微弧氧化钛合金的电化学腐蚀行为

采用微弧氧化技术在TC4钛合金表面制备了多孔陶瓷层,研究了其在Hank′s模拟体液中的电化学腐蚀行为,利用SEM和XRD分析了其表面形貌和物相组成。结果表明,微弧氧化合金的自腐蚀电位升高约0.3V,提高了TC4钛合金在生物体液环境下的化学稳定性。在钛合金植入体电位范围内,微弧氧化处理可明显提高极化电阻,减少腐蚀电流1~2个数量级。随腐蚀时间的延长,TC4钛合金表面钝化膜逐渐发生腐蚀,而微弧氧化膜浸泡初期HA的形核及生长是电极反应中最活跃部分,2周后表面形成均匀的HA薄膜,表现出良好的抗电化学腐蚀性能。     

钛合金表面微弧氧化／水热处理复合陶瓷层的性能研究

对微弧氧化后的Ti6Al4V合金表面进行了水热处理,对处理后涂层的成分、形貌及其在Hank's模拟体液中的腐蚀性能进行了研究.试验结果表明:水热处理后,微弧氧化层中以无定形态钙磷酸盐存在的Ca、P元素转化为针状羟基磷灰石,厚度约为5μm,并在微弧氧化膜微孔边缘和底部优先生长.与微弧氧化层相比,水热处理后涂层的粗糙度明显下降,同时显微硬度下降约1/3.电化学腐蚀试验表明:微弧氧化显著改善了钛合金在模拟体液中的耐腐蚀性能;水热处理钛合金自腐蚀电位低于纯钛合金,但当处于人体电位0.4～0.6V(vs.SCE)范围时,微弧氧化/水热处理钛合金的腐蚀电流比纯钛合金低1个数量级.     

水热反应液浓度对TC4钛合金微弧氧化涂层硬度和摩擦性能的影响

针对TC4钛合金耐腐蚀性偏低的问题,本文利用微弧氧化技术在TC4钛合金表面制备陶瓷涂层,探究电解液中水热合成液浓度对TC4钛合金微弧氧化(MAO)涂层硬度和摩擦行为的影响。利用XRD、SEM、摩擦试验机等设备对水热处理的TC4钛合金微弧氧化进行表征。研究结果表明:随着水热反应液浓度增加,TC4钛合金微弧氧化涂层中金红石相Ti O2衍射峰逐渐加强,锐钛矿相Ti O2减弱。在水热处理24 h后,在水热反应试验条件下能实现羟基磷灰石颗粒的合成,并且反应液浓度越高,获得的羟基磷灰石越多。水热合成浓度增加,有助于TC4钛合金涂层表面平整度增加。水热处理后的TC4钛合金MAO涂层的显微硬度呈现出先增加后降低的趋势。水热处理TC4钛合金MAO涂层的摩擦因数在0. 95～1. 1之间,水热合成液的浓度对摩擦因数影响不明显。     

纯Ti表面微弧氧化-碱热处理仿生陶瓷膜的制备及耐蚀性

采用微弧氧化-碱热处理在纯Ti表面制备了含有羟基磷灰石(HA)的仿生陶瓷膜。利用SEM,XRD和电化学工作站等手段研究了膜层的形貌、物相及其耐蚀性。结果表明:在乙酸钙-磷酸二氢钙电解液体系中微弧氧化(MAO),纯Ti表面形成一层含Ca和P的TiO2多孔陶瓷膜。经水热处理后,膜层表面的孔洞变小、致密性增加,膜层中还出现了鳞状、层片状以及针棒状的HA。在Hank's模拟体液中,MAO膜和微弧氧化-碱热处理(MAOAH)膜均表现出较好的耐蚀性。MAO膜经模拟体液腐蚀后,形成了缺钙型HA(Ca8.86(PO4)6(H2O2)2)和CaTiO3;而模拟体液中的阴离子与MAOAH膜层的氧化物作用使膜层孔洞直径和深度增加。     

溶液钙浓度和水热合成条件对微弧氧化TiO2／羟基磷灰石复合膜层形貌和组成的影响

钛在含钙磷的溶液中微弧氧化，表面形成含有钙磷元素的，均匀多孔的氧化膜层，水热合成后转化为含羟基磷灰石晶体的复合氧化膜。研究表明：钙离子浓度未使膜层的形貌和相组成发生明显变化；仅在较低的浓度下增加溶液Ca^2 的浓度，膜层中Ca，P元素的相对含量和Ca／P比都会增加；在不同的水热温度和溶液钙浓度下，得到的羟基磷灰石具有不同的晶体形貌，相对含量和Ca／P比；缩短恒温时间可以使HA晶粒细化。这为优化生物医用钛表面TiO2／羟基磷灰石复合膜层的成分和形貌提供了依据。     

