Comparison of Selective Laser Melted Titanium and Magnesium Implants Coated with PCL

Degradable implant material for bone remodeling that corresponds to the physiological stability of bone has still not been developed. Promising degradable materials with good mechanical properties are magnesium and magnesium alloys. However, excessive gas production due to corrosion can lower the biocompatibility. In the present study we used the polymer coating polycaprolactone (PCL), intended to lower the corrosion rate of magnesium. Additionally, improvement of implant geometry can increase bone remodeling. Porous structures are known to support vessel ingrowth and thus increase osseointegration. With the selective laser melting (SLM) process, defined open porous structures can be created. Recently, highly reactive magnesium has also been processed by SLM. We performed studies with a flat magnesium layer and with porous magnesium implants coated with polymers. The SLM produced magnesium was compared with the titanium alloy TiAl6V4, as titanium is already established for the SLM-process. For testing the biocompatibility, we used primary murine osteoblasts. Results showed a reduced corrosion rate and good biocompatibility of the SLM produced magnesium with PCL coating.     

医用钛合金耐蚀性涂层的研究进展

介绍了医用钛合金的应用前景,分析了其腐蚀机理,并简述了新型医用钛合金及其表面耐蚀性涂层的研究进展.通过加入不同含量的Mo、Nb、Pa、Zr、Ta等元素生成的各种耐蚀性涂层可以改善钛合金的耐蚀性能.     

Preparation and Characterization of Lanthanum-Incorporated Hydroxyapatite Coatings on Titanium Substrates

Titanium (Ti) has been widely used in clinical applications for its excellent biocompatibility and mechanical properties. However, the bioinertness of the surface of Ti has motivated researchers to improve the physicochemical and biological properties of the implants through various surface modifications, such as coatings. For this purpose, we prepared a novel bioactive material, a lanthanum-incorporated hydroxyapatite (La-HA) coating, using a dip-coating technique with a La-HA sol along with post-heat treatment. The XRD, FTIR and EDX results presented in this paper confirmed that lanthanum was successfully incorporated into the structure of HA. The La-HA coating was composed of rod-like particles which densely compacted together without microcracks. The results of the interfacial shear strength test indicated that the incorporation of lanthanum increased the bonding strength of the HA coating. The mass loss ratios under acidic conditions (pH = 5.5) suggested that the La-HA coatings have better acid resistance. The cytocompatibility of the La-HA coating was also revealed by the relative activity of alkaline phosphatase, cellular morphology and cell proliferation assay in vitro. The present study suggested that La-HA coated on Ti has promising potential for applications in the development of a new type of bioactive coating for metal implants.     

温度对化学镀锡层形貌和耐蚀性的影响

对不同温度下制备的化学镀锡层进行了电化学腐蚀试验。使用电化学工作站测试了交流阻抗谱,研究了温度对化学镀锡层形貌和耐蚀性的影响。结果表明:Nyquist图显示不同温度下所得化学镀锡层的电化学阻抗谱都呈现出简单的容抗弧特征,随着温度从40℃升高到80℃,容抗弧半径总体上先增大后减小;Bode图显示不同温度下所得化学镀锡层的相位角与频率之间的关系曲线形状相似,在测试频率范围内都只出现一个相角峰。温度为60℃时制备的化学镀锡层表面块状颗粒的尺寸和分布最均匀,容抗弧半径最大,并且在较宽频率范围内的相位角都接近70°,表现出较好的耐蚀性。     

氧化铝陶瓷表面化学气相沉积钛涂层的制备及性能

利用卤化物还原原理,以Ti粉和I2粉为反应原料,通过化学气相沉积的方法在Al2O3陶瓷基体上制备了金属Ti涂层。考察了原料配比、加热温度及保温时间等工艺参数对涂层沉积的影响。通过X射线衍射仪分析了涂层的物相组成。利用扫描电子显微镜及能谱仪对涂层的微观组织形貌及成分进行了分析。采用座滴法考察铜与沉积了涂层的氧化铝陶瓷间的润湿性。研究结果表明,化学气相沉积法在氧化铝陶瓷表面制备Ti涂层的适宜工艺参数为:Ti与I2的质量比=1∶3,沉积温度为1 100℃,沉积时间为60min。所获得的Ti涂层纯度较高,具有明显的(110)晶面择优取向性,涂层与陶瓷结合良好。铜与涂层间的润湿角在1 113℃时为57°。     

