钛表面不同厚度氧化钛纳米管层的摩擦磨损行为*

为了改善钛的摩擦学性能,采用阳极氧化法在钛表面制备了纳米管径约100nm,厚度分别为500nm、1 000nm和1 500nm的TiO2纳米管层,并在450℃保温3h进行热处理。对试样的表面形貌、显微硬度和粗糙度进行测试。利用摩擦磨损试验考察了热处理前后不同试样在大气环境下的摩擦磨损行为。结果表明:干摩擦下,纳米管层的存在降低了钛与GCr15轴承钢球之间的摩擦系数;随TiO2纳米管层厚度的增加,试样的摩擦因数逐渐降低,磨损逐渐下降;热处理使纳米管由无定型氧化钛转变为锐钛矿晶型,进一步降低了摩擦因数,增加了钛的耐磨性能;纳米管层的磨损机制为磨粒磨损,接触疲劳磨损和粘着磨损。     

Al／Pb-Ag阳极在锌电积过程中的阳极行为和微观结构

采用循环伏安曲线（CV）和电化学交流阻抗谱（EIS）研究Pb-0.8%Ag 和Al/Pb-0.8%Ag阳极在最初24 h锌电积过程中的阳极行为和析氧动力学。结果表明：2种阳极材料在阳极极化过程中的阳极行为和动力学的多种变化表明阳极表面膜的形成和稳定。与传统的Pb-0.8%Ag阳极相比,Al/Pb-0.8%Ag阳极具有较长的极化时间。在最初的电积过程中,阳极表面中间产物的转变使2种阳极都表现出较高的析氧电位。随着析氧电位降低,析氧反应速率可以由阳极表面最初的生成物和中间产物S-OHads推断。随着电积的持续进行,Al/Pb-0.8%Ag阳极的析氧电位逐渐降低,Al/Pb-0.8%Ag阳极比Pb-0.8%Ag 阳极先达到稳定状态。电积24 h后,阳极电位由阳极表面的生成物和中间产物控制。采用扫描电子显微镜观察Al/Pb-0.8%Ag 和Pb-0.8%Ag阳极锌电积24 h后的微观形貌。     

Al/Pb-Ag阳极在锌电积过程中的阳极行为和微观结构（英文）

采用循环伏安曲线(CV)和电化学交流阻抗谱(EIS)研究Pb-0.8%Ag和Al/Pb-0.8%Ag阳极在最初24 h锌电积过程中的阳极行为和析氧动力学。结果表明:2种阳极材料在阳极极化过程中的阳极行为和动力学的多种变化表明阳极表面膜的形成和稳定。与传统的Pb-0.8%Ag阳极相比,Al/Pb-0.8%Ag阳极具有较长的极化时间。在最初的电积过程中,阳极表面中间产物的转变使2种阳极都表现出较高的析氧电位。随着析氧电位降低,析氧反应速率可以由阳极表面最初的生成物和中间产物S-OHads推断。随着电积的持续进行,Al/Pb-0.8%Ag阳极的析氧电位逐渐降低,Al/Pb-0.8%Ag阳极比Pb-0.8%Ag阳极先达到稳定状态。电积24 h后,阳极电位由阳极表面的生成物和中间产物控制。采用扫描电子显微镜观察Al/Pb-0.8%Ag和Pb-0.8%Ag阳极锌电积24 h后的微观形貌。     

氧化钛纳米管阵列的表面聚集控制及光电化学特性

采用阳极氧化法在有机介质中制备垂直排列的厚度达百微米的TiO2纳米管阵列,重点考察TiO2纳米管表面形貌特性的控制,以期从微观修饰角度来提高TiO2纳米管阵列膜的光电化学性能;在此基础上,考察不同处理条件下的TiO2纳米管阵列膜的光电化学特性。实验结果表明:采用无水乙醇作为超声液并结合二次蒸馏水进行漂洗能彻底清除纳米管表面聚集堵塞部分,得到清洁、规整有序的纳米管阵列表面,且不破坏纳米管阵列膜的最佳超声振动时间为20～30s。在对纳米管阵列的表面形貌特性进行控制后,采用一步阳极氧化法+无水乙醇超声制备的样品经500℃退火在全谱段的光转换效率达到1.48%,证实对纳米管阵列的表面形貌特性实施控制能有效提高其光电化学性能。     

电化学刻蚀对钛基IrO2-Ta2O5电极性能的影响

采用电化学刻蚀处理钛基材,再通过涂覆、烧结的方法制备出钛基IrO2-Ta2O5电极。与喷砂处理相比,经电化学刻蚀处理后,钛基材表面的凹坑分布更均匀,涂覆涂层后的钛基IrO2-Ta2O5电极的表面凹坑深浅均匀,呈规则分布。强化寿命测试结果表明,经电化学刻蚀处理后制备的钛电极强化寿命平均值达到20d,比喷砂处理后制备的电极寿命（16d）显著提高20％;电化学刻蚀处理后制成的钛电极析氧电位为1．62—1．73V,明显低于喷砂后制备的钛电极（1．92V）,电解时可降低电耗。     

