医用双相磷酸钙陶瓷的制备工艺研究

医用双相磷酸钙（BCP）陶瓷是β-磷酸三钙（β-TCP）和羟基磷灰石（HA）的复合体,其成分与骨矿物组成类似,在生理环境下能发生不同程度的降解,被组织吸收。通过化学沉淀法制备纳米羟基磷灰石,然后通过可溶性钙盐和磷酸盐反应工艺制得的β-磷酸三钙,最后将二者进行机械复合而制得双相磷酸钙,将所得样品用X射线衍射仪（XRD）对样品进行了表征。结果显示：所得的双相磷酸钙中掺杂有β-焦磷酸钙,但是它的结晶较好,并且可以改善双相磷酸钙陶瓷的力学性能。     

α-磷酸三钙骨水泥自固化制备多孔磷酸钙复相陶瓷

以聚氨酯泡沫为多孔模板,α-磷酸钙骨水泥为浆料体系,将浸渍法和骨水泥自固化特性相结合,制备大孔尺寸为200～400 μm、贯穿式微孔尺寸约为1μm的多孔磷酸钙复相陶瓷支架.研究了分散剂聚丙烯酸钠对羟基磷灰石成核、生长的影响,以及烧成温度与相组成的相关性.结果表明:浆料中分散剂聚丙烯酸钠对羟基磷灰石的成核有明显抑制作用;骨水泥水化反应过程中生成的针状、片状羟基磷灰石通过交联形成微孔结构,可避免干燥时裂纹的产生;经1 200℃烧结的多孔陶瓷支架由羟基磷灰石、β-磷酸三钙和少量未水化完全的α-磷酸三钙组成.     

可降解β-磷酸三钙的制备及应用

磷酸三钙、羟基磷灰石以及它们的混合物等磷酸钙陶瓷，其成分与骨矿物组成类似，生物学相容性好。它们在生理环境下能发生不同程度的降解，被组织吸收，称为生物降解或生物吸收。本文对可降解β-磷酸三钙进行了综述，介绍了可降解β-磷酸三钙的制备、应用及以后研究的发展趋势。     

多孔双相钙磷钛合金微弧氧化膜层的制备及生物相容性

为克服钛合金生物膜层单一相的缺陷,以Ti6A14V合金为基体,用微弧氧化法制得具有双相钙磷复合陶瓷膜层(BCP)的钛合金器件.通过控制工作液成分制得由不同比例的β-磷酸三钙(β-TCP)和羟基磷灰石(HA)组成的多孔性复合膜层.研究了电源占空比对BCP膜孔隙率和孔径大小的影响.采用能谱仪和X射线衍射仪分析了BCP膜层的...     

磷酸钙生物陶瓷新工艺

近来，一种高强磷酸钙生物陶瓷生产新工艺问世海外。该工艺的问世有效消除了强度与相对密度（生物适应性）之间的技术冲突，为医学应用提供强度高、生物适应性好的磷酸钙生物陶瓷。据介绍，该工艺是将平均粒径为3～30μm的磷酸钙化合物如羟基磷灰石、氟磷灰石、碳酸磷灰石等磷灰石类、磷酸二钙、磷酸三钙或磷酸四钙混合、成型，送入大气炉中于1050～1250℃下预烧一定时间，     

羟基磷灰石及其晶须的功能

羟基磷灰石又称氢氧磷灰石,是磷酸钙系无机物分子式为Ca10（PO4）6（OH）2,相对分子质量1504．61。日本学者将羟基磷灰石粉末加入环氧树脂组成物中,制得环氧树脂胶粘剂,用于粘接铝合金,可使耐久性大幅度提高。研究表明,从羟基磷灰石中游离出的磷酸离子与铝合金表面螯合,有效防止了水和氯化物离子向粘接界面侵蚀。尤其耐热水性明显改善,从而具有优异的粘接耐久性。采用羟基磷灰石可制备羟基磷灰石骨水泥,作为医用胶粘剂用于硬组织的粘接和固定。     

