纯钛表面微弧氧化膜纳米压入法研究

微弧氧化是一项较新的等离子体化学-电化学成膜技术，硬度和弹性模量是膜的基本微区力学性能。采用交流微弧氧化方法的铝酸盐溶液中在TA2纯钛表面制备出较厚的氧化膜，利用纳米压入法测定了膜的硬度和弹性膜量，并探讨了微弧放电对氧化膜相组成和性能的影响。研究结果表明：膜的显微硬度和弹性模量分布有相似的变化规律，从膜表层到膜内部，硬度和弹性模量逐渐增加，并在内层膜达到最大值，分别为9.78GPa和176GPa，比钛基体高的多；膜不同浓度处TiO2金红石和TiAl2O5相的相对含量变化决定了硬度和弹性模量的分布。     

Formation of BaTiO3 coatings on titanium by microarc oxidation method

Barium titanate layers on a titanium surface have been formed with using of microarc oxidation (MAO) method. The formation process was carried out in the aqueous electrolyte containing barium ions. The formation conditions, composition and anomalous properties of surface layers obtained are discussed. Based upon the experimental results the mechanism of metal/dielectric/metal (MDM) structure formation is proposed.     

纯钛表面HA/BG生物复合涂层的组织结构研究

通过高温熔烧法在工业纯钛ＴＡ３表面制备出不同羟基磷灰石含量的羟基磷灰石与生物玻璃的复合涂层（简称ＨＡ／ＢＧ）,对复合涂层的微观组织结构进行了研究,结果表明,所制生物玻璃的高温处理的过程中会析出六方柱状的ＨＡ晶体,复合涂层具有粗糙表面,存在很多开放性气孔,随着ＨＡ原始含量的增加,复合涂层的致密度明显降低,而复合涂 ＨＡ相的衍射峰强度变化不大。     

An electrodeposition method of calcium phosphate coatings on titanium alloy

Calcium phosphates coatings were deposited onto titanium alloy discs via en electrodeposition method. Titanium alloy discs were blasted with calcium phosphate particles, then etched in a mixture of nitric and fluoric acids and rinsed in demineralized water. The titanium alloy disc (cathode) and platinum mesh (anode) were immersed in a supersaturated calcium phosphate electrolyte buffered at pH 7.4 and connected to a current generator. The microstructure, chemical composition and crystallinity of the electrodeposited coatings were studied as function of time 10–120 min, temperature 25–80°C, current density 8–120 mA/cm², magnesium and hydrogen carbonate amounts (0.1–1 mM). Uniform calcium phosphate coatings were obtained in 30 min but coating thickness increased with deposition time. Raising the temperature of electrolyte resulted in more uniform coatings as ionic mobility increased. Low current density was preferable due to hydrogen gas evolving at the cathode, which disturbed the deposition of calcium phosphate crystals on titanium. The amounts of magnesium and hydrogen carbonate ions affected both the homogeneity and morphology of the coatings. This study showed that the electrodeposition method is efficient for coating titanium with osteoconductive calcium phosphate layers.     

3D打印纯钛骨支架表面掺银介孔生物活性玻璃涂层的性能研究EI北大核心CSCD

术后感染是临床上常见且最具挑战性的问题之一,开发新型抗菌涂层是解决该问题的有效策略,具有重要的科学及社会意义。在3D打印多孔钛骨支架表面制备了具有抗菌功能的生物活性涂层,研究发现,银(Ag)以单质的形式存在于介孔生物玻璃(MBG)涂层之中,随着Ag含量的增加(0%,0.5%,1%,1.5%,摩尔分数),介孔涂层的比表面积从377.6 m^(2)/g下降到363.35 m^(2)/g。体外矿化结果表明,随着Ag含量的增加,磷灰石诱导能力略微下降。抗菌实验表明,银的添加显著提高了支架的抗菌性能。添加少量的银(0.5%)即可达到100%的抗菌率。支架与MC3T3-E1细胞共培养的实验结果表明,Ag掺杂的MBG涂层具有良好细胞相容性,且添加少量银能促进MC3T3-E1细胞增殖。使用一种简单的浸渍提拉法将掺Ag的MBG涂层应用于具有复杂的多孔结构3D打印钛支架上,使得支架的矿化性能、杀菌性能以及细胞相容性显著提高。本研究为进一步开发多功能骨植入支架提供了新思路。     

Nano-Ag-loaded hydroxyapatite coatings on titanium surfaces by electrochemical deposition