钛基DSA阳极在电镀铬工艺中的应用研究

通过Hull槽电解、电化学特性和长期稳定性测试的方法研究了DSA (IrO₂,Ta₂O₅),DSA (IrO₂,Pt) 阳极和PbSn合金阳极在电镀铬溶液中的性能,并进行对比分析。结果表明,钛基DSA阳极真实活性比表面远远大于其几何表面;在镀铬溶液中表现出较低的析氧电位和较好的电催化活性,尤其是DSA (IrO₂,Pt) 阳极在高电流密度下表现出更好的电催化活性;但是由于溶液中的F^-添加剂侵蚀Ti基体使得钛基涂层阳极在镀铬溶液中的稳定性和寿命均比PbSn合金阳极短。     

硝酸铀酰溶液中不锈钢电极表面沉积氧化膜的行为研究

用动电位极化法研究了不锈钢(1Crl7)电极在NaCl-UO2(NO3)2溶液中的电化学行为．在阴极反应区。由于氢的不断释放，导致铀酰离子在不锈钢电极上析出．随着极化电位向阳极区移动，不锈钢电极发生阳极氧化。形成了氧化铀沉积膜．SEM对析出物和沉积膜的形貌进行了分析．AES深度剖析沉积膜的厚度约为40nm．XPS分析证实不锈钢腐蚀电极表面沉积膜中铀为U(Ⅵ)．     

钛基RuOx-PdO电极电催化氧化降解苯胺研究

电化学氧化法是难降解有机物降解处理的1种有效方法,高效电极材料是该技术得以实现的关键,近年来,金属氧化物电极的研究倍受重视.作者制备了钛基RuOx-PdO电极,并以其为阳极进行了苯胺的电催化氧化降解研究.发现该电极对苯胺有较好的电催化氧化性能在以NaCl(1g/L)为支持电解质、初始pH=5.0、电流密度=20mA?cm-2的条件下,对浓度为640mg/L的苯胺溶液电催化氧化降解1h,苯胺去除率可达99.4%,溶液COD(化学需氧量)去除率达84.0%,电极具有较长使用寿命.苯胺的去除主要是活性氯的间接氧化作用实现的,苯胺降解中间产物的去除则是活性氯间接氧化和电极直接氧化协同作用的结果.用GC-MS检测到苯胺电催化氧化过程中有对氯苯胺、2,4-二氯苯胺、2,4,5-三氯苯胺和苯醌等中间产物生成,据此探讨了苯胺的降解途径.     

钛基PbO2电极上苯酚的电化学氧化

以Ti为基体，通过热分解Pb（NO3）2水溶液制备了Ti／PbO2电极以及含有SnO2＋Sb2O3中间层的Ti／SnO2＋Sb2O3／PbO2电极，并将所制备的电极应用于模拟苯酚废水的电化学氧化降解。结果表明：含有SnO2＋Sb2O3中间层的Ti／SnO2＋Sb2O3／PbO2电极在相同的操作电流密度下，槽电压低于未加中间层的Ti／PbO2电极。以聚合前驱体制得的Ti／SnO2＋Sb2O3／PbO2电极为阳极时，在25℃，电流密度15mA／cm^2下，恒电流电解浓度为2．13×10^-3mol／L的模拟苯酚废水，电解3．0h后，苯酚浓度降为1．67×10^-5mol／L，苯酚去除率达99．2％；电解6．5h后，COD下降率为84.3％。阳极寿命快速检测实验结果表明，添加锡锑中间层后的Ti／SnO2＋Sb2O3／PbO2电极，其寿命显著提高。     

钛基IrSiCe复合电极的制备及在电沉积钴中的应用

采用热分解法制备Ti/IrO2-SiO2及Ti/IrO2-SiO2-CeO2复合氧化物阳极。采用SEM分析对比掺入CeO2前后电极表面形貌的变化,采用循环伏安曲线及析氧极化曲线将自制Ir-Si-Ce电极与自制Ir-Si电极及商品电极（Ir-Ta-Sn、Ir-Ru、Ir-Ta、Ir-Sn）进行分析对比。采用双膜三室电沉积法从氯化钴溶液中回收钴,探讨自制电极与商品电极槽电压、能耗及抑氯性能优劣。结果表明：掺杂稀土Ce有利于提高电极表面粗糙度、增大其活性表面积、提高其电催化活性;相比于Ir-Si、Ir-Ru、Ir-Sn、Ir-Ta、Ir-Ta-Sn电极,Ir-Si-Ce电极析氧电位最低、电催化活性最高;电沉积回收钴实验中,相比于其它电极,Ir-Si-Ce电极槽电压及能耗最低、抑氯性能最好,氯气削减率高达97.5%。     

Improved oxidation resistance of Ti with a thermal sprayed Ti3Al(O)–Al2O3 composite coating

A Ti₃Al(O)–Al₂O₃ in situ composite was explored as a coating system for Ti using thermal spray. Oxidation tests at 700–800 °C showed that this coating remarkably decreased the oxidation rate and increased the scale spallation resistance compared with Ti. The mechanisms for these improvements were then briefly discussed.     