几种阳离子置换磷酸钙生物陶瓷的XRD分析

磷酸钙生物陶瓷中存在阳离子置换现象。对可吸收Ｃａ２ＮａＫ（ＰＯ４）２陶瓷,湿法合成的含锶和空镧羟基磷灰石进行Ｘ射线衍射（ＸＲＤ）分析发现：Ｃａ２ＮａＫ（ＰＯ４）２可看作Ｎａ＾＋在ＫＣａＰＯ４中的固溶体,其热稳定性变差,分解出磷酸三钙和氧化钙,相同配普下含镧羟基磷灰石的衍射峰的宽化和弱化更严重,其热稳定性更差。     

双相磷酸钙多孔陶瓷的制备

以羟基磷灰石为原料,壳聚糖微球为成孔剂,明胶为分散剂,采用注浆法制备多孔双相磷酸钙陶瓷。通过X射线衍射和扫描电子显微镜对烧结体相组成、微观结构、孔径和孔分布进行了分析和观察。结果表明：起始粉末粒径为260nm的试样,在：1000℃～1180℃范围内烧结,可获得不同β-TCP/HA比的双相多孔陶瓷。与单相β-TCP陶瓷相比,β-TCP／HA双相多孔陶瓷的断口呈现出凸凹不平。     

骨组织工程支架材料磷酸钙双相生物陶瓷的研究进展

双相磷酸钙(biphasic calcium phosphate,BCP)生物陶瓷材料在整型外科领域是一类重要的骨修复材料。该材料由稳定相羟基磷灰石(hydroxyapatite,HA)和可溶解相β-磷酸三钙(β-tricalcium phosphate,β-TCP)双相平衡优化得到,其生物活性及生物降解性可调。模拟人体自然骨结构的多孔型BCP适宜细胞及骨组织的长入,是一类优异的骨组织工程支架材料。概述了BCP生物陶瓷材料的研究历史、制备工艺及材料表征;评价了多孔型BCP陶瓷的孔隙结构、力学性能及生物学性能;综合了多孔型BCP陶瓷作为骨组织工程支架材料的研究方向;并展望了组织工程化的BCP支架材料的研究未来。     

双相钙磷生物陶瓷研究进展

相钙磷生物陶瓷是一类由羟基磷灰石[HA,Ca10(PO4)6(OH)2]和β-磷酸三钙[β-TGP,Ca3(PO4)2]按不同比例组成的硬组织替换材料。由于其成分与人体硬组织的无机成分基本一致,且综合了HA的优异的生物相容性和β-TCP的生物降解性,因而成为硬组织修复、替换材料的研究热点。简要综述了双相钙磷陶瓷的制备、性能及应用进展。     

Synthesis and characterization of hydroxyapatite/β-tricalcium phosphate nanocomposites using microwave irradiation

Microwave assisted synthesis method is a relatively new approach employed to decrease synthesis time and form a more homogenous structure in biphasic calcium phosphate bioceramics. In this study, nanocrystalline HA/β-TCP composites were prepared by microwave assisted synthesis method and, for comparison reason, by conventional wet chemical methods. The chemical and phase composition, morphology and particle size of powders were characterized by FTIR, XRD and SEM, respectively. The use of microwave irradiation resulted in improved crystallinity. The amount of hydroxyapatite phase in BCP ranged from 5% to 17%. The assessment of bioactivity was done by soaking of powder compacts in simulated body fluid (SBF). The decreasing pH of the solution in the presence of β-TCP indicated its biodegradable behavior. Rod-like hydroxyapatite particles were newly formed during the treatment in SBF for microwave assisted substrate synthesis. In contrast, globular particles precipitate under same conditions if BCP substrates were synthesized using conventional wet chemical methods.     