Hydroxyapatite (HA) coatings on titanium (Ti) substrates have attracted much attention owing to the combination of good mechanical properties of Ti and superior biocompatibility of HA. Incorporating silver (Ag) into HA coatings is an effective method to impart the coatings with antibacterial properties. However, the uniform distribution of Ag is still a challenge and Ag particles in the coatings are easy to agglomerate, which in turn affects the applications of the coatings. In this study, we employed pulsed electrochemical deposition to co-deposit HA and Ag simultaneously, which realized the uniform distribution of Ag particles in the coatings. This method was based on the use of a well-designed electrolyte containing Ag ions, calcium ions and l-cysteine, in which cysteine acted as the coordination agent to stabilize Ag ions. The antibacterial and cell culture tests were used to evaluate the antibacterial properties and biocompatibility of HA/Ag composite coatings, respectively. The results indicated the as-prepared coatings had good antibacterial properties and biocompatibility. However, an appropriate silver content should be chosen to balance the biocompatibility and antibacterial properties. Heat treatments promoted the adhesive strength and enhanced the biocompatibility without sacrificing the antibacterial properties of the HA/Ag coatings. In summary, this study provided an alternative method to prepare bioactive surfaces with bactericidal ability for biomedical devices.     

Osteoblastic cell response on high-rough titanium coatings by cold spray

Highly rough and porous commercially pure titanium coatings have been directly produced for first time by the cold spray technology, which is a promising technology in front of the vacuum plasma spray for oxygen sensitive materials. The wettability properties as well as the biocompatibility evaluation have been compared to a simply sand blasted Ti6Al4V alloy substrate. Surface topographies were analysed using confocal microscopy. Next, osteoblast morphology (Phalloidin staining), proliferation (MTS assay), and differentiation (alkaline phosphatase activity) were examined along 1, 7 and 14 days of cell culture on the different surfaces. Finally, mineralization by alizarin red staining was quantified at 28 days of cell culture. The contact angle values showed an increased hydrophilic behaviour on the as-sprayed surface with a good correlation to the biological response. A higher cell viability, proliferation and differentiation were obtained for highly rough commercial pure titanium coatings in comparison with sand blasted substrates. Cell morphology was similar in all coatings tested; at 14 days both samples showed extended filopodia. A higher amount of calcium-rich deposits was detected on highly rough surfaces. In summary, in-vitro results showed an increase of biological properties when surface roughness increases.

Open image in new window

     

Tissue reaction to bone plates made of pure titanium: a prospective,quantitative clinical study

In 54 patients fractures of the long bones were stabilized with limited-contact dynamic compression plates (LC-DCP) made of titanium. The implant surfaces were anodized to an interference colour of gold. The surface morphology effects the tissue response to the implant and was therefore examined. At implant retrieval, about 18 months post operatively (range 11 to 27), samples of the soft tissue layer covering the plate were excised and analysed by histomorphometrical means. The aim was to study the soft tissue reactions at the implant site and further to correlate it to the clinical symptoms of the patients. At retrieval the plates were covered by a connective tissue layer of 2 mm thickness on average. In patients with local pain a comparatively significant higher number of round cells (p=0.001) and macrophages (p=0.01) was found. This is consistent with a chronic granulomatous inflammatory reaction. The localized tissue discoloration observed in about half of the patients was confirmed as being due to titanium, but it was not the focus of a cellular reaction and was not correlated with pain. In general the implant showed good biocompatibility with excellent or good clinical results in 96% of patients.     

High speed titanium coatings by supersonic laser deposition

The importance of metal coating technologies drives the continuous improvement of metal deposition techniques for application in a wide range of industrial sectors. This work presents the foundations of a new process technology for the deposition of titanium coatings on steel tube substrates using supersonic powder streams and impact site laser heating, known as Supersonic Laser Deposition (SLD). Metallic deposits are obtained under appropriate impact conditions without the need for exceeding the melting point of the deposited material or substrate leading to improved coating quality. Details of the experimental approach are presented along with the general characteristics of the titanium coating produced using this novel coatings method.     

Ion-plated titanium carbide coatings

A new development in the field of coatings is the reactive ion-plating process. In this process, metal evaporated from a source reacts with an atmosphere of mixed gases. The reaction can take place in the gas phase before the material deposits, or it can take place on the substrate. The stoichiometry of the reaction can be controlled by adjusting at least one of several process parameters. This technique allows the formation of carbides, nitrides, oxides and other materials and provides a method of controlling the stoichiometry of the deposited material. The ability of the process to provide graded stoichiometry through a coating layer has made possible the application of adherent coatings to difficult-to-coat substrates. This prevents, for instance, a sharp boundary zone between materials which have greatly differing thermal coefficients of expansion. The dependence of the coating composition upon the deposition parameters of gas pressure, substrate voltage and evaporation rates from the source is discussed. The application of the technique in the coating of titanium and mild-steel substrates with titanium carbide is discussed. Photomicrographs and hardness data for the deposited films are presented.     

Formation of carbonitride coatings on titanium by contact and noncontact methods

We study the procedures of thermodiffusion carbonitriding of titanium. It is shown that carbonitriding can be realized in the α-region of titanium and that it is possible to affect the surface quality of the coating and its properties by optimizing the temperature, time, and gas-dynamic parameters of carbonitriding and choosing the proper procedure of carbonitriding. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 44, No. 3, pp. 43–49, May–June, 2008.     

