有机介质中TiO2纳米管阵列的制备及生物活性研究

用含氟的有机溶剂二甲基亚砜(DMSO)作电解液,通过电化学阳极氧化法,在纯钛片表面制得长度达微米级TiO2纳米管阵列.研究了TiO2纳米管阵列形貌和晶相的转变,并通过模拟体液浸泡研究了其生物活性.采用扫描电镜(SEM) 、X射线衍射(XRD)、傅里叶红外(FT-IR)和透射电镜(TEM)分别对纳米管阵列的形貌和物相进行表征.结果表明:在40 V电压下,阳极氧化24 h,可以制得长12 μm,外径170 nm的无定形氧化钛纳米管阵列.300 ℃热处理后,TiO2纳米管表面开始收缩,由无定形向锐钛矿型转变, 温度升到600 ℃时,氧化钛纳米管表面形成较深的沟壑,锐钛矿型开始向金红石型转变,700 ℃热处理后,TiO2纳米管阵列被破坏.生物活性研究表明,具有TiO2纳米管阵列的钛片经热处理后具有良好的生物活性,能在模拟体液浸泡14 d诱导生成厚达13 μm的碳磷灰石层.     

二氧化钛纳米管阵列电极的光电化学性能研究

采用阳极氧化法在钛片上制备了垂直排列的TiO2纳米管阵列，利用SEMXRD对纳米管阵列的形貌和结构进行了表征，并通过电化学交流阻抗谱、光照开路电位谱和瞬态光电流谱技术对纳米管阵列电极的光电化学特性进行了研究。实验结果表明，TiO2纳米管的内径约为90nm，管壁约为10nm，纳米管阵列厚度约为500nm，经600℃退火处理后，转变为锐钛矿型与金红石型的混晶结构。光电测试结果表明，随着退火温度升高，TiO2纳米管阵列电极的界面电荷转移电阻减小，光电流逐渐增大，光照开路电压增大，至600℃达到最大，当退火温度继续升高，电极的光电性能急剧下降。与TiO2纳米多孔膜电极相比，光电性能显著提高，这主要归因于TiO2纳米管阵列更大的孔隙率和比表面积。     

离子浓度对TiO_2纳米管阵列的影响

采用阳极氧化法在纯钛片表面得到了一种规整有序的TiO2纳米管阵列.利用SEM观察纳米管阵列的形貌,用XRD分析其晶型.并考察了阳极氧化电压、F浓度和溶液的pH值对纳米管阵列形貌和长度的影响.以罗丹明B溶液为目标降解物研究了TiO2纳米管阵列的光催化活性.结果表明,F浓度不仅影响纳米管阵列的形成时间,而且对纳米管阵列的形貌和长度也有一定的影响;溶液的pH值不仅影响纳米管阵列的长度,在很大程度上也影响纳米管阵列的表面形貌.阳极氧化法制备的TiO2纳米管阵列为无定型,在450℃空气中焙烧2h晶相主要为锐钛矿型TiO2,表现出较好的光催化活性.     

TiO2纳米管阵列的制备、热处理及光催化性能

采用恒压直流阳极氧化法制备具有规则排列的TiO2纳米管阵列,并研究其在空气热处理过程中的晶型转变,同时用甲基橙的降解过程表征其光催化性能。结果表明：电解液采用0.5%（质量分数）HF水溶液时,电压在10～20V之间,时间5min以上才能形成TiO2纳米管阵列;随着氧化电压的提高,纳米管的平均管径和管长都增大;随着氧化时间的延长,纳米管管长明显增长,平均管径变化不大;纳米管阵列在空气中热处理时,280℃左右出现锐钛矿相,400℃左右出现金红石相,680℃左右锐钛矿相向金红石相的转变结束,600℃纳米管阵列结构仍然保持完整。光催化实验表明,在氧化电压为20V、氧化时间为20min时获得的纳米管阵列经过400℃热处理后,在40min的光照时对甲基橙的光催化降解率高达99.6%。     

用乳酸溶液为电解质制备TiO2纳米管阵列

为了开发自组织阳极氧化制备TiO2纳米管阵列的新体系,以乳酸／NH4F混合溶液为电解质,研究了阳极氧化制备TiO2纳米管阵列的影响因素及形成机理。采用X射线衍射（XRD）和扫描电子显微镜（SEM）对样品进行检测,并通过观察阳极氧化过程中的电流-时间变化曲线,探讨TiO2纳米管阵列的形成机理。结果表明：阳极氧化电压、时间及电解质溶液的黏度是影响TiO2纳米管阵列结构和形貌的主要因素,在40V阳极氧化电压下,制备出平均管径高达180nm的纳米管,所获得的TiO2纳米管阵列为无定型结构,300℃热处理以后转变为锐钛矿型TiO2。     

