Ti Coatings with Macropores for Improved Implant Fixation Obtained by Electrophoretic Deposition of TiH2 Stabilized Emulsions

Current implant technology focuses on enhancing the fixation between implant and surrounding tissue in order to reduce the risk of implant loosening and subsequent failing. Modifying the implant's surfaces with a macroporous metallic coating can provide a mechanical anchorage by bone ingrowth and at the same time improves the loading capacity for antibacterial drugs or bone growth stimulating agents. In this work, pure Ti coatings with spherical macropores are applied on dense Ti6Al4V substrates by electrophoretic deposition of TiH2 stabilized emulsions, followed by drying, dehydrogenation, and subsequent vacuum sintering at 850 °C. The obtained Ti coatings exhibit a porous network with an open porosity varying from 50 to 65% and a mean spherical pore size changeable from 50 to 80 µm. The morphology of the coating is easily adapted by changing the powder particle size, the emulsion droplet size, and the deposition parameters. Since the coatings are produced in the frame of optimizing implant technology, a good adhesion between the substrate and the coating is a crucial prerequisite. Measurements show that the obtained tensile adhesion strength is >29 MPa.     

电泳沉积法制备热子氧化铝绝缘层

基于Hamaker's law和静电场边界模型推导出考虑电场变化情况下沉积量与电泳条件的关系式,结合法拉第定律,使用溶液电流宏观地表征溶胶粒子沉积速率。分别改变电压和沉积时间进行电泳沉积实验,得到的沉积量与电压和时间的线性关系与本文推导出的公式一致。根据所得实验数据,在电泳条件下沉积60μm氧化铝,结果表明:涂层的表面特性主要受沉积时间影响,涂层的孔度主要由电压决定,电压40 V沉积6 s获得的热子氧化铝绝缘层性能最佳。     

水热电泳沉积功能陶瓷涂层技术的研究进展

水热电泳沉积技术结合了水热法和电泳沉积法的优点,是近几年发展起来的制备功能涂层的重要工艺技术,有着良好的应用前景.详细介绍了水热电泳沉积技术的原理、影响沉积工艺的因素,概述了水热电泳沉积动力学并总结了该技术在制备功能陶瓷涂层上的应用.指出水热电泳沉积技术是很有发展前景的涂层制备工艺;在进行水热电泳沉积应用研究的同时,应进一步开展其理论研究,探索水热电泳沉积技术的原理,建立合理的具有指导意义的理论及数学模型.     

Electrostatic Spray Deposition of Biomimetic Nanocrystalline Apatite Coatings onto Titanium

Titanium (Ti) and its alloys are widely used to manufacture orthopedic and dental implants due to their excellent mechanical properties and corrosion resistance. Although these materials are bioinert, improvement of biological properties (e.g., bone implant contact) can be obtained by the application of a coating made of nanostructured apatite. The aim of this study was to investigate the applicability of the electrostatic spray deposition (ESD) technique for the deposition of nanostructured apatite coatings onto commercially pure (cp) Ti substrates at room temperature. To that end, poorly crystalline, nano‐sized, carbonate‐apatite plate‐like particles with dimensions similar to the nanocrystals present in bone were synthesized using wet‐chemical precipitation techniques and their physicochemical properties were subsequently characterized thoroughly. The apatite suspensions were optimized for the ESD process in terms of dispersion, aggregation, and stability. Furthermore, relevant ESD processing parameters, including nozzle‐to‐substrate distance, relative humidity in the deposition chamber and deposition time were varied in order to study their effects on coating morphology. Porous films made of agglomerates of nano‐sized apatite particles of ≈50 nm were generated, demonstrating the feasibility of the ESD technique for the deposition of thin apatite coatings with a nano‐sized surface morphology onto titanium substrates. The ability of these nanocrystals to bind therapeutic agents for bone diseases and the capability of ESD to produce coating at physiological conditions makes this work a first step toward the set‐up of coatings for bone implants based on surface‐activated apatite with improved functionality.     

沉积电压对水热电泳沉积硅酸钇涂层显微结构的影响

采用水热电泳沉积法在SiC-C/C复合材料SiC内涂层表面制备了硅酸钇抗氧化外涂层,并借助X射线衍射(XRD)、扫描电子显微镜(SEM)对涂层的相组成及显微结构进行了表征.讨论了沉积电压对硅酸钇涂层沉积量及显微结构的影响,并研究了不同沉积电压下涂层沉积量与时间的关系,同时测试了涂层试样的抗氧化性能.研究结果表明,随着沉积电压的升高,涂层的沉积量有所增加,涂层的致密性和均匀性也逐渐得到改善.当电压为210V时达到最佳,继续升高沉积电压,涂层的均匀性变差,当沉积电压为240V时,涂层出现明显开裂;不同沉积电压下涂层沉积量随时间呈抛物线变化;涂层在1500℃静态空气中经过10h氧化后,失重仍然小于2%.     