Regulating the multifactor during wet chemical synthesis to obtain calcium phosphate powders with controllable phase purity for bone repair

Calcium phosphate ceramics are widely used as bone repair materials owing to their excellent biocompatibility, bone conductivity, bone induction, and degradability. Although there are many methods for synthesizing calcium phosphate and controlling its phase composition, it is necessary to explore effective preparation methods by understanding the formation of calcium phosphate and its influencing factors. In this study, calcium phosphate powders with controllable phase compositions were synthesized using a wet chemical precipitation method by adjusting the process parameters (aging time, bipolar solution, initial Ca-P molar ratio, capping agent concentration, and system concentration). Subsequently, a certain biphasic proportion of (biphasic calcium phosphate, BCP) products was prepared, and pure (β-tricalcium phosphate, β-TCP) can be obtained according to the customer's requirements. BCP ceramics with desired phase compositions were obtained by pressing and sintering different calcium-deficient powders. Specifically, β-TCP powder with a purity of 99.83 wt% was obtained when the aging time, bipolar solution, initial Ca-P molar ratio, capping agent concentration, and system concentration were 0 h, 50% ethanol, 1, 0.27 M, and 0.0135 M, respectively. The BCP synthesized in this study shows great application potential in the field of bone tissue repair materials.     

Processing and properties of biphasic calcium phosphates bioceramics obtained by pressureless sintering and hot isostatic pressing

Calcium phosphate powders were obtained from coprecipitation method using diammonium phosphate and calcium nitrate solutions. The adjustment of experimental parameters and Ca/P initial ratio allowed synthesizing stoichiometric HA and β-TCP powders and four biphasic calcium phosphates (BCP) with compositions equal to 20/80, 40/60, 60/40, 80/20, of HA and TCP respective in mass. Two sintering techniques, pressureless sintering and hot isostatic pressing (HIP) were performed to compare the sinterability of the stoichiometric and biphasic compounds. By pressureless sintering, densities higher than 98% were obtained. Results illustrate the negative impact of hydroxyapatite on the densification of BCP but its benefit effect on grain growth inhibition. After HIP treatment, transparent ceramics were obtained. The mechanical behavior of these fully densified compounds was examined in order to determine the role of the chemical composition on mechanical properties.     

Sintering parameters study of a biphasic calcium phosphate bioceramic synthesized by alcoholic sol-gel technique

In the sintering of biphasic calcium phosphate bioceramics (BCP) can occur phases transformations accompanied by a sudden thermal expansion due to different coefficients of thermal expansion of each phase, which generates internal stress concentrations inducing undesired cracks within the sample. Therefore, this work aimed to study the sintering parameters of a BCP, composed of hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP), synthesized by the alcoholic sol-gel technique, in order to evaluate the better conditions for avoiding defect generation. BCP powders were uniaxially cold-pressed at 300 MPa and air-sintered at 1070 °C/2 h (BCP1070 sample) and 1130 °C/2 h (BCP1130 sample), with heating rates of 10 °C/min and 5 °C/min, respectively. Samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, relative density determination, Vickers hardness test, and nanohardness tests. The results displayed that the assessed sintering parameters were suitable for promoting a satisfactory particle consolidation. The transformation from HAp to β-TCP occurred simultaneously with grain growth and material densification under all conditions. The mechanical tests revealed that BCP1070 and BCP1130 samples have different behaviour when analyzed micro or nanostructurally. But, the heating rate (10 °C/min) combined with the sintering temperature (1070 °C) anabled to obtain a suitable sinterability with samples presenting smaller grain size and without defects. Further, it kept the microporosity which is an essential property for application in bioceramic materials.     

Effects of strontium substitution on the phase transformation and crystal structure of calcium phosphate derived by chemical precipitation

This study focused on the effects of strontium substitution on the phase transformation and crystal structure of calcium phosphate. Chemical precipitation was used to prepare Sr-doped hydroxyapatite (HA) precursor powders. The phase transformation of the as-prepared samples during sintering was analyzed. The powders were characterized by X-ray diffraction, X-ray fluorescence spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Quantitative analysis of the phase content and fine structure was performed by Rietveld refinement. Sr doping was found to facilitate the phase transformation from HA to beta-tricalcium phosphate (β-TCP) at 1000 °C. The β-TCP content increased with increasing Sr content, causing a decline in the ratio of HA to β-TCP. With Sr contents of ≤5 mol%, HA remained the major phase in the biphasic mixtures; in contrast, with Sr contents of ≥15 mol%, the mass fraction of β-TCP exceeded 50%. The incorporation of Sr²⁺ into HA and β-TCP caused the lattice parameters of both phases to increase. Additionally, Sr incorporation slightly enhanced the binding energy of Ca. The study confirmed that Sr doping could be used to modulate the phase fractions of HA and β-TCP. The effective partial substitution of Sr in both HA and β-TCP makes these materials promising for bone repair.     

