Surface characteristics of anodized and hydrothermally treated titatnium with an increasing concentration of calcium ion

Titanium is widely used as an implant material due to its good mechanical properties and the excellent biocompatibility of the oxide film on the surface. To modify the unstable oxide surface of pure titanium, plasma electrolytic oxidation was applied in this study. The electrolyte used for anodizing was a mixture of GP (glycerophosphate disodium salt) and CA (calcium acetate). In addition, a hydrothermal treatment was performed to precipitate a calcium phosphate crystal on the titanium oxide layer for bioactivity. The effect of the CA concentration of the electrolyte on the surface of titanium was investigated, with CA concentrations at 0.1 M, 0.2 M, and 0.3 M. A high concentration of CA results in a low breakdown voltage; hence many large micropores were formed on the anodized surface. Moreover, the size of the HA crystals was more minute in proportion to the increasing concentration of CA. The crystal phase of titanium dioxide was mainly anatase, and a rutile phase was also observed. As the size and/or amount of HA crystals increased, the surface roughness increased. However, the surface roughness could be decreased by fully and uniformly covering the surface with HA crystals. The corrosion resistance in the saline solution was increased by anodic spark oxidation. In addition, it was slightly increased by a hydrothermal treatment. It is considered that a more stable and thicker titanium oxide layer is formed by anodic oxidation and a hydrothermal treatment.     

The effect of fluoride treatment on titanium treated with anodic spark oxidation

This study examined the effect of fluoride on the surface characteristics of an anodized titanium implant. Commercial pure titanium plate 20mm×10mm×2mm in size, and discs 1.5 mm thick and 1.5 mm in diameter, were used. The prepared samples were polished with #200 to #1, 000 SiC papers and were then washed sequentially with distilled water, alcohol and acetone. Anodic oxidation was performed using a regulated DC power supply in an electrolyte containing a mixture of 0.015 M DL-α-glycerophosphate disodium salt hydrate (DL-α-GP) and 0.2 M calcium acetate hydrate (CA) with an electric current density of 30mA/cm² and voltage ranging from 0 to 290 V. The specimens were divided into four groups and a fluoride treatment was carried out. Group 1 was thermally treated in a 0.05 M TiF₃ solution at 90°C, Group 2 was electrochemically treated at 150 V in a 0.05 M TiF₃ solution, Group 3 was electrochemically treated at 150 V in a 0.05 M NaF solution, and Group 4 was electrochemically treated at 150 V in a 0.05 M HF solution. A porous oxide layer containing pores 1–4 μm in size was observed on the surface treated with anodic oxidation. The diameter of the pores was higher in the protrusion areas than in the sunken areas. A significant amount of fluoride ions was released in the initial period, with small amounts being released continuously thereafter. The viability of MC3T3 cells was high when the fluoride ion concentration was 10 ppm, but decreased with further increases in the fluoride concentration. A six-week immersion test in simulated body fluid (SBF) showed dense HA crystals in the group immersed in 0.05 M TiF₃ at 90°C, which indicated good biocompatibility.     

Preparation of biocompatible structural gradient coatings on pure titanium

In order to overcome the poor osteo-inductive properties of titanium implant, some methods have been used. The efforts to improve implant biocompatibility and durability by applying a hybrid technique of composite oxidation (pre-anodic and micro-arc oxidation) and hydrothermal treatment were described. Pure titanium was used as the substrate material. An oxalic acid was used as the electrolyte for the pre-anodic oxidation. A calcium and phosphate salt solution was acted as the electrolyte of micro-arc oxidation and the common pure water was used for hydrothermal treatment. X-ray diffraction (XRD), and scanning electron microscopy (SEM) have been used to investigate the microstructure and morphology of the coatings. The results show that a compact TiO2 film can be made by pre-anodic oxidation, which is effective as chemical barriers against the in-vivo release of metal ions from the implants. A porous TiO2 coating can be produced by micro-arc oxidation on titanium plate, which is beneficial to bone tissue growth and enhancing anchorage of implant to bone. De-calcium HA can be formed on the coating using hydrothermal treatment, which is similar with the primary component of bone and has a very good osteo-inductivity.The porous gradient titania coating made by the hybrid oxidation and hydrothermal treatment should show good biocompatibility in the environment of the human body.     

