expected for the ranges investigated.     

Reaction Sintering and Mechanical Properties of Hydroxyapatite–Zirconia Composites with Calcium Fluoride Additions

The effects of calcium fluoride (CaF₂) additions on the densification and mechanical properties of hydroxyapatite–zirconia composites (HA–ZrO₂) were investigated. When small amount of CaF₂ was added, the density of the composites was markedly enhanced. The reactions of HA with CaF₂, which led to the formation of fluorapatite (FA), were attributed to the observed improvements in densification. When HA–20-vol%-ZrO₂ composites were sintered, with the addition of 5 vol% of CaF₂, in air at 1300°C, the density of the specimen approached 98% of the theoretical value. The flexural strength and fracture toughness of the composites were also improved, as a result of the enhanced densification.     

水热合成纳米羟基磷灰石粉末及其结构表征

羟基磷灰石 (HA)已广泛用作人体硬组织的修复和替换材料 ,采用CaCO3 和CaHPO4·2H2 O的混合物为前驱物 ,在 2 0 0℃下经 8h的水热处理获得了晶粒完整、粒度在 10 0nm以下的柱状或针状HA晶体。借助X射线衍射(XRD)、扫描电镜 (SEM)及红外光谱 (FTIR)对HA的晶相组成、形貌、大小及化学组成进行了分析。实验结果表明 :当前驱物钙磷比Ca/P为 1.2时 ,水热产物主要为Ca2 P2 O7,前驱物钙磷比Ca/P为 1.6 7和 2 .0时 ,水热产物只有HA ,并且随Ca/P比的增加 ,进入磷灰石结构的结构CO3 2 -的量增加 ,引起晶格畸变 ,晶粒尺寸降低。这种纳米晶体在形态、结构和组成上与人骨相似 ,更有利于作为生物医用材料应用     

六偏磷酸钠对纳米羟基磷灰石水中分散行为的影响

本文通过对纳米羟基磷灰石/六偏磷酸钠分散体系粒径分布和Zeta电位的测定,研究了六偏磷酸钠对纳米羟基磷灰石水中分散行为的影响.结果显示,在六偏磷酸钠很宽的浓度范围内,羟基磷灰石都能够稳定存在.六偏磷酸钠是羟基磷灰石在水中优良的分散剂.当NaP/HA=12.5(重量比)时获得高分散性纳米羟基磷灰石溶胶,该溶胶含有88%粒径在65～86nm范围的羟基磷灰石粒子.     

多孔羟基磷灰石的研究现状与发展

本文综合论述了多孔羟基磷灰石的制备工艺及基本原理,介绍了多孔羟基磷灰石的各种性能,并提出了多孔羟基磷灰石研究中现存的一些问题,预测了今后研究的发展方向.     

羟基磷灰石晶体在有机膜上的受控生长

研究了十六胺有机膜对羟基磷灰石(HAP)的晶体结构、形核、晶体形貌和结晶学定向生长的调控作用及其机理.结果表明:无有机膜时,生成物为磷酸八钙(OCP)和羟基磷灰石(HAP)的混合物,其生长速率很低且晶体排列无一定规则;在十六胺有机膜的调控下,生成物为规则排列、沿(0001)定向生长、结晶良好的片状纳米羟基磷灰石晶体,且其形核和生长速率均很高十六胺有机膜上有大量极性强、电荷密度高的NH 3基团,它们通过静电作用在有机膜/溶液界面处形成局域过饱和浓度,促进羟基磷灰石晶体的形核;另一方面,十六胺有机膜的二维晶格尺寸与HAP(0001)面的晶格参数具有良好的匹配关系,构造了一个有利于HAP以(0001)面形核生长的结构框架,促进了HAP相沿(0001)方向的定向生长.     

化学沉淀法制备纳米HAP粉体的工艺优化

用化学沉淀法制备出了纳米级的HAP粉体 ,讨论了不同工艺参数对化学沉淀法制备的HAP粉体性能的影响 .用X射线衍射、红外光谱以及TEM对所制粉体进行了分析 .测定结果表明 :煅烧后粉体的结晶程度明显提高 ,在进行煅烧时以 90 0～ 10 0 0℃煅烧 1h以下为宜 .反应温度及保温时间的影响较小     

Deformation behavior of skeletal composites under mechanical loading

The deformation behavior of ceramic-metal composites with a bulk-linked metal skeleton made of highly porous cellular nickel and a stainless wire mesh is examined. It is established that samples of skeletal ceramics remain intact after all types of destructive tests and show high plasticity and strain and fracture energies. A technique is developed for producing ceramics with a bulk-linked metal skeleton by filling a highly porous framework with a ceramic powder and subsequent pressing and sintering of the composite. The technique is tested for two types of skeletal ceramics: structural ceramics such as pyroceramics-highly porous cellular nickel and bioceramics such as hydroxyapatite-highly porous stainless wire skeleton. The hydroxyapatite-based composite has lower bending strength and shock bending energy but higher plasticity and nondestructability than the pyroceramics-based composite. __________ Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 7–8 (456), pp. 82–90, 2007.     

不同孔隙率锶磷灰石陶瓷体内异位成骨能力的比较

采用健康兔的骨髓组织,体外培养,诱导分化为成骨细胞,分别与孔径约为450～700μm、孔隙率分别为50%、60%、70%的Sr-HA以及孔隙率为70%的纯羟磷灰石陶瓷体复合,自体回植到兔背脊肌内.同时以未复合细胞的相同孔隙率的陶瓷材料作为对照,植入后4周、12周和24周取材,行四环素荧光染色观察,定量计算各组陶瓷材料新骨的形成量和速度,比较不同孔隙率锶磷灰石陶瓷材料的异位成骨能力.结果表明,复合成骨细胞的各组陶瓷在植入兔背脊肌内4周后均有新骨形成,随着植入时间的延长,骨组织的数量不断增加;孔隙率为70%的Sr-HA陶瓷和HA陶瓷的新骨形成数量和速度明显优于低孔隙率的Sr-HA陶瓷.四环素荧光标记还显示未复合成骨细胞的Sr-HA陶瓷和HA陶瓷孔隙内也有荧光沉积.Sr-HA多孔陶瓷是较理想的骨组织工程支架材料,成骨细胞复合Sr-HA陶瓷用于骨缺损的修复,具有广阔的临床应用前景.     

机械化学法合成羟基磷灰石过程中的"爆炸式"反应

应用机械化学原理,研究了在振动磨样机中由磷酸二氢钙(MCPM)和氢氧化钙合成羟基磷灰石(HAP)过程的动力学机制,并建立了相应的动力学模型.结果表明,合成过程为生成中间产物二水磷酸氢钙(DCPD)的两步式反应,其中第二步反应在第一步反应结束后才开始,并且在很短的时间内(＜30s)迅速完成,即发生了"爆炸式"反应,反应过程可用类Avrami方程进行表征.探讨了发生"爆炸式"反应的可能机理.