SPS烧结制备生物活性镁黄长石陶瓷

钙硅基生物陶瓷具有良好的生物活性和细胞相容性, 在生物医疗领域具有广阔的发展前景。但是其粉体烧结性能差的缺点导致很难获得致密的陶瓷材料, 阻碍了其应用的进程。本研究采用化学共沉淀法制备了纯度高且烧结活性好的镁黄长石粉体, 然后采用放电等离子烧结技术(SPS)制备了镁黄长石陶瓷材料。通过X射线衍射(XRD)和扫描电子显微镜(SEM)表征了样品的组成结构和显微形貌, 并通过阿基米德法和模拟体液浸泡法分析了镁黄长石陶瓷样品的致密度和生物活性。研究结果表明, 采用SPS技术在1170℃、70 MPa保温5 min条件下可获得致密度超过99%的镁黄长石陶瓷材料。在模拟体液中浸泡3 d, 陶瓷样品表面出现磷酸盐的沉积, 浸泡7 d后生成了类骨羟基磷灰石, 说明SPS技术制备的致密镁黄长石生物陶瓷具有良好的诱导沉积类骨磷灰石能力。     

化学沉淀法制备纳米硅酸钙及其在模拟体液中的活性行为

以Ca(NO3) 2 ·4H2 O和Na2 SiO3·9H2 O为原料 ,聚乙二醇为分散剂 ,采用化学沉淀方法制备了直径 4 0nm的无定型纳米硅酸钙粉末 ,80 0℃热处理后得到平均直径 10 0nm的 β 硅灰石粉末。把两种粉末压制成块浸泡在模拟体液中 ,研究了两种粉体在模拟体液中的生物活性行为。结果表明 :由于无定型硅酸钙具有比β 硅灰石小的颗粒尺寸 ,且处于亚稳态 ,Ca2 的活性较大 ,无定型硅酸钙具有比 β 硅灰石较高的生物活性。在无定型硅酸钙表面不仅沉积了羟基磷灰石 ,而且也沉积了碳酸钙 ,以致于在浸泡初期阶段阻止了羟基磷灰石的沉积。经长时间浸泡后 ,无定型硅酸钙和 β 硅灰石表面都能沉积一层羟基磷灰石。     

离子束技术沉积羟基磷灰石薄膜的结构及溶解性能

分别采用离子束溅射和离子束增强沉积技术,以烧结羟基磷灰石（HA）陶瓷为靶材,在纯钛金属基片表面沉积HA薄膜．X光电子能谱分析表明：薄膜中Ca、P、O元素的化学态与所用HA陶瓷靶材相接近;相比HA靶材,薄膜表面存在CO₃^2-．X射线衍射分析表明：沉积薄膜均为非晶态结构,经650℃退火处理转变为结晶磷灰石．在模拟体液中的溶解实验揭示：薄膜仅与溶液中Ca、P和O存在离子交换;薄膜易降解,浸泡10天,样品经历了降解、再沉积过程;相比离子束溅射沉积膜,离子束增强沉积膜具有加速沉积Ca、P的能力．     

生物活性钛涂层

真空等离子喷涂的钛涂层经 ５．０ｍｏｌ／Ｌ ＮａＯＨ溶液处理后,将其浸泡在含 Ｃａ^２＋、ＨＰＯ_４^２－的模拟生理体液（ＦＣＳ和ＳＢＦ）中,考察涂层诱导羟基磷灰石生长过程,并评价其生物活性．用ＳＥＭ观察碱处理前后和在模拟生理体液中浸泡后钛涂层的形貌,用ＡＥＳ分析了碱处理前后钛涂层的表面成分;用ＸＲＤ、ＦＴ－ＩＲ和ＥＤＳ表征浸泡后涂层表面生长物的结构和成分;并测量了处理后钛涂层在浸泡过程中溶液中离子浓度和ｐＨ值的变化．结果表明,经处理的钛涂层在模拟生理体液中能诱导羟基磷灰石在其表面生长;在ＳＢＦ和ＦＣＳ分别形成碳酸羟基磷灰石层和含氧磷灰石的羟基磷灰石层．钛涂层的活性是由于碱处理后表面形成了网状和纤维状结构的Ｎａ－Ｔｉ－Ｏ化合物．这种化合物在模拟生理溶液中释放Ｎａ^＋,吸收Ｈ^＋;形成水化钛酸盐,诱导羟基磷灰石成核生长．     