Electrochemical deposition of hydroxyapatite coatings on titanium

1 Introduction Titanium implants have been used widely for various types of bone-anchored reconstructions due to their excellent corrosion resistance and mechanical properties. However, titanium exhibits poor osteoinductive properties, fortunately, which…     

HA coating on titanium with nanotubular anodized TiO2 intermediate layer via electrochemical deposition

Hydroxyapatite（HA） coating has been prepared on titanium substrate through an electrochemical deposition approach. In order to improve the bonding strength between HA coating and Ti substrate, a well oriented and uniform titanium oxide nanotube array on the surface of titanium substrate was applied by means of anodic oxidation pre-treatment. Then the calcium hydrogen phosphate（CaHPO4·2H2O, DCPD） coating, as the precursor of hydroxyapatite coating, was electrodeposited on the anodized Ti. At the initial stage of electro-deposition, the DCPD crystals, in nanometer precipitates, are anchored in and between the tubes. With increasing the deposition time, the nanometer DCPD crystals are connected together to form a continuous coating on titanium oxide nanotube array. Finally, the DCPD coating is converted into hydroxyapatite one simply by being immersed in alkaline solution.     

钛及钛合金的激光表面改性研究现状

硬度低、耐磨性能差是制约钛合金发展的关键问题,而激光表面改性处理是解决这一问题的有效途径。结合近年来激光表面改性处理的研究进展,综述了激光表面处理的影响因素,激光表面处理表层的组织、性能及缺陷控制,并指出了目前存在的问题和今后研究的重点方向。     

Preparation and properties of a cerium-containing hydroxyapatite coating on commercially pure titanium by micro-arc oxidation

A porous cerium-containing hydroxyapatite coating on commercially pure titanium was prepared by micro-arc oxidation （MAO） in an electrolytic solution containing calcium acetate, p-glycerol phosphate disodium salt pentahydrate （β-GP）, and cerium nitrate. The thickness, phase, composition morphology, and biocompatibility of the oxide coating were characterized by X-ray diffraction （XRD）, electron probe microanalysis （EPMA）, scanning electron microscopy （SEM） with energy dispersive X-ray spectrometer （EDS）, and cell culture. The thickness of the MAO film is about 15-25 ~tm, and the coating is porous and uneven, without any apparent interface to the titanium substrates. The results of XRD and EDS show that the porous coating is made up of hydroxyapatite （HA） film containing Ce. The favorable osteoblast cell affinity makes the Ce-HA film have a good biocompatibility. The Ce-HA film is expected to have significant medical applications as dental implants and artificial bone joints.     

医用钛合金及其表面活化的研究现状

医用Ti合金具有良好的力学性能、耐腐蚀性能和生物相容性,在医学临床上获得广泛应用,但是其耐磨性能和生物活性等方面仍不够理想,耐腐蚀性能也有待于进一步提高.开发具有更佳综合性能的医用钛合金,或对现有成熟医用钛合金进行表面改性是解决上述问题的有效途径.本文综述了医用钛合金的发展及其存在的问题和表面活化研究进展,并对医用Ti合金的表面活化的前景进行了展望.     

钛及钛合金表面转化膜的应用及发展

对钛及钛合金的表面转化膜处理技术进行了综述,主要包括化学氧化、阳极氧化、硅烷化、磷酸盐转化等。阐述了各种处理方法的工艺过程及其作用效果,分别指出了各种方法的优缺点。同时展望了其今后的应用及发展前景。     

粉末冶金多孔钛表面生物活化的研究

采用粉末冶金法制备了具有适合人体组织长入孔径的多孔钛,并对其进行生物活化处理.利用EPMA、SEM、XRD等研究了不同预处理方法和浸泡时间对多孔钛表面羟基磷灰石(HA)的形貌及形成速度的影响.结果表明,多孔钛的表面以及孔的内表面上均有纳米晶TiO2生成,预钙化处理能够明显提高多孔钛表面生成羟基磷灰石的速率,促进HA的形核长大,预钙化后磷含量增加明显,验证了Na2HPO4在预处理中对多孔钛的活化是有利的.     