Effect of the HA/β-TCP Ratio on the Biological Performance of Calcium Phosphate Ceramic Coatings Fabricated by a Room-Temperature Powder Spray in Vacuum

Four calcium phosphate ceramic coatings, the less soluble hydroxyapatite (HA) coating, the more soluble β-tricalcium phosphate (β-TCP) coating, and two biphasic calcium phosphate (BCP) coatings with HA/β-TCP ratios of 70/30 and 30/70 were fabricated by spraying each corresponding powder onto a titanium substrate at room temperature (RT) in a vacuum, in order to investigate the effect of the HA/β-TCP ratio on the dissolution behavior and the cellular responses of the coating. No secondary phases, except for HA and β-TCP, were observed for the coatings in the X-ray diffraction results. The coating compositions were almost the same as those of the starting powders because the coating was conducted at RT. Microscopic examination of the coatings revealed crack-free and dense microstructures. The BCP coatings exhibited dissolution rates intermediate between those of the pure HA and β-TCP coatings. The dissolution rate of the coatings was largely dependent on their HA/β-TCP ratio. The cell proliferation and differentiation results indicated that the cellular responses of the coatings were not proportional to their dissolution rates. The 3HA–7TCP (HA/β-TCP ratio of 30/70) coating exhibited an optimal dissolution rate for excellent biological performance.     

Properties of calcium phosphates ceramic composites derived from natural materials

In this study, ceramics containing mixed phases of hydroxyapatite/beta-tricalcium phosphate (HA/β-TCP) were fabricated by a solid-state reaction technique. The HA powder was synthesized from cockle shells while the β-TCP powder was synthesized from egg shells. Pure HA and β-TCP fine powders were successfully obtained. The HA and β-TCP were mixed and subjected to a thermal treatment up to 1100 °C. To form the mixed phase ceramics, the resulting powders were sintered at 1350 °C. Effects of HA concentration on the properties of the studied ceramic were investigated. X-ray diffraction analysis revealed that all samples presented multiphase of calcium phosphate compounds. Average grain size of the ceramics decreased with the HA additive content. The 75 wt% HA ceramic showed the maximum hardness value (5.5 GPa) which is high when compared with many calcium phosphate ceramics. In vitro bioactivity test indicated that apatite forming increased with the HA additive content. To increase antibacterial activity, selected ceramics were coated with AgNO₃. Antibacterial test suggested that an Ag compound coating on the ceramics could improve the antibacterial ability of the studied ceramics. In addition, the antibacterial ability for the Ag coated ceramics depended on the porosity of the ceramics.     

A Novel Biphasic Bone Scaffold: β-Calcium Phosphate and Amorphous Calcium Polyphosphate

Calcium polyphosphate (CPP) was added to hydroxyapatite (HA) to develop a novel biphasic calcium phosphate (BCP). The effects of varying CPP dosage on the sintering property, the mechanical strength, and the phase compositions of HA were investigated. Results showed that CPP reacted with HA and produced β-calcium phosphate (β-TCP) and H₂O and that an excessive dosage of CPP (>10 wt%) obtained a novel BCP of β-TCP/amorphous-CPP, while a lesser dosage of CPP (<10 wt%) obtained a traditional BCP (HA/β-TCP). The porous β-TCP/amorphous-CPP scaffolds (porosity of 66.7%, pore diameter of 150–450 μm, and compressive strength of 6.70±1.5 MPa) were fabricated and their in vitro degradation results showed a significant improvement of degradation with the addition of CPP.