化学处理制备多孔钛表面磷灰石涂层

本文中采用化学方法制备多孔钛表面磷灰石涂层。多孔钛样品经HCl H2SO4混合溶液及NaOH水溶液处理后，表面形成氧化钛及钛酸钠层。在过饱和Ca—P溶液中浸泡一段时间，磷灰石涂层沉积到多孔钛的表面。涂层由片状的垂直于金属表面的磷灰石和OCP结晶组成，不含CO3基团。涂层的Ca／P比约为1．46左右，小于羟基磷灰石的Ca／P化学计量比。涂层厚度约50μm，涂层后多孔钛的最大孔径约为150μm，可以满足临床使用要求。     

烧结TiH_2粉末制备钛合金的工艺及组织EI北大核心CSCD

以TiH2粉末为原料,通过组元球磨混合、压制成形和烧结工艺制备钛合金。用扫描电镜对球磨过程TiH2粉末的粒度、形貌变化以及烧结CP-Ti,Ti-6Al-4V合金的组织形貌进行了观察;采用热重分析方法研究了TiH2粉末脱氢的特性;用热膨胀技术研究了TiH2,TiH2-Al-V两种粉末压坯的烧结致密化特性。结果表明:TiH2粉末经过球磨后迅速变细,其粒度随球磨时间的延长而减小,粉末形貌由原来的不规则形状逐渐变为等轴状;TiH2粉末在烧结过程的脱氢将使α-Ti产生强烈收缩、同时因脱氢后获得的新鲜钛表面所发生的快速粘接而使烧结体迅速致密、得到相对密度大于99%的烧结坯体;TiH2-Al-V粉末压坯在烧结时因为伴随着合金元素的溶解而使其烧结致密特性不如纯TiH2粉末压坯的好;TiH2粉末经过成型、烧结脱氢工艺可获得典型的等轴状纯钛组织,TiH2-Al-V粉末经过相同工艺可获得典型的层片状α+β钛合金组织、且合金元素分布均匀。     

用电泳沉积方法制备LiCoO2薄膜

将LiCoO2粉末分散在异丙醇溶剂中电泳沉积,在铝箔阴极上制备出了LiCoO2薄膜.研究了pH值、悬浮液浓度、外加电压和时间等工艺参数对单位面积膜层质量的影响,初步探讨了Li-CoO2的电泳沉积机理.研究发现:悬浮液中不加HCl时,LiCoO2不能从异丙醇悬浮液中电泳沉积出来;LiCoO2的沉积量随悬浮液的pH值减小而增加,随悬浮液浓度、外加电压的增大和时间的延长呈线性增加.通过SEM分析发现,电泳沉积得到的LiCoO2薄膜不很致密,但作为锂离子电池正极材料使用是完全可以满足要求的.     

Effect of Plasma Power on the Deposition of Diamond Coatings on Pure Titanium

Diamond coatings appear to be a promising solution for the improvement of tribological behavior of titanium alloys. By means of microwave plasma assisted chemical vapor deposition (MW-PACVD), diamond coating was deposited on pure titanium using CH₄/H₂ gas mixtures under different plasma powers. Surface and interface characterization of the deposited coating under different plasma powers was carried out using SEM, grazing incidence x-ray diffraction (GIXD) and Raman spectroscopy. Adhesion of diamond coating with substrate was evaluated using an indentation tester. Results showed that adhesion of diamond coatings was not good under high plasma power, whereas the crystallinity of diamond coating was not good under low plasma power. The higher the plasma power, the larger the diamond crystal size, the less content of non-diamond carbon and the poorer the adhesion strength. During the diamond deposition, growth of TiC competed with diamond formation for the available carbon content. Relatively low plasma power inhibited TiC formation more than diamond formation. Under a high plasma power, the formation of a thick and porous TiC layer appeared to promote interfacial debonding and spallation of the diamond coating.     