粉体材料相关知识

正羟基磷灰石(HA)是一种具有良好应用前景的无机生物矿物材料,它是人体和动物骨骼的主要无机成分,因此具有良好的环境相容性和生物活性,在生物医用材料、环境功能材料、湿敏半导体材料、催化剂载体以及抗菌功能材料等方面有着广泛的应用。多孔羟基磷灰石是通过某种制作工艺,在制备羟基磷灰石生物陶瓷过程中使其内部具有多孔的结构。多孔结构的羟基磷灰石除具有一般陶瓷的优良性能外,因具有大孔和微孔结构而具有骨传导性,植入人体后,将被体液溶解和组     

磷酸钙在纳米羟基磷灰石／硅橡胶复合材料表面的仿生合成

将纳米羟基磷灰石，硅橡胶复合材料浸泡于模拟体液（SBF）中仿生合成了磷酸钙，利用IR、XRD、ICP和SEM等测试手段对表面沉积物进行表征．结果表明：在模拟体液中浸泡后，复合材料表面形成了分布均匀的以羟基磷灰石为主要成分的晶粒，表面羟基磷灰石的比例得到提高，生物学性能得以进一步改善；表明纳米羟基磷灰石，硅橡胶复合材料是一种生物活性材料．     

Ti6Al4V表面生物陶瓷涂层设计与生物活性研究

设计并制备了适用于Ti6Al4V表面涂覆层的生物陶瓷材料,将烧结后的陶瓷浸入模拟体液中,借助SEM、ICP、FTIR等分析技术研究其生物活性机理,结果表明所研制的陶瓷材料不仅具有和Ti6Al4V相匹配的热膨胀系数,且表面可沉积生成碳酸羟基磷灰石(HCA)具有良好的生物活性.     

磷灰石-硅灰石多孔玻璃陶瓷的制备与晶相结构研究

采用溶胶-凝胶法制备磷灰石-硅灰石(AW)生物活性玻璃陶瓷纳米前驱体粉末,前驱体粉末经热处理后,采用有机泡沫漫渍成型,烧结制备了多孔AW生物活性玻璃陶瓷.通过差热和热重分析、X射线衍射分析、红外图谱分析、扫描电镜、透射电镜等分析测试方法,对AW前驱体粉末的微观结构,及其在煅烧过程中的晶相转变进行了研究,确定了制备纳米级AW前驱体粉的最佳工艺条件,推测出微晶玻璃体中各晶相的析出温度,确定了溶胶-凝胶法制备多孔AW玻璃陶瓷的煅烧工艺,体外模拟体液浸泡实验表明材料具有较高的矿化功能和生物活性.     

PMMA/HA-GF复合材料在模拟体液中表面类骨磷灰石的形成

主要讨论了在聚甲基丙烯酸甲酯(PMMA)/无机玻璃纤维(GF)复合材料表面涂覆羟基磷灰石(HA)并经过处理后,在模拟体液中材料表面的接触角、类骨磷灰石的形成及表面微结构和形貌的变化.实验结果表明:增加PMMA/HA-FG复合材料表面的粗糙,可降低材料表面的接触角,使材料具有良好的润湿性;将材料在模拟体液中浸泡15d后,材料表面易形成团簇的、不连续的球状类骨磷灰石沉积物,主要成分为能与人体组织有良好结合的碳酸羟基磷灰石.     

等离子体喷涂氧化钛涂层的生物活性研究

以纳米TiO₂粉末为喷涂原料, 采用大气等离子体喷涂技术在医用钛合金上制备氧化钛涂层. 利用酸和碱溶液对氧化钛涂层表面进行生物活化处理, 体外模拟体液浸泡实验考察涂层的生物活性. 采用XRD、SEM、FTIR、EDS等测试技术对改性前后氧化钛涂层的生物活性进行表征. 结果表明: 氧化钛涂层和钛合金基体的结合强度较高, 其值高达40MPa, 涂层的耐模拟体液腐蚀性优于钛合金. 酸和碱溶液表面改性后的氧化钛涂层经模拟体液浸泡可在其表面生成含有碳酸根的羟基磷灰石(类骨磷灰石), 显示良好的生物活性.     