电化学沉积法制备Cu-纳米SiO_2复合镀层及其性能的研究

利用电化学沉积法制备以纳米SiO_2微粒为增强相的Cu-纳米SiO_2复合镀层。研究发现:Cu-纳米SiO_2复合镀层的形貌特征不同于纯铜镀层的,其性能较好。增强相纳米SiO_2微粒引起形核增殖、结晶细化,同时形成弥散强化,致使Cu-纳米SiO_2复合镀层的形貌特征不同,性能得以改善。随着镀液中纳米SiO_2微粒的质量浓度的增加,Cu-纳米SiO_2复合镀层的显微硬度先升高后降低,体积磨损率先减小后增大。当镀液中纳米SiO_2微粒的质量浓度为35g/L时,Cu-纳米SiO_2复合镀层的显微硬度最高,接近1 500 MPa,约为纯铜镀层的1.46倍;体积磨损率最低,为6.59×10-5 mm3/(N·m),比纯铜镀层的降低约35.4%。     

纯钛表面微量元素协同掺杂仿生复合涂层的制备与表征

以添加多肽分子和微量元素的改良模拟体液为介质,采用湿化学工艺在碱–热处理的医用钛金属表面快速沉积三元微量元素协同掺杂磷酸钙涂层。测试了试样表面及断面的形貌、相组成以及元素分布。结果表明,在60℃或90℃的改良模拟体液中浸泡30 min后,钛金属表面出现无机矿物纳米晶粒成核,在浸泡4 h内形成连续、致密的由微量元素硅、锶...     

搅拌时间对水合碳酸镁形貌和组成的影响

通过共沉淀法,研究了Mg(NO3)2.6H2O和K2CO3生成水合碳酸镁的形貌和组成随反应初始溶液搅拌时间的变化规律。结果发现,当反应初始溶液的搅拌时间在1~8 min变化时,可使产物针状水合碳酸镁的直径控制在0.5~23μm,长度介于2~200μm;通过对产物组成的红外光谱和热重分析,发现当搅拌时间在1~20 min变化时,所得产物MgCO3.xH2O(1相似文献   

Design-Expert软件辅助内墙乳胶漆配方设计及优化的研究

采用Design-Expert软件中Mixture的试验设计方法对内墙乳胶漆PVC为65%～70%的配方进行辅助设计及优化。研究了配方中各主要组分对涂料性能的影响,建立了配方中各主要组分与涂膜对比率的定量关系模型,并通过试验对该模型进行验证,进而利用该模型以涂膜对比率为优化目标进行配方的优化。     

基于BP-PID温控系统优化Cu-SiO_2复合镀层的形貌与性能

采用单因素试验法,考察了温度对Cu-SiO_2复合镀层的形貌、显微硬度和耐磨性的影响。以得到的影响规律为依据,设计了一种基于BP-PID的温控系统。该温控系统由控制器实时采集镀液温度,根据预设值与实测值的偏差,通过BP-PID算法输出控制信号,实现精准调控镀液温度,优化Cu-SiO_2复合镀层的形貌与性能。     

MgO对阿利特-硫铝酸锶钙水泥组成、结构和性能的影响

利用X射线衍射、扫描电子显微镜、能谱和岩相分析研究了MgO对阿利特–硫铝酸锶钙水泥矿物组成、结构和性能的影响。结果表明:当MgO含量为1%～5%时,阿利特–硫铝酸锶钙水泥早期强度明显提高;MgO在水泥中的最佳含量为2%,在最佳掺量条件下,其3 d和28 d强度分别为64.3 MPa和103.6 MPa;适量的MgO能够促进硫铝酸锶钙矿物(0.5CaO.2.5SrO.3Al2O3.CaSO4,C1.5Sr2.5A3 S)的形成,但当MgO含量过高时,对C1.5Sr2.5A3 S的形成产生阻碍作用;MgO能促进阿利特矿物的形成,有利于水泥力学性能的提高;与硅酸盐水泥相比较,阿利特–硫铝酸锶钙水泥中能够固溶较多的MgO,使高镁原料的利用成为可能。     

镀液组成对硅钢表面高硅涂层形貌与性能的影响

在硅钢表面复合电镀高硅涂层,再通过扩散退火制备高硅电工钢。采用正交试验优化得到镀液组成为:FeCl_2·4H_2O 350g/L,硅粒子30g/L,KI 3g/L。实验结果表明:pH值对涂层表面裂纹有影响,当pH值为1.3时涂层表面没有裂纹,其中硅的质量分数为29.84%。1 000℃下扩散退火3h,样品的铁损P2/1k从4.49W/kg降到3.64W/kg,饱和磁感应强度B8从1.67T回升到1.79T。     

