Surface modification of titanium 6-aluminum 7-niobium alloy with biodegradable polymer coatings

The aim of the study is to determine the effect of long-term exposure to Ringer's solution on the physical properties of biodegradable polymer coatings on the titanium 6-aluminum 7-niobium alloy substrate. 30 day, 60 day and 90 day research periods are applied. The work is performed on a titanium 6-aluminum 7-niobium alloy modified by sandblasting and anodic oxidation. Three biodegradable polymer coatings: poly(glycolide-ϵ-caprolactone); poly(glycolide-ϵ-caprolactone-L,L-lactide) and poly(D,L-lactide-glycolide), containing ciprofloxacin are used in the study. The coatings are deposited by dip-coating method. Topography, wettability, and adhesion of the coatings are analyzed. The analysis of the test results indicates that regardless of the type of coating and the number of dips, the obtained coatings are continuous, hydrophilic, map the topography of the substrate, and slight change roughness after exposure to Ringer's solution. After three months of exposure to Ringer's solution, an increase in wettability and, at the same time, a significant decrease in adhesion is observed. The poly(D,L-lactide-glycolide) coatings are characterized by the greatest adhesion to the substrate.     

A study on hybrid bioceramic coatings of HA/poly(vinyl acetate) co-deposited electrochemically on Ti–6Al–4V alloy surface

A novel electrochemical co-deposition approach was developed to prepare hybrid bioceramic coating of hydroxyapatite (HA)/poly(vinyl acetate) on the surface of Ti–6Al–4V alloy. The aim is to improve the adhesion between the HA coating and the metal substrate. Surface characterization showed that the composition of inorganic phase in the composite bioceramic coatings was mainly HA and the content of organic phase was more than 4% (W/W). Significant surface morphology changes were observed. The shear-testing experiments indicated that the bonding strength of the hybrid coating to metal substrate was increased by as much as 3 MPa.     

Micrometer level structural and chemical evaluation of electrodeposited calcium phosphate coatings on TA6V substrate by STEM-EDXS

Hydroxyapatite (HA) coatings on titanium alloy substrates Ti6Al4V have been prepared in our laboratory by electrodeposition and hydrothermal synthesis. In this paper, the morphology, crystal size, porosity and Ca/P atomic ratio are investigated using scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), Raman microspectroscopy and X-ray energy dispersive spectroscopy (EDXS). The results obtained show that after being hydrothermally treated and calcined at high temperature, the electrodeposited brushite coating is converted into a stoichiometric hydroxyapatite having a crystal size which changes considerably from the surface to the substrate alloy. In addition, variation of the surface coating porosity as a function of the electrolyte temperature has also been carried out.     

LY12铝合金表面电火花强化层组织与性能研究

采用自制电火花强化机,以TC4合金作为电极,在空气介质中对LY12铝合金进行了表面强化。分别用扫描电镜、电子能谱分析仪与X射线衍射仪对强化层的组织、成分与结构进行了分析与研究;用显微硬度计与磨损试验机等实验设备对强化层的显微硬度与耐磨性进行了测量与分析。结果表明:强化层连续、致密,与基体之间呈冶金结合;主要由钛-铝金属间化合物和钛或铝的氮、氧化物相组成,显微硬度可达HV596;在干摩擦磨损实验条件下,强化后试样磨损体积仅为未强化试样的1/7。铝合金表面性能得到显著改善。     

Fabrication and characterization of bioactive glass coatings produced by the ion beam sputter deposition technique

Ion beam sputtering and ion beam sputtering/mixing deposition techniques were used to produce thin bioactive glass coatings on titanium substrate. It was found that as-deposited coatings were amorphous. Scanning electron microscopical examination showed that the coatings had a uniform and dense structure and that fabrication parameters affected the surface morphology of the coatings. The surface Ca/P ratio of the coatings, which varied from 5.9 to 8.6 according to semi-quantitative EDX analyses, was correlated with the fabrication condition. Depth profiling of the coatings revealed four distinct zones: the top surface, the thin coating zone, the intermixed zone of coating and substrate, and the substrate. Scratch tests showed that the coatings adhered well to the substrate.     

