电沉积法制备磷酸钙生物活性陶瓷涂层

综述了用电沉积法在金属生物材料表面涂敷磷酸钙生物活性陶瓷的工艺,分析了电沉积工艺的特点,并介绍了制备金属－羟基磷灰石复合涂层的复合电沉积工艺。     

Calcium Phosphate Cements Prepared by Acid–Base Reaction

We investigated the characteristics of calcium phosphate cements (CPC) prepared by an exothermic acid–base reaction between NH₄H₂PO₄-based fertilizer (Poly-N) and calcium aluminate compounds (CAC), such as 3CaO · Al₂O₃ (C₃A), CaO · Al₂O₃ (CA), and CaO · 2Al₂O₃ (CA₂), in a series of integrated studies of reaction kinetics, interfacial reactions, in-situ phase transformations, and microstructure development. Two groups were compared: untreated and hydrothermally treated CPC specimens. The extent of reactivity of CAC with Poly-N at 25°C was in the following order: CA > C₃A ≫ CA₂. The formation of a NH₄CaPO₄· x H₂O salt during this reaction was responsible for the development of strength in the CPC specimens. The in-situ phase transformation of amorphous NH₄CaPO₄· x H₂O into crystalline Ca₅(PO₄)₃(OH) and the conversion of hydrous Al₂O₃ gel →γ-AIOOH occur in cement bodies during exposure in an autoclave to temperatures up to 300°C. This phase transformation significantly improved mechanical strength.     

Calcium Phosphate Materials Prepared from Precipitates with Various Calcium:Phosphorus Molar Ratios

Depending on the calcium:phosphorus molar ratio of the initial precipitates determined by precipitation conditions (calcium:phosphorus molar ratio of reactants and pH of reaction environment), after sintering at 1250°C, monophase, biphase, or triphase ceramics consisting of hydroxyapatite, β-tricalcium phosphate, α-tricalcium phosphate, and calcium oxide were obtained. The phase composition and properties—i.e., density, shrinkage, hardness, bending strength, and roughness—of the fractured surfaces of the isostatically re-pressed sinters were determined.     

微波烧结法制备TCP/TTCP复合生物陶瓷材料的研究

采用微波烧结方法制备TCP/TTCP复合磷酸钙生物陶瓷材料,以四水硝酸钙(Ca(NO3)2·4H2O)和磷酸氢二铵((NH4)2HPO4)为初始原料制备磷酸三钙(TCP)和磷酸四钙(TTCP).研究了当代PCP/TTCP(物质的量)配比为1:1时,不同的烧结温度对复合钙磷陶瓷的结构和晶相的影响.对烧结后的样品在模拟体液中进行了浸泡实验,监测了浸泡过程中的pH值变化,通过扫描电镜、X射线衍射分析对浸泡后试样的结构和晶相的变化进行了分析.结果表明微波烧结制备的磷酸钙生物陶瓷的主晶相是HA,其结构均匀,致密度较好.且在1200℃下微波烧结HA能稳定存在,陶瓷具有良好的表面生物活性.浸泡溶液的pH值变化幅度小(在7.40～7.72之间),接近中性.     

碳/碳复合材料表面声电沉积磷酸钙生物活性涂层过程建模

声电沉积是一种非线性涂层制备生物活性磷酸钙的新方法,然而目前关于该方法的机理还不清楚。文章采用声电沉积法在C/C表面制备了磷酸钙涂层,结合实验过程,给出了声电沉积磷酸钙涂层的物理模型,并给出了沉积过程中受扩散过程控制的动力学方程,设计了相应的实验,证实阴极声电沉积生物活性钙磷速率主要由溶液中的离子向阴极表面扩散所控制。     

Glass-Ceramic Tiles Prepared by Pressing and Sintering DC Plasma-Vitrified Air Pollution Control Residues

Air pollution control (APC) residues produced from cleaning gas emissions at energy from waste (EfW) plants processing municipal solid waste are a problematic hazardous waste. In this research they have been treated using DC plasma technology and this produces an inert glass. Glass-ceramic tiles were prepared by powder pressing and sintering fritted APC residue-derived glass. Tile samples prepared with high levels of plasma treated APC residue glass had comparable physical properties to commercially available ceramics such as porcelain and monoporosa, with high bulk density (2.4 g/cm³), low water absorption (<6%) and high flexural strength (∼60 MPa).     