两段式阳极氧化法制备大管径TiO2纳米管

应用电化学阳极氧化方法,在自选的电解液中,通过调节氧化电压和氧化次数制备不同管径的TiO2纳米管。其管径可分别控制在50,100和200nm左右。其中50和100nm范围的纳米管是一次氧化所制得。通过再次氧化突破了一次氧化对尺寸的限制,所制得纳米管的最大管径达到280nm。实验证实,在一定的电压范围内,通过调节阳极氧化的电压可以控制TiO2纳米管的管径大小。但是,在本实验的电解液条件下,在一次氧化过程,通过调节电压制备出的纳米管最大管径只能达到120nm。采用两次氧化能将TiO2纳米管的管径扩大到更大的尺寸,可以扩展TiO2纳米管的应用范围。     

Surface Characteristics and Indentation Deformation of Porous Anodic TiO2 Layer Before and After Hot Water Treatment

Hot water treatment was performed to modify the surface of porous TiO2 layer prepared by anodic spark oxidation technique for better biocompatibility.The oxide layer without water treatment exhibited a porous surface with few nanometer features and consisted of poorly crystallized oxides.During water treatment,the poorly crystallized oxides were transformed into crystalline anatase gradually and numerous nanoparticles formed on the oxide surface,leading to increased surface roughness at the nanoscale.The indentation deformation behaviors of oxide layer before and after water treatment were investigated and compared.Results show that under the indentation load,the untreated anodic TiO2 layer exhibited good adhesion to the substrate.In contrast,after water treatment,apparent oxides pile-up and spallation were observed around the indentation,indicating decreased adhesion strength.     

Improvement of erosion resistance of titanium with different surface treatments

To improve the erosion resistance of titanium, several surface treatment methods were applied: (1) duplex treatment with carbon nitride film deposited on a plasma-nitrided layer, (2) diamond coating, and (3) laser alloying. Duplex treatment could improve the erosion resistance of titanium under a low impact velocity of erosion particles. However, under a high velocity of erosion particles, because of the shallow depth of the plasma-nitrided layer and low load-bearing capacity of carbon nitride layer on the plasma-nitrided specimen, the improvement of erosion resistance was not significant. Diamond coatings with a thickness of 15 μm made no significant improvement on the erosion resistance of the titanium substrate. The large-area spallation of diamond coating during erosion was observed, probably due to the high residual stresses, poor load-bearing capacity, and brittle nature of diamond coatings. Compared with untreated Ti substrate, the erosion resistance of the laser-alloyed (nitrided) specimen was improved significantly. The erosion mechanisms for laser-nitrided titanium were characterized by chipping, brittle fracture, and formation of large flakes in the laser-nitrided layers.     

电解液成分对纯钛表面微弧氧化膜结构与生物活性的影响

采用微弧氧化处理技术,在纯钛TA2表面制备了含钙磷的多孔复合氧化膜,用SEM、XRD、EPMA等分析了电解液成分对氧化膜形貌、成分、相构成及生物活性的影响。结果表明:纯钛表面微弧氧化后原位生成的含钙磷多孔性复合氧化膜由锐钛矿相TiO2,金红石相TiO2和基体Ti组成;随电解液中钙磷摩尔比(Ca/P)值的增大,表面孔洞数量增多、直径变小,膜中Ca/P值增大,锐钛矿相TiO2减少、金红石相TiO2增多;当电解液中Ca/P=5时得到的氧化膜的Ca/P值为1.528,将该样品经碱液处理后再在快速钙化溶液(FCS)中浸泡2 d后即有羟基磷灰石HA形成,表明其具有良好的生物活性。     