镍基625合金电子束熔覆TiC涂层表面改性研究

目的 采用电子束表面改性技术对Inconel 625镍基合金进行电子束表面合金化(EBSA)处理,制备性能良好的TiC涂层,提高Inconel 625镍基合金的表面性能。方法 采用不同的电子束扫描速度(80、100、120 mm/min)在Inconel 625镍基合金表面制备TiC涂层,使用扫描电镜(SEM)拍摄合金区横截面进行EDS能谱分析,使用电子背散射衍射仪(EBSD)对合金层进行EBSD表征分析,使用显微硬度仪测量EBSA后的表面硬度,使用摩擦磨损试验机(RTEC)测试表面耐磨性、生成摩擦曲线并拍摄磨损表面的三维形貌。结果 从宏观形貌上来看,在80 mm/min扫描速度下涂层成形质量最好。微观组织测试结果表明,随着扫描速度的增大,平均晶粒尺寸增大。显微硬度测试结果表明,随着扫描速度的增大,表面硬度呈现降低的趋势,但涂层表面硬度均高于基材硬度。当扫描速度为80 mm/min时,TiC强化颗粒较多分布在表面,其表面硬度最高,为457HB,与基材相比,表面硬度提高了1.936倍。耐磨性测试结果表明,当扫描速度为80 mm/min时,磨损体积和磨损率最低,分别为0.913 1 mm<...     

Nanostructured Al2O3–TiO2 coatings for high-temperature protection of titanium alloy during ablation

Plasma-sprayed nanostructured Al₂O₃–13 wt.%TiO₂ coatings were successfully fabricated on titanium alloys (Ti–6Al–4V) using as-prepared feedstock. Ablation experiments for the titanium alloy samples with or without a coating were carried out using a Metco 9MB plasma gun. The microstructure, phase constituents and mechanical properties of the titanium alloys before and after ablation were investigated by scanning electron microscope (SEM), X-ray diffractometer (XRD) and Vickers hardness tester. The surface morphologies, cross-sectional microstructure and hardness of titanium alloys with coatings are similar before and after ablation. In contrast, the microstructure and mechanical properties of the titanium alloy without coating are significantly changed after ablation. The surface coating is found to serve as a protective coating during ablation.     

Plasma Sprayed Copper-Nickel-Indium Coatings on Titanium Alloys

Copper-nickel-indium coatings were deposited on the surface of titanium alloy specimens by plasma spraying. The structure and properties of the coatings were studied thoroughly using optical and scanning electron microscopy. The mechanical behavior of the Cu-Ni-In coated titanium substrates was examined. The coating was found to decrease the tensile strength of the titanium alloy substrate. The elastic modulus and the ultimate tensile strength of the coated system were found to decrease with increasing coating thickness. The residual stresses of the coated system were also calculated.     

TiC coatings deposited onto carbon and molybdenum surfaces by electron beam evaporation

TiC coatings were deposited onto graphite and molybdenum substrates by an electron beam evaporation method. A titanium film 1000–10000 Å thick was evaporated onto the graphite substrate which was then heated at 1000 °C for 5 min to form the TiC film by an interdiffusion process. In the case of the molybdenum substrate, a double-layer film consisting of titanium and carbon (Ti/C/Mo) was prepared by evaporation and the subsequent heat treatment was performed at 700 °C or at 1000 °C for 5 min. The properties of the coatings were examined by various surface analysis techniques including Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Rutherford backscattering (RBS). The atomic ratio of carbon to titanium in these coatings was found to be 0.9. The in-depth profiles obtained by XPS examination showed that the coating prepared at 700 °C had a carbon layer between the TiC layer and the molybdenum substrate, while that prepared at 1000 °C had an Mo₂C layer between the coating and the substrate.     