改善明胶生产废水污染的磷酸氢钙回收工艺

在考察明胶生产工艺、废水水质特性的基础上,提出一改进的磷酸氢钙清洁回收工艺。在浸灰工段后设一沉淀池,沉淀分离石灰沉渣,将上层饱和的氢氧化钙浸灰废液送至浸酸工序,处理浸酸废液,调pH至4.7左右,回收磷酸氢钙。而原工艺是用灰乳处理浸酸废液回收磷酸氢钙,大量饱和Ca(OH)_2浸灰废液外排,造成了难于治理的明胶生产废水高碱、高钙、高悬浮有机物污染。实验证明,该改进工艺能消耗大量的浸灰废液,有效降低明胶生产废水的高碱特性,对悬浮COD的去除效果与使用普通净水剂效果相当,且对磷钙复合肥的收率无重大影响,所排废液不再是饱和的氢氧化钙溶液,钙污染也得到一定控制,与原废水相比生化处理难度大大降低,具有显著的环境效益。     

Whisker-Reinforced Calcium Phosphate Cements

Self-setting calcium phosphate cements (CPC) consisting of hydroxyapatite (HA) and tetracalcium phosphate were reinforced with various amounts of hydrothermally synthesized HA whiskers with an aspect ratio of 10. Flexural strength (σ_b) and work of fracture (γ_wof) were calculated by four-point bending tests, and fracture surfaces were analyzed by scanning electron microscopy (SEM). σ_b and γ_wof of the CPCs that were reinforced with 30 vol% HA whiskers increased by 60% to 7.4 MPa and by 122% to 102 J/m², respectively. SEM analyses reveal that this increase could be correlated to energy-dissipating processes (e.g., whisker pull-out) at the crack tip.     

补偿法生产饲料级磷酸氢钙

用约1／4(以P2O5计)磷矿粉，与约3／4(以P2O5)二水法磷酸进行反应，以补偿脱氟过程中损失的磷，即进入肥钙中的磷；同时，采用(新技术)添加有机复合助剂——促使补偿反应磷矿粉分解转化完全；提高脱氟效果即磷收率；优化湿法磷酸生产系统各项工艺指标；可降低综合生产成本1／4。     

电石渣制备硫酸钙工艺探讨

将经过预处理后的电石渣加水成浆,与一定浓度的硫酸混合搅拌下进行反应,研究制备硫酸钙的工艺条件。通过正交实验法考察了电石渣料浆浓度、加入硫酸浓度、反应终点pH值和反应时间四个因素及各因素的不同水平对制备过程的影响。试验结果表明,当电石渣料浆浓度为25%、加入硫酸浓度为1.0m o l/L、反应终点pH值控制在6,反应时间为3h时可制备得到含量为96%以上的硫酸钙产品。     

Preparation of High-Strength Calcium Phosphate Glass-Ceramics by Unidirectional Crystallization

Unidirectionally crystallized CaO-P₂O₅ glass-ceramics were produced by reheating glass rods between 450° and 580°C (glass transition temperature ∼500°C) under a temperature gradient of 30°C/cm. These glass-ceramics exhibit high bending strength (∼650MN/m²) and toughness. Sample preparation is described and compared with conventional unidirectional solidification of melts. The characteristic mechanical properties are discussed in terms of the texture of the glass-ceramics.     

磷酸钙骨水泥的研究进展

磷酸钙骨水泥(CPC)是一种新型的自固型、非陶瓷型骨水泥,具有良好的生物相容性和骨传导性,有望成为新一代骨替代材料。本文就其固化行为、改性研究、临床应用研究几个方面对CPC综述如下。     

Reinforcement of Calcium Phosphate Cement by Bio-Mineralized Carbon Nanotube

Bio-mineralized carbon natotubes (CNTs) were prepared by soaking carboxyl functionalized CNTs in a simulating body fluid (SBF). A uniform hydroxyapatite layer was precipitated on the outer walls of CNTs after 7 days of soaking. The results showed that, by addition of the as-received CNTs and bio-mineralized CNTs, the compressive strength of the calcium phosphate cement (CPC) increased by 24% and 120%, respectively. The modified interfacial bonding between the bio-mineralized CNTs and CPC accounted for the significant improvement in the mechanical property by addition of the bio-mineralized CNTs as compared with the as-received CNTs.     