TC4合金双辉等离子渗Cr高温氧化行为

研究了双层辉光等离子渗Cr对TC4合金650、750、850℃恒温氧化性能的影响。结果表明：渗Cr后,表面梯度合金层显著提高了TC4合金的高温氧化性能,Ti-Cr互扩散层可有效阻止氧向基体扩散。氧化过程中,Ti、Cr向外扩散形成TiO2/Cr2O3氧化膜,其形态与氧化温度有关。850℃氧化100 h后,渗Cr试样表面形成致密Cr2O3膜,恒温氧化性能优于NiCrAlY热障涂层。     

纯钛表面TiO2多孔膜的制备及其晶型研究

以硫酸为电解液,纯钛(TA1)为阳极,铜片为阴极,以恒压和恒流阳极氧化方式在钛表面直接获得锐钛型和金红石型TiO2多孔膜.采用X射线衍射仪对覆在钛基体上的阳极氧化膜进行了结构分析,研究了电压、硫酸浓度、阳极氧化时间和电流密度对TiO2多孔膜晶型的影响,并讨论了其形成机理.结果表明:在0.5 mol/L硫酸溶液中,恒压(≥80 V)或恒流(≥0.6 A)时出现锐钛相TiO2;恒压(≥100 V)1 min时即可出现锐钛相TiO2;恒压(≥150 V)或恒流(≥0.8 A)时出现金红石相TiO2.     

脉冲电子束抛光改性处理对TC21钛合金表面形貌的影响

采用脉冲电子束对TC21钛合金表面进行照射处理,利用光学显微镜、原子力显微镜分析了表面形貌,在轮廓仪上测定了脉冲电子束处理前后试样的表面粗糙度Ra和Ry,利用扫描电镜对脉冲电子束改性处理与未处理试样的横截面进行观察和分析,研究脉冲电子束改性机理.试验结果表明,脉冲电子束可以显著改善TC21钛合金的表面粗糙度,其抛光改性的机理是厚约10 μm表层在脉冲电子束的照射下发生高温瞬时熔凝,使表面变得平整和光滑.     

退火温度及TiO_2结构对羟基磷灰石的沉积诱导作用

采用阳极氧化法在钛金属表面制备TiO2薄膜,将表面改性的钛金属在过饱和钙化溶液中浸泡,在其表面沉积羟基磷灰石,研究了退火处理温度对TiO2薄膜晶型转变的影响以及TiO2的晶型结构对羟基磷灰石的诱导沉积作用。研究表明,300℃退火处理,TiO2薄膜为板钛矿相,500℃退火处理转变为锐钛矿相,高于500℃退火处理,锐钛矿相开始向金红石相转变。其中锐钛矿相的TiO2对羟基磷灰石的沉积具有最好诱导作用,沉积物分布均匀,板钛矿相对羟基磷灰石的诱导作用最差,所形成的沉积层是由片状的羟基磷灰石围成的多孔结构。     

钛及钛合金高温氧化行为研究

对工业纯钛TA2、TC4及Ti60合金分别在600、700、800℃进行氧化,得到氧化增重曲线.利用SEM、XRD等手段对氧化表面形貌、氧化产物构成及分布进行研究并分析了3种钛材在不同温度下的氧化机制.结果 表明:随着温度升高,TA2、TC4以及Ti60三种钛材的抗氧化能力均有所下降,且抗氧化能力由强到弱依次为Ti60...     

Ti-6Al-4V合金表面的热氧化/真空扩散处理

利用热氧化后真空扩散处理工艺在Ti-6Al-4V合金表面制备了与基体结合良好的硬化层，并在空气和真空条件下分别进行了摩擦磨损试验。结果表明，硬化层由表面氧化物薄层和氧扩散区组成，硬化深度可达60μm。经840℃真空扩散后，在表面硬化层中发现有Ti3A1相形成，使沿层深方向的硬度下降趋势变缓。热氧化／真空扩散处理可有效地降低在空气和真空中的Ti-6Ai-4V合金与GCrl5钢的干摩擦因数，提高Ti—6A1—4V合金在空气和真空中的的磨损抗力。