处理时间和溶液条件对等离子喷涂钛涂层诱导磷灰石生长的影响

将真空等离子喷涂的钛涂层在40℃的NaO的浓度为5mol/dm^3溶液中处理2－24h,随后在3种模拟生理溶液中浸泡,考察在碱溶液中处理时间和模拟生理溶液（组成和浓度）对涂层诱导磷灰石的形貌,结构和组成的影响,结果表明,随着涂层在碱溶液中处理时间的延长,涂层表面的网状结构愈加明显;处理时间少于8h,Mg^2 的溶液中生长的磷灰石为片状,其（002）晶面取向生长,在含CO^2 3,Mg^2 的溶液中生长的磷灰石为球状团聚体,并含有CO^2-3,为羟基磷酸磷灰石,在保持模拟生理溶液组成不变,提高溶液中离子浓度的条件下,活性钛涂层诱导磷灰石的形貌组成不变,但可以缩短磷灰石的诱导期,因此,控制钛涂层在碱溶液中处理时间和模拟生理溶液条件可以在钛涂层表面制备类骨磷灰石。     

Functional gradient coating of alumina on net shaped zirconia implant: Improved strength,aging resistance,and role of residual stress

Aging of zirconia in vivo has been widely discussed as a potential cause of implant degradation over time. Hydrothermal degradation is sensitive to composition, process conditions, and microstructure leading to an emphasis on secondary phases, and grain boundary engineering for aging resistance. However, surface coatings, resultant residual stress, and associated physical constraint for phase stabilization are insufficiently explored. Herein a novel ceramic dough processing facilitated the formation of a functional gradient alumina coating (20–50 µm) below the critical thickness, on net-shaped green zirconia dental implant while preserving the fine machined threads. Residual stress (~ ?0.8 GPa) after sintering improved the characteristic strength by ~ 45% with a simultaneous contribution to profound phase preservation after in vitro aging. Thus, the compositional gradient coating on green zirconia components using alumina-based slurries is a facile surface modification technique to inhibit moisture-induced aging.     

Synergistic effects of surface grafting with heparin and addition of poly(d,l-lactide) microparticles on properties of poly(l-lactide) single crystals scaffolds

Mixtures of heparin grafted poly(l- lactide) single crystals (Hep-PLLA_sc) and poly(d ,l- lactide) (PDLLA) microparticles are used for assembling hydrophilic and cytocompatible three-dimensional tissue engineering scaffolds simply by compression molding/salt leaching technique. PLLA is grafted with heparin to promote its surface cytocompatability, while PDLLA is added to reinforce the scaffolds. PLLA_sc are aminolyzed with tetraethylenepentamine (13-atom spacer) to generate sterically accessible amino groups at the surface allowing the covalent attachment of heparin by aqueous carbodiimide chemistry. Morphological and compressive strength studies manifest the integrity and compactness of scaffolds. Toluidine blue assay assures the consistency of heparin distribution throughout the scaffolds, which is in contrary to the conventional grafting reactions by immersing the scaffold in heparin solution. The scaffolds applicability is examined by fibroblast cells seeding experiments. Contrary to pristine scaffolds, Hep-PLLA_sc scaffolds display a hydrophilic and cytocompatible interface for cell adhesion, spreading, growth, and migration. Therefore, combining presurface grafted PLLA_sc with PDLLA microparticles could offer durable scaffolds exhibiting bioactive interface and controllable spatial distribution of the grafted biomacromolecules. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47797.     

铸铝电化学沉积陶瓷覆膜的成分、形貌、结构及成膜机理分析

采用电子能谱 (EDS)、X射线衍射 (XRD)、扫描电镜 (SEM )等现代表面分析方法对铸铝在有机羧酸混合体系中电化学沉积陶瓷覆膜的成分、结构及形貌进行了详细的研究 ,并对类陶瓷膜层的成膜过程及机理进行了初步讨论。结果表明 ,膜层组成元素为氧、铝、硅、磷、硫和碳。主要组成物为铝的氧化物、氢氧化物及它们的水合物 ,同时还有少量含磷、硫、碳的复杂化合物。SEM分析表明 ,膜层由大量直径 0 .1～ 0 .3μm的圆球状颗粒沉积而成。沉积膜可分为紧密层和疏松层。紧密层与基体金属结合牢固 ,且紧密层中存在大量纳米尺寸的微裂纹和颗粒。由此提出在特殊的电解液和工艺条件下 ,铸铝 /电解液界面首先形成阴离子凝聚物 ,由于界面化学、电化学反应和其他变化 ,凝聚层在阳极表面沉积、浓缩 ,经高温脱水和快速冷却 ,形成具有特殊结构和性能的类陶瓷膜层。     