Antibacterial hydroxyapatite coatings on titanium dental implants

Titanium and its alloys are often used as substrates for dental implants due to their excellent mechanical properties and good biocompatibility. However, their ability to bind to neighboring bone is limited due to the lack of biological activity. At the same time, they show poor antibacterial ability which can easily cause bacterial infection and chronic inflammation, eventually resulting in implant failure. The preparation of composite hydroxyapatite coatings with antibacterial ability can effectively figure out these concerns. In this review, the research status and development trends of antibacterial hydroxyapatite coatings constructed on titanium and its alloys are analyzed and reviewed. This review may provide valuable reference for the preparation and application of high-performance and multi-functional dental implant coatings in the future.     

Sol-gel derived hydroxyapatite coatings on titanium substrate

Biomaterials, in particular those used for orthopaedic prostheses, consist of a metallic substrate, exhibiting excellent mechanical properties, coated with a ceramic layer, which guarantees resistance to the corrosion and an elevated bioactivity. In this paper the preparation of sol-gel films of hydroxyapatite, HA (Ca₁₀(PO₄)₆(OH)₂), on titanium substrate is described. The samples were obtained through the dip-coating method, starting from a colloidal suspension of hydroxyapatite. In order to increase the adhesion between the HA film and the metallic substrate, the same substrate has been preliminarily coated either with titanium oxide, TiO₂ (in the anatase or rutile phase), or calcium titanate, CaTiO₃ (perovskite). Also these latter films have been deposited from a sol-gel solution. The characterization of the films through XRD, SEM, and AFM gave good results for the crystallinity of the deposited HA; for what concerns the sample morphology, the films turned out to be homogeneous and crack-free.     

Tribological properties of carbonitride coatings formed on titanium by thermodiffusion carbonitriding

We have studied the tribological properties of VT14 titanium alloy with carbonitride coatings formed by the contact and noncontact method and binary (oxide and nitride) coatings. In the case of the contact method, specimens are saturated in a graphite backfill, and in the case of the noncontact method, specimens are located above it. We have investigated the wear resistance of a “titanium disk–bronze block” friction pair in AMH-10 hydraulic fluid under a load to 3 MPa on a friction path to 15 km. It has been established that coatings based on ternary interstitial compounds (titanium carbonitrides) provide a higher wear resistance than that of coatings based on binary interstitial compounds (titanium nitrides and oxides).     

Tribotechnical properties of coatings on titanium alloys

We compare the antifriction properties of different types of coatings on titanium alloys under conditions of boundary friction as applied to parts of the hydraulic cylinders of an aircraft. We show that gasthermal titanium carbide coatings cladded with nickel and with both copper and nickel have better antifriction characteristics than ones obtained by chrome electroplating, nickel chemoplating, thermooxidation, anodization, etc. Kiev International University of Civil Aviation; J.S.S.T.C. “Antonov,” Kiev. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 34, No. 2, pp. 55–62, March–April, 1998.     

Microstructural studies and wear assessments of Ti/TiC surface composite coatings on commercial pure Ti produced by titanium cored wires and TIG process

Tungsten Inert Gas (TIG) process and titanium cored wires filled with micro size TiC particles were employed to produce surface composite coatings on commercial pure Ti substrate for wear resistance improvement. Wire drawing process was utilized to produce several cored wires from titanium strips and titanium carbide powders. Subsequently, these cored wires were melted and coated on commercial pure Ti using TIG process. This procedure was repeated at different current intensities and welding travel speeds. Composite coating tracks were found to be affected by TIG heat input. The microstructural studies using optical and scanning electron microscopy supported by X-ray diffraction showed that the surface composite coatings consisted of α′-Ti, spherical and dendritic TiC particles. Also, greater volume fractions of TiC particles in the coatings were found at lower heat input. A maximum microhardness value of about 1100 HV was measured which is more than 7 times higher than the substrate material. Pin-on-disk wear tests exhibited a better performance of the surface composite coatings than the untreated material which was attributed to the presence of TiC particles in the microstructure.     

Characterization of plasma nitrided pure titanium by X-ray absorption spectroscopy

To date, the exact nature of the plasma nitriding mechanism and the role of energetic particle bombardment are not well understood. The purpose of this work has been to obtain a more detailed knowledge about the evolution of the plasma nitrided surface layer as a function of the energy of the bombarding particles. Nitrided layers were produced at the surface of pure titanium specimens at various flux energies by Intensified Plasma-Assisted Processing (IPAP), a triode plasma technique developed in our laboratory. X-ray Absorption Near Edge Structure (XANES) spectroscopy and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy were used to characterize the local structure of the titanium nitride layers. Cross sections of the processed specimens were studied by Auger electron spectroscopy and electron microscopy. The results showed that increasing flux energy promotes the formation of a well-ordered TiN layer at the surface. Low flux energies produce significantly lower fractions of the TiN phase at the surface, as well as thinner nitrided layers. A structural model was suggested and quantitatively tested based on the XANES and EXAFS measurements.