The effect of electron beam fusion on the structure and properties of plasma jet sprayed nickel alloy coatings

Nickel-based alloy coatings were obtained on carbon steel (steel 3) samples by means of high-velocity pulsed plasma jet spraying of PG-10N-01 and PGAN-33 commercial powders, followed by electron beam fusion of the coating and substrate. The coated samples were studied by methods of X-ray diffraction, scanning electron microscopy, and electron-beam microprobe (energy-dispersive X-ray spectroscopy) and tested for hardness, friction wear, corrosion resistance, and adhesion. It was found that the electron beam processing leads to an almost tenfold increase in the friction wear resistance, a threefold growth in microhardness (relative to that of the substrate), and a significant increase in the resistance to corrosion in acid media. The observed increase in the working characteristics is related to changes in the phase composition, grain structure refinement, and redistribution of alloy components in the substrate and film and a decrease in porosity of the coating material.     

镍基喷焊涂层与钛合金基体界面特征的研究

考察了三种工艺制备的镍基喷焊涂层与钛合金基体结合界面的组织形貌、涂层横切面上合金元素的扩散和显微硬度的变化,分析了它们的界面特征及影响因素.结果表明:镍基喷焊涂层与基体钛合金的结合是基于合金元素扩散的冶金结合,合金元素的扩散对涂层与基体能否形成冶金结合具有决定性的影响,钛合金表面的活化处理、涂层合金重熔时液态停留时间以及喷焊后进行时效处理是影响合金元素扩散的主要因素.     

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.     

梯度结构羟基磷灰石生物活性涂层的性能

采用等离子喷涂系统在Ti6Al4V钛合金基体表面制备出真有梯度结构的羟基磷灰石生物活性梯度涂层,利用纳米硬度计等手段分析了生物活性涂层的梯度结构．结果表明：金属基体与陶瓷界面区域的弹性模量和硬度呈梯度变化;生物活性功能涂层的表面具有典型的多孔结构特征,整个涂层沿垂直基体方向从底层致密结构向表面层多孔结构过渡;涂层的成分从生物稳定性的底层至生物活性的表面层呈梯度变化,涂层表面成分为具有生物活性的羟基磷灰石．涂层的这种结构特征保持了涂层的生物活性,提高涂层与基体的结合强度（48．6MPa）。     

Highly adhesive hydroxyapatite coatings on titanium alloy formed by ion beam assisted deposition

A compact crystalline hydroxyapatite coating on Ti–6Al–4V substrate with an atomic intermixed coating/substrate interface about 27 nm in width was synthesized by ion beam assisted deposition (IBAD) and a following post-treatment. The coating after post-treatment was identified by X-ray diffraction as crystalline hydroxyapatite. The interface between coatings and substrates was studied by Auger electron spectroscopy. The adhesive strength between coatings and substrates was measured by scratch tester. The results showed that the adhesive strength of IBAD coatings is nearly twice that of ion beam sputtered coatings. The study also showed that coatings prepared by IBAD eliminated the interfacial deficiencies existing in plasma-sprayed coatings.     

Electro-spark deposition of Fe-based amorphous alloy coatings

A simple and effective surface coating technique, electro-spark deposition (ESD), has been used to produce amorphous alloy coatings. Fe-Cr-Mo-Gd-C-B amorphous alloy rods produced by copper mould casting were used as electrode to produce coatings onto 304 stainless steel substrate. Classical X-ray diffraction (XRD), glancing angle XRD (GAXRD), and scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis indicate that the coatings have an average thickness of ∼ 30 μm, show an amorphous structure, and are metallurgically bonded to the substrate. Microhardness tests showed that the coating layer has a high hardness of 1542 kg/mm², implying a much improved wear resistance on surface of stainless steels.     

Selective Laser Post-Treatment on Titanium Cold Spray Coatings

The aim of the present work is to investigate the feasibility and effects of a selective postdeposition laser treatment on titanium coatings. Commercially pure titanium grade 2 powders were deposited by means of a cold spray process on aluminum alloy AA2024-T3 sheets. The surface treatment of the coating was realized using a 220 W diode laser. The influence of heat input and dimensional features of coating layer and substrate was assessed by an experimental campaign conducted following a design of experiments approach. Optical and scanning electron microscopy analysis of the microstructure of the deposited and treated material as well as microhardness measurements showed the formation of a compact layer of titanium oxide on the coating surface and the preservation of the temper state of the aluminum substrate.     