Morphology and immersion behavior of plasma-sprayed hydroxyapatite/bioactive glass coatings

A series of hydroxyapatite/bioactive glass (HA/BG) coatings have been plasma-sprayed on Ti6Al-4V substrate using HA/BG powders that were prepared by both sinter-granulation and direct mixing methods. The morphology and immersion behavior of these coatings in a simulated body fluid (SBF) were investigated. The results showed that in-house fabricated BG and sinter-granulated HA powders were irregularly shaped and dense. When 5 wt % or more BG was added in HA, the powder became rough and porous. X-ray diffraction (XRD) patterns showed that the presence of BG enhanced the decomposition of HA structure during fabrication of the powders. Reasonably high bond strengths were obtained from all coatings. The granulated type HA/BG coatings showed no significant differences in bond strength from the mixed type HA/BG coatings. The plasma spray process itself and the presence of BG enhanced the decomposition of apatite. Surface morphology of all sinter-granulated type coatings was similar to that of monolithic HA coating, that was comprised of patches of smooth and shiny glassy film and irregularly-shaped particles on its surface. The dissolution depth of plasma-sprayed coatings immersed in SBF was largely dependent on the type and composition of the coating. Granulated type HA/BG coatings were much less dissolvable than monolithic HA or mixed type HA/BG coatings. It seems that the presently used granulation method for the preparation of HA/BG powders plays a predominant role in determining the dissolution behavior of the plasma-sprayed coatings. ©©2000 Kluwer Academic Publishers     

Immersion behavior of hydroxyapatite (HA) powders before and after sintering

The immersion behavior of two different hydroxyapatite (HA) powders before and after sintering was investigated by soaking them in simulated body fluid (SBF) for various periods. The results showed that the mechanism of formation of bone-like apatite on the two HA powders was different due to their different phase composition. Moreover, after being sintered at a proper elevated temperature, the bioactivity of HA powders was increased.     

Fabrication and corrosion behavior of HA/Mg-Zn biocomposites

The thermal-treated hydroxyapatite (HA) particles, Mg and Zn powders were used to prepare the HA/Mg-Zn composites with different HA contents by means of powder metallurgy technology. The microstructures, formation phases, and corrosion behaviors in simulated body fluid (SBF) were studied in comparison with pure magnesium and HA/Mg composites fabricated by the same preparation technology. As a result, no evident reaction happened between HA particles and Mg matrix during sintering process, and Zn atoms diffused into Mg matrix to form a single phase Mg-Zn alloy matrix. The addition of HA particles changed the corrosion mechanism of Mg matrix. During the corrosion process, HA particles would adsorb and Ca²⁺ ions efficiently and induce the deposition of Ca-P compounds on the surface of composites. HA could improve the corrosion resistance of magnesium matrix composites in SBF and restrain the increase of pH of SBF. Furthermore, the addition of Zn was favorable to improve the corrosion resistance of HA/Mg composites due to the densification of composites and the formation of Mg-Zn alloy matrix.     

Nanosized hydroxyapatite powders derived from coprecipitation process

Nanosized hydoxyapatite (Ca₁₀(PO₄)₆(OH)₂ or HA) powders were prepared by a coprecipitation process using calcium nitrate and phosphoric acid as starting materials. The synthesized powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) specific area measurment techniques. Single phase HA, with an average grain size of about 60 nm and a BET surface area of 62 m²/g, was obtained. No grain coarsening was observed when the HA powders were heated at 600°C for 4 hours. HA ceramics were obtained by sintering the powders at temperatures from 1000°C to 1200°C. Dense HA ceramics with a theoretical density of 98% and grain size of 6.5 m were achieved after sintering the HA powders at 1200°C for 2 hours. HA phase was observed to decompose into tricalcium phosphate when sintered at 1300°C. The microstructure development of the sintered HA ceramics with sintering temperature was also characterized and discussed.     

高强度羟基磷灰石纳米陶瓷的构建及其促成骨细胞活性研究

本研究旨在研究羟基磷灰石(HA)前驱粉体与所制备陶瓷之间的关系,制备具有优良力学性能及成骨活性的HA纳米陶瓷.采用三种HA前驱粉体,即40℃合成的HA-40粉体、以PEG为模板40℃合成的HA-40PEG粉体和80℃合成的HA-80粉体,系统研究了前驱粉体对陶瓷性能的影响.结果显示,HA-40、HA-40PEG和HA-...     

Physical and mechanical properties of Si3N4 sintered from shock-activated and unshocked powders

Si₃N₄ powder was shock activated using impact from a sabot accelerated in a light gas gun. The surface area of the shocked powder increased with the square of the impact velocity. The surface energy per gram was shown to increase linearly with the kinetic energy of the sabot (including flyer plate). The shocked (green) densities of the resulting pellets were between 60 and 70% of theoretical density using calculated impact pressures between 0.16 and 1.45 G Pa. The unshocked samples achieved 90 and 98% theoretical density after sintering; lower final densities in the shocked samples were attributed to microcracks which could not be completely eliminated by sintering. The values of hardness and fracture toughness were measured (after sintering) using an indentation technique. These values were higher for the shocked samples (measured in microcrack free areas) than for the unshocked samples.     