溶胶-凝胶制备Li2O-Al2O3-SiO2微晶玻璃的研究进展

Li2OAl2O3SiO2系统微晶玻璃由于其膨胀系数低,耐高温及抗热冲击性等优异性能而受到广泛重视。本文主要介绍了溶胶凝胶工艺原理、制备过程,及在Li2OAl2O3SiO2系微晶玻璃上的应用,最后简述了Li2OAl2O3SiO2系微晶玻璃的应用现状。     

Macrochanneled Tetragonal Zirconia Polycrystals Coated by a Calcium Phosphate Layer

A coextrusion process was used to fabricate three-directionally macrochanneled tetragonal zirconia polycrystals (TZP) with a calcium phosphate coating layer. The three-directionally connected structure was built by a unique alignment and a lamination of the TZP surrounded by calcium phosphate and carbon black filaments. After a thermal treatment (binder burnout and sintering), a 52 vol% array of 290 μm, three-directionally connected macrochannels, which were clad on the inside with bioactive calcium phosphate, had formed on the sintered TZP body. For a comparison, porous calcium phosphate with a similar structure was also fabricated. The compressive strength (96 MPa) of the three-directionally macrochanneled TZP with a bioactive calcium phosphate layer was much higher than that (24 MPa) of the three-directionally macrochanneled calcium phosphate.     

Tunable Enzyme-Assisted Mineralization of Apatitic Calcium Phosphate by Homogeneous Catalysis

While it has long been mimicked by simple precipitation reactions under biologically relevant conditions, calcium phosphate biomineralization is a complex process, which is highly regulated by physicochemical factors and involves a variety of proteins and other biomolecules. Alkaline phosphatase (ALP), in particular, is a conductor of sorts, directly regulating the amount of orthophosphate ions available for mineralization. Herein, we explore enzyme-assisted mineralization in the homogeneous phase as a method for biomimetic mineralization and focus on how relevant ionic substitution types affect the obtained minerals. For this purpose, mineralization is performed over a range of enzyme substrate concentrations and fluoride concentrations at physiologically relevant conditions (pH 7.4, T = 37 °C). Refinement of X-ray diffraction data is used to study the crystallographic unit cell parameters for evidence of ionic substitution in the lattice, and infrared (IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) are used for complementary information regarding the chemical composition of the minerals. The results show the formation of substituted hydroxyapatite (HAP) after 48 h mineralization in all conditions. Interestingly, an expansion of the crystalline unit cell with an increasing concentration of the enzyme substrate is observed, with only slight changes in the particle morphology. On the contrary, by increasing the amount of fluoride, while keeping the enzyme substrate concentration unchanged, a contraction of the crystalline unit cell and the formation of elongated, well-crystallized rods are observed. Complementary IR and XPS data indicate that these trends are explained by the incorporation of substituted ions, namely CO₃²⁻ and F⁻, in the HAP lattice at different positions.     

直接络合滴定法测定磷矿石中的钙

本文报导了ＥＤＴＡ直接络合滴定磷矿石中钙的分析方法。本文对磷矿石中常见离子作干扰实验，证明用ＴＥＡ－淀粉可掩蔽之。本试验用王水溶解试样，溶液在ｐＨ＞１２．５的碱性介质中，钙黄绿素－百里香酚酞与Ｃａ２＋形成绿色荧光络合物。用ＥＤＴＡ滴定至绿色荧光消失为终点，已用于标准物质及实际矿样分析。本法简便快速，结果可靠。     

Preparation of Void-Free Calcium Phosphate Glass-Ceramics

Voids frequently form on crystallization of calcium phosphate glasses because of the density difference between the original glass and the resulting glass-ceramic. However, the calcium phosphate glass-ceramic with a composition of 40CaO · 50P₂O₅· 10Al₂O₃ (mol%) has a density nearly equal to that of the original glass; this is caused by the formation of AlPO₄, which has a lower density than Ca(PO₃)₂. The glass-ceramic, being void-free, shows improved mechanical properties.     

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。     

Nanograined Ferroelectric Ceramics Prepared by High-Pressure Densification Technique

For the first time, nanograined Pb_{1−1.5 x} La _x TiO₃ ferroelectric ceramics, with x =0.2, were produced by a process based on a high-pressure densification technique (HPD) that eliminates the need of high-temperature sintering. Our results showed the production of workable dense ceramics with average grain size around 100 nm and free from secondary phase. Regarding the dielectric measurements, the samples showed satisfactory dielectric losses as well as remarkable diffusivity in the dielectric curves. Moreover, ferroelectric hysteresis measurements showed that samples produced by the HPD technique can stand high electric fields necessary to switch the polarization and thus to induce piezoelectric activity. Our results demonstrated clearly the viability of the proposed method to produce nanograined ferroelectric bulk ceramics, then opening the possibility of developing new technologies.