Electrophoretic deposition of silicon-substituted hydroxyapatite/poly(ε-caprolactone) composite coatings

Silicon-substituted hydroxyapatite/poly(ε-caprolactone) composite coatings were prepared on titanium substrate by electrophoretic deposition in n-butanol and chloroform mixture. The effect of the concentration of poly(ε-caprolactone) in suspension on the morphology and the microstructure of coatings were investigated, furthermore, the thermal behavior and in vitro bioactivity were also investigated. The results show that the coarse and accidented silicon-substituted hydroxyapatite/poly(ε-caprolactone) composite coatings were obtained by electrophoretic deposition when the concentration of poly(ε-caprolactone) in suspension was 6–16 g/l. The adsorption of poly(ε-caprolactone) on the surface of Si–HA particles hinders the electrophoretic deposition of Si–HA. The shear-testing experiments indicated that the addition of poly(ε-caprolactone) in suspension is in favor of improving the bonding strength of the coatings. After immersion in simulated body fluid for 8 days, silicon-substituted hydroxyapatite/poly(ε-caprolactone) composite coatings have the ability to induce the bone-like apatite formation.     

NdFeB磁性基材化学镀Ni-Cu-P初期形核过程及机赦

为了弄清NdFeB磁性材料表面化学镀Ni-Cu-P合金初期形核过程及机制,研究了不同时间化学镀Ni-Cu-P合金层初期形核过程、形貌和组织结构特征。结果表明：初期沉积过程具有明显的择优倾向和不均匀性：Ni和Cu原子并非以单个原子的形式沉积于基体表面,而是还原后在固．液界面处形成原子团在基体表面高能量区域优先沉积形核,然...     

Structure and properties of TiC/Ti coatings fabricated on NiTi by plasma immersion ion implantation and deposition

A titanium carbide (TiC) nanostructured coating and Ti intermediate layer are fabricated on NiTi by plasma immersion ion implantation and deposition (PIII&D) to improve the surface properties. The chemical composition and structure are determined by X-ray diffraction, Auger electron spectroscopy, scanning electron microscopy, and atomic force microscopy. Nano-indentation is used to evaluate the mechanical properties of the thin film and the biological characteristics are assessed by electrochemical measurement and soaking tests in simulated body fluids. Based on the potentiodynamic polarization and Ni release data after the polarization test, the Ti/TiC nanostructure coating has better corrosion resistance compared to the NiTi substrate and there is significantly less Ni ion release from the NiTi substrate into the simulated body fluids than the uncoated NiTi alloy.     

Mechanical and corrosion properties of Al/Ti film on magnesium alloy AZ31B

Preparation of titanium film on magnesium substrate faces a challenge due to non-Fickian inter-diffusion between titanium and magnesium. Aluminum can build a bridge between titanium and magnesium. Al/Ti duplex coatings were deposited on magnesium alloy AZ31B using magnetron sputtering (MS). The low temperature diffusion bonding behavior of the Mg/Al/Ti coating was investigated through SEM and its affiliated EDS. The phase structure and critical load of the coatings were examined by means of XRD and scratch tests, respectively. The results demonstrated that the bonding strength was significantly improved after a post heat treatment (HT) at a temperature of 210°C. The diffusion mechanism of the interfaces of Mg/Al and Al/Ti in the coating was discussed based on the analysis of formation energy of vacancies and diffusion rates. The Al/Ti dual layer enhanced the corrosion resistance of the alloy. And the HT process further increased the corrosion resistance of the coated alloy. This result implies that a post HT at a lower temperature after MS is an effective approach to enhance the bonding strength and corrosion resistance of the Al/Ti film on Mg alloys.