Synthesis of Si-substituted hydroxyapatite by a wet mechanochemical method

Si-substituted hydroxyapatites with up to 2.0 wt% Si content, have been prepared by a wet mechanochemical method to obtain improved biocompatibility. From XRD, ICP and FTIR analysis, single phase of modified hydroxyapatite with PO₄³⁻ partially substituted by SiO₄⁴⁻ was confirmed. The XRD data indicated that some changes take place in the HA lattice with varying Si contents in Si–HA samples. The in-vitro bioactivity of the as-obtained materials was determined by soaking the materials in SBF, monitoring the changes of chemical composition and pH value of the SBF solution, whereas the microstructures of the soaked powders were observed by TEM.     

Fabrication and corrosion behavior of HA/Mg-Zn biocomposites

The thermal-treated hydroxyapatite (HA) particles, Mg and Zn powders were used to prepare the HA/Mg-Zn composites with different HA contents by means of powder metallurgy technology. The microstructures, formation phases, and corrosion behaviors in simulated body fluid (SBF) were studied in comparison with pure magnesium and HA/Mg composites fabricated by the same preparation technology. As a result, no evident reaction happened between HA particles and Mg matrix during sintering process, and Zn atoms diffused into Mg matrix to form a single phase Mg-Zn alloy matrix. The addition of HA particles changed the corrosion mechanism of Mg matrix. During the corrosion process, HA particles would adsorb PO₄³⁻ and Ca²⁺ ions efficiently and induce the deposition of Ca-P compounds on the surface of composites. HA could improve the corrosion resistance of magnesium matrix composites in SBF and restrain the increase of pH of SBF. Furthermore, the addition of Zn was favorable to improve the corrosion resistance of HA/Mg composites due to the densification of composites and the formation of Mg-Zn alloy matrix.     

Calcining influence on the powder properties of hydroxyapatite

The effect of different calcination temperatures on the powder characteristics and the sintered density of synthetic hydroxyapatite (HA) powders, produced using two different processing routes, was examined. Powders were produced by either drying, milling and sieving an as-precipitated HA or by spray-drying a slurry of precipitated HA. Calcining the two powders at temperatures between 400 and 1000 °C did not significantly affect the powder particle size. The specific surface areas of the two powders, however, were reduced from 70–80 m²/g for a calcination temperature of 400 °C to approximately 5–7 m²/g for 1000 °C. Analysis of the surfaces of the HA powders using scanning electron microscopy (SEM) illustrated the coarsening and subsequent sintering of the sub-micron crystallites that constitute a powder particle as the calcination temperature increased, corresponding to the decrease in surface area of the powders. The sintered densities of the final ceramics were not significantly affected by calcining the powders. Microhardness measurements of ceramics prepared from powders calcined at different temperatures showed no significant variations with calcination temperature or powder processing method. The results of this study have illustrated that for applications where HA may be used in powder form, for example in plasma-spraying and for the production of HA-polymer composites, calcining the HA will significantly affect the powder properties, namely the surface area and morphology of the powders. For applications requiring HA in a dense ceramic form, for example as granules or blocks, calcining the powders does not significantly affect the properties of the final ceramic.     

Effect of solid/solution ratio on apatite formation from CaSiO<Subscript>3</Subscript> ceramics in simulated body fluid

The effect of the solid/solution (S/S) ratio on apatite formation from CaSiO₃ ceramics in simulated body fluid (SBF) was investigated. CaSiO₃ ceramics with a Ca/Si ratio of 0.91 were prepared by sintering CaSiO₃ powder coprecipitated from ethanol solutions of Ca(NO₃)₂⋅4H₂O and Si(OC₂H₅)₄ using NH₄OH as the precipitant. These ceramics were reacted with SBF at S/S ratios of 1.0, 2.5 and 8.3 mg/ml at 36.5 ^∘C for various times. Formation of apatite was observed at all the S/S ratios after soaking for 1 day. The amount and microstructure of the apatite obtained at a S/S ratio of 8.3 mg/ml, however, differed largely from the product formed at the other two S/S ratios. The apatite formed at S/S = 8.3 mg/ml was of smaller particle size, formed in smaller amount and with less preferred orientation of the (00l) of apatite crystals compared with those formed at S/S = 1.0 and 2.5 mg/ml. An increase of Ca and decrease of the P components occurred in the soaked SBF at S/S = 8.3 mg/ml, the changes being much more marked than with the other two S/S ratios. These differences in the concentration changes in SBF at different S/S ratios are attributed to the difference in the apatite formation from the CaSiO₃ ceramics.