La掺杂对Ti/Sb-SnO2电极改性机制的研究：电化学分析

为研究稀土掺杂对Ti/Sb-SnO_2催化电极的改性机理,采用溶胶凝胶法制备了La掺杂Ti/Sb-SnO_2电极,以苯酚为目标有机物,考察了电极的电化学性能。极化曲线和Mott-Schottky分析表明:La改性Ti/Sb-SnO_2电极的析氧电位先增大后减小,且在2.0 V电位下Sn:Sb:La(摩尔比)为100:10:1.5时电极交换电流密度值最大;改性后电极的平带电势负移,Mott-Schottky拟合直线斜率从2.96降为1.66,活性表面积增大,载流子浓度提升。循环伏安和交流阻抗分析表明:掺杂后电极电化学反应电阻减小,活性电荷由14.1μF提升至322μF;苯酚直接氧化峰电流增大,峰电位减小。以上结果解释了电极电催化活性提升的内在原因。     

Synthesis and electrochemical properties of Li4Ti5O12

The spinel compound Li₄Ti₅O₁₂ was synthesized by a solid state method. In this synthesizing process, anatase TiO₂ and Li₂CO₃ were used as reactants. The influences of reaction temperature and calcination time on the properties of products were studied. When calcination temperature was 750 °C and calcination temperature was 24 h, the products exhibited good electrochemical properties. Its discharge capacity reached 160 mAh g⁻¹ and its capacity retention was 97% at the 50th cycle when the current rate was 1 C. When current rate increased to 10 C, its first discharge capacity could reach 136 mAh g⁻¹, and its capacity retention was 85% at the 50th cycle.     

Effect of La2O3 on corrosion resistance of laser clad ferrite-based alloy coatings

The ferrite-based alloy powders with different contents of La₂O₃ were laser clad on a steel substrate. The microstructural features and phase structure of these coatings were studied by scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The results showed that the microstructure of the coatings with La₂O₃ was refined and purified. The main phase of the coatings was γ (Fe, Ni). Moreover, the electrochemical properties of the coatings were investigated by anodic polarization curves and electrochemical impedance spectroscopy (EIS). Anodic polarization results indicated that both polarizing voltage and polarization current density were reduced with the addition of La₂O₃. EIS results showed that, with the increment of La₂O₃, the inductive arcs shrunk and capacitive arcs expanded. The inductive arc at low frequency was disappeared and changed to capacitive arc thoroughly when the content of La₂O₃ reached 1.2 wt.%. The corrosion weight loss experiment results showed that the corrosion rate was lower and the corrosion attack was lighter in the coatings with La₂O₃ than that without La₂O₃, resulting in a substantial improvement of the corrosion resistance.     

Synthesis of Er2Ti2O7 nanocrystals and its electrochemical hydrogen storage behavior

Ultrafine Er₂Ti₂O₇ was synthesized at 700 °C within 2 h by a soft-chemistry route named citric acid sol–gel method (CAM). The obtained Er₂Ti₂O₇ with high dispersibility was square-like and the average size was about 70 nm. The prepared Er₂Ti₂O₇ nanocrystals in 6 M KOH aqueous solutions were investigated as a hydrogen storage material. It was found that the Er₂Ti₂O₇ powders would function as electrochemical hydrogen storage, showed fair electrochemical reversibility, and considerably high charge–discharge capacity. The reversible discharge capacity of the Er₂Ti₂O₇ electrode was found to exceed 320 mAh/g and adsorption capability of hydrogen is up to 1.27% at a current rate of 100 mA/g. In addition, the cycling ability and high rate capability of the Er₂Ti₂O₇ electrode are fairly good with only 4% capacity decay after 25 cycles. Cyclic voltammograms (CVs) were carried out to further examine the electrochemical hydrogen storage mechanism of Er₂Ti₂O₇.     