氧化时间对钛表面微弧氧化膜层的影响

采用恒电流微弧氧化技术,在钛表面制得含HA的TiO2陶瓷膜,考察了氧化时间对氧化膜微观形貌、膜厚、相结构及耐体液腐蚀性能的影响。结果表明,随氧化时间增长,膜层表面多孔形貌变化明显,膜层厚度呈先增后降的趋势。氧化时间延长,膜层相组成由金红石、锐钛矿为主变为以羟基磷灰石为主。模拟体液极化曲线分析表明,微弧氧化膜的钝化行为随氧化时间延长而优异,但氧化时间超过20 min后,增大氧化时间对钝化效果的影响不再明显。     

水热处理后TC4钛合金微弧氧化涂层的润湿性和电化学性能分析

针对TC4钛合金耐腐蚀性偏低、生物相容性差等问题,本试验利用微弧氧化(MAO)技术在TC4钛合金表面制备陶瓷涂层,结合水热合成技术在TC4钛合金涂层中引入具有生物活性的羟基磷灰石层,探究水热合成液浓度变化对TC4钛合金涂层的润湿性能和电化学行为的影响。利用XRD、SEM、润湿角测量仪、激光共聚焦显微镜以及电化学工作站等对TC4钛合金MAO涂层的相组成、表面形貌、润湿角、表面粗糙度、电化学性能等进行表征。研究结果表明:随着水热合成液浓度增加,TC4钛合金MAO涂层中金红石相TiO_2含量有所提高,羟基磷灰石(HA)相含量逐渐增加。水热合成液浓度的变化对TC4钛合金MAO涂层表面粗糙度的影响不大,粗糙度在1～2μm范围内。在水热合成处理后,TC4钛合金涂层的极化曲线会向正电位方向移动,腐蚀电位增加,腐蚀电流密度降低,降低幅度约为一个数量级。     

水热处理参数对Ti6Al4V合金微弧氧化膜HA生成的影响

采用微弧氧化的方法在Ti6Al4V合金表面生成一层富含Ca和P元素的氧化膜,对其进行水热处理,并生成具有生物活性的羟基磷灰石(HA)涂层.研究了处理介质为氨水(pH=10)时,水热处理温度、水热处理时间、冷却条件及填充度对水热处理后钛合金微弧氧化膜表面生成羟基磷灰石的影响.结果表明:随着处理温度和保温时间的延长,HA数量增多,颗粒增大;随釜冷却处理比空冷处理得到的HA更加粗大,并且分布更加均匀致密;填充度增加,HA分布趋于均匀但是形状趋向不规则.     

表面微弧氧化处理对球拍钛合金摩擦磨损性能的影响

在TA1、TC10和TC4钛合金基材表面制备了微弧氧化膜层,研究了三种不同微弧氧化膜层的显微组织、表面粗糙度、硬度、磨损失重和摩擦磨损形貌。结果表明:在相同微弧氧化工艺下,TA1、TC10和TC4钛合金表面形成了形貌不同的微弧氧化膜层;经过微弧氧化处理后,TA1和TC10表面膜层的磨损失重都要小于基材,而TC4合金表面膜层的磨损失重要略高于基材;TC10合金表面膜层的磨损失重最小,具有最佳的抵抗摩擦磨损的特性;钛合金基材的磨损机制主要为粘着磨损和局部剥落;而三种微弧氧化膜层的磨损机制为粘着磨损,摩擦磨损形貌的观察结果与磨损失重测试结果较为吻合。     

固溶处理对β钛合金微弧氧化膜生长过程的影响

目的 在不同固溶热处理工艺的β钛合金上制备微弧氧化膜,研究其在微弧氧化初期的生长特性。方法 对比铸态、750 ℃固溶、850 ℃固溶β钛合金表面微弧氧化初期（0~120 s）氧化膜的厚度、表面形貌、相组成及电化学腐蚀性能变化,研究热处理与膜层特性之间的关系,并分析热处理对氧化膜表面裂纹的产生及膜层生长的影响规律。结果 固溶处理改变了基体合金的相组成,元素分布随之改变,热处理后试样表面更容易起弧。较未热处理试样,氧化时间为120 s时,固溶处理后所获膜层的厚度更薄且致密。微弧氧化膜微观形貌显示,经750 ℃固溶热处理后的试样,在微弧氧化后,其膜层表面裂纹最少。极化曲线显示,750 ℃热处理试样氧化膜的耐蚀性优于850 ℃热处理试样。结论 经过750 ℃固溶处理后的合金试样,由于其元素分布均匀,使得微弧氧化初期放电均匀,更易获得致密的微弧氧化膜,膜层的综合性能较好。     

医用镁合金丝材的微弧氧化表面改性(英文)