电流密度对Ti 6Al 4V微弧氧化膜形貌和性能的影响

采用NaAlO2-Na3PO4-NaF溶液体系,研究了电流密度对Ti 6Al 4V合金微弧氧化膜厚度、生长速率、表面形貌、粗糙度、组成相以及氧化膜耐蚀性、耐磨性等影响.结果表明,(1)在试验的电流密度范围内,氧化膜的厚度随电流密度的增大呈线性增大,但氧化膜的粗糙度却几乎呈指数增大,表面质量变差;(2)在质量分数为3.5%的NaCl溶液中显示了比Ti 6Al 4V钛合金更好的耐蚀性;(3)在干摩擦条件下,氧化膜的摩擦系数高于基体的,氧化膜的磨损机制为脆性断裂.     

Effects of Silica and Titanium Oxide Particles on a Human Neural Stem Cell Line: Morphology,Mitochondrial Activity,and Gene Expression of Differentiation Markers

Several in vivo studies suggest that nanoparticles (smaller than 100 nm) have the ability to reach the brain tissue. Moreover, some nanoparticles can penetrate into the brains of murine fetuses through the placenta by intravenous administration to pregnant mice. However, it is not clear whether the penetrated nanoparticles affect neurogenesis or brain function. To evaluate its effects on neural stem cells, we assayed a human neural stem cell (hNSCs) line exposed in vitro to three types of silica particles (30 nm, 70 nm, and <44 μm) and two types of titanium oxide particles (80 nm and < 44 μm). Our results show that hNSCs aggregated and exhibited abnormal morphology when exposed to the particles at concentrations ≥ 0.1 mg/mL for 7 days. Moreover, all the particles affected the gene expression of Nestin (stem cell marker) and neurofilament heavy polypeptide (NF-H, neuron marker) at 0.1 mg/mL. In contrast, only 30-nm silica particles at 1.0 mg/mL significantly reduced mitochondrial activity. Notably, 30-nm silica particles exhibited acute membrane permeability at concentrations ≥62.5 μg/mL in 24 h. Although these concentrations are higher than the expected concentrations of nanoparticles in the brain from in vivo experiments in a short period, these thresholds may indicate the potential toxicity of accumulated particles for long-term usage or continuous exposure.     

Electrochemical composite formation of thiophene and N-methylpyrrole polymers on carbon fiber microelectrodes: Morphology,characterization by surface spectroscopy,and electrochemical impedance spectroscopy

Electrochemical composite thin film formation (∼0.6–0.7 μm) of thiophene and N-methylpyrrole on carbon fiber microelectrodes (diameter ∼7 μm) was carried out by cyclic voltammetry in order to understand and improve the surface properties and capacitance behaviour of carbon fibers. Carbon fiber microelectrodes were coated with polythiophene and N-methylpyrrole was electrografted onto the thiophene electrode. The electrocoated carbon fiber surface mophology was characterized by scanning electron microscopy and atomic force microscopy and by FTIR-reflectance spectroscopy for their composition. The effect of monomer concentration and scan number on electropolymerization has also been investigated. The impedance behaviour of composite electrodes was characterized by electrochemical impedance spectroscopy. The composite of polythiophene and poly-N-methylpyrrole exhibits better charge storage properties than polythiophene coated carbon fiber microelectrodes.     

Composition effects on elastic,thermal and corrosion properties of multiple-RE silicate (Ho1/4Er1/4Yb1/4Lu1/4)2SiO5 as a promising thermal and environmental barrier coating material

(Ho_1/4Er_1/4Yb_1/4Lu_1/4)₂SiO₅ is synthesized and characterized for the application of a promising multifunctional thermal and environmental barrier coating (TEBC) material. X-ray diffraction and scanning electron microscopy analysis indicate that a X2-type multiple-RE silicate (4RE_1/4)₂SiO₅ is formed with homogeneous distribution of the four rare earth species. Dense bulk sample exhibits excellent phase stability up to 1400 °C. Key properties including Young’s modulus, thermal conductivity and thermal expansion coefficient show interesting composition effects. Specially, (Ho_1/4Er_1/4Yb_1/4Lu_1/4)₂SiO₅ demonstrates higher elastic stiffness, lower thermal conductivity, lower thermal expansion coefficient and good resistances to molten CMAS and water vapor corrosions. These results confirm the strategy of multiple-RE engineering that may provide optimal property of advanced TEBCs.