Oxidation and interfacial fracture behaviour of NiCrAlY/Al2O3 coatings on an orthorhombic-Ti2AlNb alloy

Al₂O₃ diffusion barriers of various thicknesses have been fabricated by filtered arc ion plating between the NiCrAlY coating and the O-Ti₂AlNb alloy. Isothermal oxidation tests and three-point bend tests have been conducted to investigate the influence of the Al₂O₃ diffusion barriers on the oxidation and interfacial fracture behaviour of the coatings. The results indicate that the Al₂O₃ diffusion barrier defers interdiffusion and gives oxidation resistance of the NiCrAlY coatings. The thickness of the Al₂O₃ interlayer not only influences the oxidation behaviour but also affects the interfacial fracture properties. Additionally, thermal exposure affects the critical load in three-point bend tests.     

Spectrophotometric study of the anodic corrosion of Ti/RuO2 electrode in acid sulfate solution

Electrochemical properties of RuO₂-based electrode, particularly the oxygen evolution and anodic dissolution of RuO₂ have been investigated in 0.5 mol dm⁻³ H₂SO₄ solution by means of polarization measurements and product analysis. It has been demonstrated that it is possible to determine very low concentration of dissolved ruthenium species (8 × 10⁻¹⁰ mol dm⁻³ Ru) by a sensitive spectrophotometric method based on the ruthenium-catalyzed ceric-arsenite reaction.Finally, the probable mechanism of anodic dissolution of RuO₂-based electrode, has been proposed.     

Ion-plated Al-Al2O3 films as diffusion barriers between NiCrAlY coating and orthorhombic-Ti2AlNb alloy

Ion-plated Al-Al₂O₃ cermet films were fabricated as diffusion barriers between NiCrAlY coating and orthhombic-Ti₂AlNb alloy. The oxidation and interdiffusion behaviour of coatings with and without diffusion barrier were investigated in isothermal and cyclic oxidation tests at 800 °C. The results indicated that substantial interdiffusion and rapid oxidation degradation occurred in the coated specimens without diffusion barrier. With Al-Al₂O₃ diffusion barriers, deferred interdiffusion and improved oxidation resistance was observed. Among them, duplex coating containing 1Al-Al₂O₃ interlayer exhibited the best performance. Coefficient of diffusion hindering and factor of reaction hindering were proposed to compare and quantify the efficiency of the diffusion barriers.     

Oxygen release behaviour of Ce(1−x)ZrxO2 powders and appearance of Ce(8−4y)Zr4yO(14−δ) solid solution in the ZrO2–CeO2–CeO1.5 system

To clarify the existence of metastable phases in the ZrO₂–CeO₂–CeO_1.5 system, evolved-oxygen gas analyses, (EGA), by heating a single phase of t′ and t″ (Ce_(1−x)Zr_xO₂) with various compositions, x, in a reducing gas and successive oxidation were carried out repeatedly. The oxygen release behaviour of the t′ and t″ phases was very complicated. The single κ phases, (Ce_(1−x)Zr_xO₂) with the composition, x=0.5 and 0.6, which were obtained by oxidizing the resulting pyrochlore as a precursor in O₂ gas at 873 K, exhibited a sharp oxygen release at the lowest temperature; the composition range of κ phase may be x=0.450.65. A new tetragonal phase t*, (Ce_(1−x)Zr_xO₂), which was attained by cyclic redox process together with annealing in O₂ gas at 1323 or 1423 K, exhibited a sharp oxygen release at the highest temperature; the composition range of t* phase may be as wide as x=0.200.65. A metastable solid solution expressed by a chemical formula of Ce_(8−4y)Zr_4yO_(14−δ) (y=01) possessing a CaF₂-related structure appeared on deoxidation of the t* phase. A ternary phase diagram containing the t* and Ce_(8−4y)Zr_4yO_(14−δ) solid solution was proposed.     

Porous TiO2 film prepared by micro-arc oxidation and its electrochemical behaviors in Hank's solution

Porous titanium oxide film was prepared by micro-arc oxidation (MAO) method on the surface of titanium alloy in electrolyte containing Ca and P. Surface characterizations of the film were carried out using X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) before and after immersion in Hank's solution. Electrochemical behaviors and corrosion resistance were studied by electrochemical techniques. The film was mainly composed of titania, α-tricalcium phosphate (α-TCP) and amorphous Ca-P compounds. α-TCP and amorphous compounds could transformed into hydroxyapatite (HA) when immersed in Hank's solution. MAO film showed higher corrosion potential and lower corrosion current than the titanium alloy and its chemical stability was slightly changed after formation of HA. Fitted electrochemical impedance spectroscopy (EIS) data indicated that after immersion for 2 weeks the MAO film kept good corrosion resistance. Porous TiO₂ film on titanium alloy by MAO method showed good chemical stability in Hank's solution and the transformation of Ca-P compounds into HA indicated that MAO was an effective method for preparing titanium alloys as bioactive artificial bone substitute even when Ca and P in the tissue environment were not abundant.