在硅酸盐-磷酸盐复合电解质中添加羟基磷灰石纳米粉体和氢氧化钠进行改性处理,然后采用该电解质对医用镁合金丝材进行微弧氧化处理。研究电解质中氢氧化钠含量对镁合金丝材表面陶瓷涂层微观组织结构和性能的影响。结果表明:对电解质改性后,镁合金丝材的微弧氧化起弧电压大降低且氧化速度更快。镁合金丝材在添加2 g/L氢氧化钠的电解质中进行微弧氧化处理后的耐腐蚀性能改善幅度显著。在模拟体液的早期浸泡过程中,微弧氧化处理过的镁合金丝材表现为缓慢且稳定的腐蚀降解。在浸泡28 d后,镁合金丝材表面的保护性陶瓷涂层尚未破坏,但浸泡60 d后,镁合金丝材出现了显著的腐蚀降解。     

钛合金表面GO/HA/MAO复合膜层的制备及其性能

为了改善钛合金种植体在体液中的腐蚀及摩擦腐蚀行为,延长其在人体环境中的服役时间,在微弧氧化 (MAO)膜层上采用溶胶凝胶(Sol-gel)法于羟基磷灰石(HA)和氧化石墨烯(GO)的混合溶胶中浸渍提拉成膜,从而在 Ti6Al4V 合金表面成功地制备了 GO/ HA/ MAO 复合膜层。 结果表明,MAO 膜层表面的微孔及微球被 GO/ HA 薄膜有效的覆盖且较为致密;膜层的物相组成主要为金红石相及锐钛矿相的 TiO₂、HA、SiO₂ 和GO;根据电化学腐蚀和摩擦腐蚀结果分析知,GO/ HA/ MAO 复合膜层在模拟体液(SBF)中的耐蚀性及耐摩擦腐蚀性相比于 MAO 膜层和 Ti6Al4V 基体均得到了显著提高。     

Structure of calcium titanate/titania bioceramic composite coatings on titanium alloy and apatite deposition on their surfaces in a simulated body fluid

In this study, TiO₂-based coatings containing Ca and P ions were prepared on titanium alloy surfaces by microarc oxidation (MAO). After soaking in aqueous NaOH solution and subsequent heat treatment at 700 and 800 °C, calcium titanate/titania bioceramic composite (CTBC) coatings were obtained. The results show that the outer layers (0–1.5 μm) of the CTBC coatings are mainly composed of Ca, Ti, O and Na constituents with a uniform distributions with increasing the depth near the surfaces. The surface phase compositions of the CTBC coating formed at 700 °C are anatase, rutile and CaTi₂₁O₃₈ phases, as well as a few CaTiO₃, while those of the CTBC coating formed at 800 °C are anatase, rutile and CaTiO₃. When incubated in a simulated body fluid (SBF), apatite was deposited on the CTBC coatings probably via formation of hydroxyl functionalized surface complexes on the CTBC coating surfaces by ionic exchanges between (Ca²⁺, Na⁺) ions of the CTBC coatings and H₃O⁺ ions in the SBF. The CTBC coating formed at 800 °C seems to facilitate the deposition of Ca and P probably due to the good crystallographic match between perovskite CaTiO₃ and HA on specific crystal planes.     

Microstructure and in vitro bioactivity of laser-cladded bioceramic coating on titanium alloy in a simulated body fluid

In order to obtain bioactivity on the surface of titanium alloy, the bioceramic coating on Ti–6Al–4V was designed and fabricated by laser cladding. The microstructure and bioactivity of laser-cladded bioceramic coating were investigated in vitro via soaking in a simulated body fluid (SBF). The results indicated that the laser-cladded bioceramic coating was metallurgically bonded to the substrate and contained such bioactive phases as hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP). A bone-like apatite layer was spontaneously formed on the surface of laser-cladded coating merely soaked in SBF for 7 days. And the appearance of flake-like and cotton-like morphology, which is the characteristic morphology of apatite, offered an advantageous condition for osseo-connection. The formation ability of apatite was remarkably accelerated on the surface of laser-cladded bioceramic coating compared with the untreated titanium alloy substrate.     

Mechanical properties of suspension plasma sprayed hydroxyapatite coatings submitted to simulated body fluid

Home synthesized (HA) powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto titanium substrate. The deposition process was optimized and the resulting coatings were soaked in simulated body fluid (SBF) for the periods of 3, 7, 14, 28, and 60 days at controlled temperature of 37 °C. The microstructural research enabled to find in the as-sprayed deposits two characteristic zones: (i) dense zone corresponding to the lamellas, observed usually in thermally sprayed coatings; (ii) sintered zone containing fine hydroxyapatite grains corresponding to the fine solids from initial suspension. The sintered zone disappears after soaking in SBF and the pores get filled by the reprecipitated calcium phosphates. The adhesion of the soaked coatings to the substrate was characterized by the critical load in the scratch test and was about 10 to 12 N. The Young modules of the coatings were determined with help of depth-sensing indentation test by the use of the technique developed by Oliver and Pharr. The modules were not depending on the time of soaking and their mean values were 15.6 and 28.4 GPa, depending on the coating operational parameters. The scratch test enables to determine the hardness of the coatings, which remained fairly constant during the time of soaking in the range of 3 to 5 GPa. This hardness was compared to that the Martens microhardness which doubled with time of soaking to reach up to 1 GPa.     