原位模板法在铝基底上制备TiO2纳米管阵列薄膜

采用液相沉积法，将铝基多孔阳极氧化铝（AAO）模板浸入到（NH4）2TiF6溶液中，制备出高度有序的TiO2纳米管阵列薄膜，并在不同的温度下进行了热处理。用场发射扫描电子显微镜、透射电子显微镜和X射线衍射仪等手段对试样的微观形貌、结构及物相进行了表征。结果表明，TiO2纳米管的形貌依赖于AAO的特征，薄膜是由外径大约200nm，壁厚约40nm的TiO2纳米管阵列组成，薄膜厚度约25μm。原位模板法制备的TiO2纳米管阵列薄膜为非晶态，在400℃空气中焙烧2h转变为锐钛矿相TiO2。经过650℃焙烧仍保持纳米管结构，表现出较好的热稳定性。     

多孔钛板表面TiO2纳米管阵列膜的制备及表征

利用四辊卧式粉末轧机制备多孔钛板,并通过阳极氧化工艺在轧制多孔钛板上制备TiO2纳米管阵列膜。采用扫描电子显微镜（SEM）和X射线衍射仪（XRD）分别对TiO2纳米管阵列膜的形貌和物相进行表征,并对TiO2纳米管阵列膜的热稳定性和生物相容性进行了研究。结果表明,多孔钛板上初步制备的TiO2纳米管阵列膜为无定形相结构,在不同温度下可转化为锐钛矿型、金红石型或锐钛矿与金红石型的混合物;细胞培养实验表明,经阳极氧化及450℃退火处理后,粉末轧制多孔钛板表面细胞的黏附量比未经处理的多,且细胞发育良好。     

纯钛表面二氧化钛纳米管阵列结构特征的研究

采用阳极氧化技术在纯Ti表面制备出有序的TiO2纳米管阵列,并通过SEM,XRD,XPS对TiO2纳米管阵列进行表征。结果表明,阳极氧化时间对纳米管的形成有较大的影响。在外加电压为20V,阳极氧化时间为20min时,可制备出长度约480nm、内径约89.90nm、壁厚约7.4nm的TiO2纳米管阵列。经450℃热处理后,可得到锐钛矿型的TiO2纳米管阵列,钛元素以Ti4+氧化态处于八面体的环境中,Ti2p3/2的结合能为459.3eV。     

水热温度对钛片表面制备TiO2纳米棒的影响

以NaOH为溶剂,利用水热法在医用钛表面制备了TiO2纳米棒,系统研究了水热温度对产物的影响以及TiO2纳米棒的生长机制。利用扫描电子显微镜（SEM）、X射线衍射仪（XRD）和接触角测定仪分析钛表面生成产物的形貌、物相组成和钛表面与水的接触角。结果表明,水热过程中,温度决定了产物的结构和形貌。当NaOH浓度为5 mol/L、热处理温度为450℃、水热温度为130℃时,钛表面可以生成分布及尺寸均匀、长度基本一致的TiO2纳米棒,其长度约为200 nm,直径约为20 nm,有望最大限度地提高钛植入材料的生物活性。     

有机电解液中TiO2纳米管阵列的制备及其光电性能

在氟化铵/丙三醇电解液中,采用恒压直流阳极氧化法制备TiO2纳米管阵列,并研究其在空气热处理过程中的结晶行为,最后将管阵列作为光阳极组装成染料敏化太阳能电池(DSSC),研究氧化时间和热处理温度对其光电性能的影响。结果表明:TiO2纳米管阵列的形成是一个随时间渐进演变的过程;随着氧化时间的延长,纳米管长度逐渐增大,当时间为70 h时,长度达到5μm左右;管阵列在空气中于400℃以下热处理后,由锐钛矿相构成,450和500℃热处理时,由锐钛矿相和金红石相构成,同时管阵列结构具有良好的高温稳定性。光电性能测试显示,20 V、70 h制备的TiO2纳米管阵列经450℃热处理后,组装成的染料敏化太阳能电池的(有效面积1 cm2)光电转换效率可达到0.989%。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。