Electrophoretic Depostition of Hydroxyapatite Coating

Hydroxyapatite (HAP) coatings were deposited onto titanium substrates by electrophoretic deposition(EPD) from ethanol.The results indicated that the addition of very small amount of HCl resulted in a decrease in the aging time as weel as the suspension concentration required to obtain a coating,In addition,the results revealed the existence of a critical saturated voltage (Vsat),which had significant effect on the quality of deposition ,The mean interfacial shear strenghs of HAP coatings after sintering were found to be greater than 13 MPa.     

Electrophoretic Deposition of Hydroxyapatite Coating

Hydroxyapatite (HAP) coatings were deposited onto titanium substrates by electrophoretic deposition (EPD) fromethanol. The results indicated that the addition of very small amount of HCI resulted in a decrease in the aging timeas well as the suspension concentration required to obtain a coating. In addition, the results revealed the existenceof a critical saturated voltage (Vsat), which had significant effect on the quality of deposition. The mean interfacialshear strengths of HAP coatings after sintering were found to be greater than 13 MPa.     

Mechanisms Involved in the Deposition of Coatings from Aqueous Colloidal Suspensions of Silica in an Electric Field

Although several processes have been developed to obtain ceramic coatings, many of them are complex, and expensive equipment is required. As an alternative process, in this work, electrodeposition was used to deposit silica on stainless steel substrates. The properties of commercial silica were changed by adding some chemical compounds. Potassium hydroxide was added to promote, in a controllable way, the formation of a silicate network to obtain good adherence on metallic substrates. The addition of reagents caused controlled destabilization on suspension and promoted the formation of clusters. The application of an electric field to obtain coatings allowed the orientation of charged particles and, hence, the properties of the deposited material to be modified. Electrokinetic parameters, electrical response, and GDS profiles were measured to determine the influence of electric field on the coatings.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 6, 2005, pp. 733–739.Original Russian Text Copyright © 2005 by Mendoza-Lopez, Aviles-Arellano, Perez-Robles, Manzano-Ramirez, Vorobiev, Perez-Bueno.     

钛表面电化学法制备掺锶羟基磷灰石涂层及其形貌控制

利用电化学法在钛金属基体表面沉积掺锶羟基磷灰石(SrHA)晶体涂层。通过改变电解液的成分和浓度,可控地制备出掺锶比例在0到100%之间且具有不同结晶度的SrHA涂层。其中较高沉积温度下,在低Ca、P浓度电解液中制备出由尺寸较大的六棱柱状SrHA晶体组成的涂层;而较低沉积温度下,在高Ca、P浓度电解液中制备出由尺寸较小的针状SrHA晶体组成的涂层。利用两步电沉积法制备出荆棘状SrHA涂层,其结构为较大的棒状SrHA侧面长出较小的棘状晶体,以增大SrHA涂层的比表面积。对比三种SrHA涂层在生理溶液中的锶离子释放速率,发现荆棘状SrHA涂层的锶离子释放速率最大。最后进行了3组SrHA涂层表面成骨细胞增殖的初步研究。     

电泳沉积制备氮化铝陶瓷的研究

采用电泳沉积法成功制备相对密度达到61.9%的均匀氮化铝素坯, 经无压烧结后可获得热导率为200W/(m·K)的氮化铝陶瓷. 研究表明, 以无水乙醇为溶剂、加入0.1wt%聚丙烯酸（PAA）做分散剂、pH值控制在9.7左右的悬浮液具有最佳分散性. 电泳沉积（EPD）成型比干压成型制备的预烧体孔容减小, 比湿法成型制得的预烧体大孔显著减少. 用扫描电子显微镜（SEM）对三种不同成型方法制得氮化铝陶瓷的显微结构进行了研究, 结果表明, EPD法所得氮化铝陶瓷的显微结构均匀, 晶粒尺寸5μm左右.     

纳米Al2O3电泳沉积成膜的影响因素研究

为研究电泳沉积薄膜沉积量分布特征及影响因素,对纳米Al_2O_3材料进行电泳沉积薄膜试验和仿真研究。试验过程中,对纳米Al_2O_3薄膜沉积的微观形貌、成分及沉积量与电压、沉积时间关系进行了研究;在仿真研究过程中,利用电场、流场、沉积场多场耦合技术研究分析了电场分布、流场特性、沉积时间等对电泳沉积纳米Al_2O_3薄膜的影响。结果表明:电场在阴极正、反两侧强弱分布使得正面沉积量明显大于反面,同时流场的涡流分布特征加速了粒子在阴极边缘沉积。仿真结果与试验结果吻合度较好,验证了仿真模型的有效性,为进一步研究电泳沉积流体流动特性和沉积过程提供了一种新的研究方法和手段。