Preparation and structure of microarc oxidation ceramic coatings containing ZrO2 grown on LY12 Al alloy

Ceramic coatings containing ZrO2 were prepared in situ on LY12 aluminum alloy by microarc oxidation（MAO） in the mixed solution of zirconate and phosphate solution.The phase composition and morphology of the coatings were studied by XRD and SEM,respectively.The growing mechanism of ceramic coatings was discussed in a preliminary manner.The results show that with an increase in MAO time,the compactness of the coating improved and the thickness increased.From the inner layer to the coating surface,the content of Zr increased,while the content of Al decreased.In addition,the coating was composed of m-ZrO2,t-ZrO2,and a little amount of γ-Al2O3.With an increase in reaction time,the relative content of t-ZrO2 within the coating sharply decreased while the relative content of m-ZrO2 sharply increased,and then both generally kept at a constant level after 60 min.     

The effect of complexing agent on Ti alloy micro-arc oxidation(MAO) coatings in Ca-P electrolyte

Three new microarc (MAO) ceramic coatings were fabricated in the Ca-P electrolyte with three eco-friendly easily degradable complexing agent GA, TEA and EDTMPS and compared to that fabricated with the current common agent EDTA–2Na. A 3-Dimensional video microscope and scanning electro microscope were utilized to observe surface and cross-sectional morphology; the statistics of the coating surface were measured by the image software Image J × 2.0. Compositions of elements and phases were detected by the energy-dispersive X-ray spectroscopy and X-ray diffraction, respectively; X-ray photoelectron spectroscopy was further applied to provide more information about the components of the four complexing agents for MAO coatings surfaces. The surface morphologies show difference, which is a result of different quantity of melting metal during the treatment. The EDS results indicate that the elements compositions of the four MAO ceramic coatings are similar. The phases show little difference which is a result of the crystal transformation of TiO₂ in different physical characteristic electrolytes. The biocative tests of four complexing agent MAO coatings shows good bioactive performance. The surface morphology of MAO coatings could meet the demand of biological implanting. Corrosion resistance properties are improved effectively in simulated body fluid (SBF). The wetting angles are less than 90 degrees, which indicates better solid-liquid affinity. After 28 days of sedimentation experiments in SBF, the white substance-carboxyl apatite (HA) generate on the surface of the coatings. The biological activities of the four MAO coating samples are demonstrated.     

Influence of anions in phosphate and tetraborate electrolytes on growth kinetics of microarc oxidation coatings on Ti6Al4V alloy

The growth kinetics of microarc oxidation (MAO) coatings on Ti6Al4V alloy was studied by designing an electrolyte with low content and high content, using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and potentiodynamic polarization. The results showed that increased the spark intensity and dissolved most of the oxides at high temperatures. Then, a thicker barrier layer at the coating/substrate interface was produced, which increased the polarization resistance of the coating. at a low concentration also promoted the uniform growth of the MAO coating and the formation of hat-shaped holes in the outer deposition layer. The thickness of the MAO coatings obtained in Na₂B₄O₇ electrolytes exhibited an exponential increase with time at spark discharge stage, while that of the MAO coating obtained in phosphate–tetraborate electrolytes showed a linear trend as the content increased.     

SiC纳米颗粒对TA2微弧氧化涂层组织结构及耐蚀性能的影响机制

为提高钛及钛合金防腐蚀、耐磨损等关键服役性能,本研究在TA2钛合金表面制备微弧氧化陶瓷涂层,研究纳米SiC颗粒的添加对微弧氧化涂层组织结构及耐蚀性能的影响机制.结果表明,基础电解液中SiC的加入能够大幅度提高TA2微弧氧化涂层的厚度,且随着电压的升高,涂层的厚度和表面粗糙度也随之增大,涂层表面的微孔尺寸随着电压的升高而逐渐增大,SiC的加入能够有效地抑制微弧氧化涂层表面裂纹的产生;微弧氧化涂层的物相主要有高温稳定相金红石及锐钛矿,还含有少量的SiC及SiO2;微弧氧化涂层增加TA2的开路电位及自腐蚀电位,随着处理电压的增加开路电位随着升高;SiC的加入降低了涂层的阳极电流密度,显著提高了微弧氧化涂层得耐蚀性能。