Surface characteristics of titanium–silver alloys in artificial saliva

Titanium and its alloys are widely used in biomedical and dental fields because of their excellent corrosion resistance and biocompatibility. It is well known that titanium is protected from corrosion because of the stability of the passive film that controls and determines the corrosion resistance and biocompatibility of titanium and its alloys. The purpose of this study was to evaluate the electrochemical properties of titanium–silver alloys and the surface characteristics of passive film in artificial saliva. We designed titanium–silver alloys with silver contents ranging from 0 to 5 at.%, in 1% increments. These alloys were arc‐melted, homogenized, hot‐rolled to 2 mm thickness, and finally solution heat‐treated for 1 h and quenched. Potentiostatic testing was performed, and the open circuit potentials of the alloys were measured in artificial saliva, at 37 °C. The passive films of the titanium–silver alloys were analyzed via XPS. Titanium–silver alloys maintained low current density and showed stable passive region and also had high open circuit potential as compared with pure titanium. The open circuit potential of titanium–silver alloys increased as silver addition increased. With regard to the fraction of oxygen species, a component of over 80% was found to be comprised of oxide. Therefore, the titanium surface mainly consisted of titanium oxide and, on the titanium–silver alloys, this film was composed of TiO₂, Ti₂O₃, and TiO. As silver content increased, the TiO₂ fraction also increased, as did the thickness of the titanium oxide layer formed. Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of rapid solidification on heat capacities of Al-Sr alloys

Heat capacities of both the ingot-like and melt-spun Al-Sr alloys have been measured through the temperature range 373 to 1060 K using differential scanning calorimetry. The experimental results show that rapid solidification has a slight effect on the temperature dependence of the heat capacities of the Al-Sr alloys. The heat capacities of the melt-spun Al-Sr alloys increase more slowly than those of the ingot-like alloys with increasing temperature from 373 to 900 K. Furthermore, the effect of rapid solidification on the heat capacities becomes more obvious with increasing Sr concentration in the Al-Sr alloys. The data of the heat capacities between 373 and 900 K have been fitted with the least square method and a linear dependence on temperature was assumed for that temperature range. This revised version was published online in July 2006 with corrections to the Cover Date.     

稀土Invar合金的热化学性质研究

Invar合金是一类在正常温度范围内具有膨胀性随温度变化很小甚至不变之特性的合金材料，对IllV。合金有多种模型解释，其中焰和热容是最重要的参数之一［‘，’］在稀土IllV。I合金中，只有L贝；。B的低温（T＜300K）热容作过报导问．作为系统研究稀土＊v。r合金工作、‘」的部分内容，本文报导含稀土InV。I合金REZFe14B和REFe12。V。的热化学性质研究结果，以便为选择最佳稀土Invar合金提供科学依据．1实验1·1合金制备所制备的合金为Y2F214B、SmFIDVZ、YFe10VZ、L22Fe14B、C42Fe14B、NdZFe14B、Sin。Fe。。B和NdFel…     

Anodic film formation on binary Al?Mg and Al?Ti alloys in nitric acid

Nitric acid is commonly used for surface treatments of aluminium alloys. It is used to clean the surfaces after alkaline etching; it has application in chemical polishing and is also used for electrograining. The majority of these treatments undergo the application of anodic polarisation that results in formation of anodic oxide film. However, little is known about the behaviour of aluminium containing magnesium or titanium in solid solution under such conditions. To reveal the effects of magnesium and titanium alloying additions on anodic film formation in nitric acid, Al‐1800 ppm Mg and Al‐800 ppm Ti alloys were investigated. It was found that porous alumina film developed on the surfaces with reduced efficiency of 40%, due to the reactive nature of nitric acid to alumina. The presence of magnesium and titanium in aluminium had little influence on the efficiency of film growth, as confirmed by the relatively similar thicknesses of oxide formed on binary alloys and aluminium. However, incorporation of magnesium ions into the alumina film led to development of a high‐population density of localised voids near the alloy/film interface. An increased titanium content was found in the film regions close to the alloy/film interface, indicating its oxidation. Copyright © 2009 John Wiley & Sons, Ltd.     

DMTA study of a nickel-titanium wire

The nickel-titanium alloys are usually known as Shape Memory alloys because of their ability to return to some previously defined shape or size when subjected to the appropriate thermal procedure. Mechanical properties of a nickel titanium wire were investigated by DMTA using cylindrical tension mode. The Young"s modulus, the maximum strain and residual deformation have been calculated. Recovery of previously deformed samples was observed in constant stress temperature ramp tests. Relaxation stress behaviour at temperatures above the austenitic transformation has been studied. The strain and frequency ranges of linear response have been determined by dynamic experiments. Strain amplitude of 0.1% and frequency of 1 Hz have been chosen for the temperature ramp dynamic experiments. A big change between 65 and 95°C is observed in the storage modulus. The values of E' at temperatures below and above the transition are essentially constant. Finally, the effects of the frequency at different temperatures have been examined. This revised version was published online in July 2006 with corrections to the Cover Date.     

Single-Phase Polymer Alloys of Polyvinyl Chloride and New Polymers

Polymer alloying is acquiring ever increasing significance for the modification of polymeric materials. Polymer alloys are defined by their phase character, which in turn is determined by the mutual compatibility or incompatibility of the components. Suitable techniques for the analysis of the phase character include, inter alia, dynamic-mechanical methods, according to which a polymer alloy may be considered in a simplified manner as single-phase when only one glass transition is observed, even if it extends over a broader temperature range than in the case of the pure components. Aliphatic (polyester)-polycarbonates and tetramethylbisphenol-A polycarbonate are new, PVC-compatible, polymer modifiers. The (polyester)-polycarbonates (from adipic acid, hexane-1,6-diol, neopentanediol, and diphenyl carbonate) yield with PVC single-phase alloys that at temperatures above the glass transitions of the mixture display the characteristics of soft PVC and that are tough far below this temperature. The special high-temperature properties of the resin-like tetramethylbisphenol-A polycarbonate permits the preparation of alloys with increased dimensional stability under heat (higher deflection temperatures under load).     

LaNi_(5-x)M_x高温氢化的歧化行为

采用X射线衍射、差热分析及电化学方法 ,研究了吸氢合金LaNi5-xMx(M =Mn ,Co,Fe,Cr,Al)在高温氢化反应时的歧化行为及其反应产物的电化学性能。LaNi5-xMx 在 2 5MPa氢压和 550℃以上保温一定时间后可发生明显的歧化反应 ,并析出纳米相镍。歧化反应的程度与加热温度、时间、第三组元M及合金的生成焓关系密切。电化学交换电流密度测定表明 ,经歧化反应得到的含纳米相镍的复相组织与原始合金组织相比具有较高的吸放氢电催化活性。     

微量钆对Ag-Au合金再结晶行为的影响

采用示差扫描量热,金相,透射电子显微镜及硬度测量等方法研究了微量Ｇｄ对互溶的Ａｇ－Ａｕ系合金再结晶行为的影响。结果表明,在Ａｇ－Ａｕ合金中加入微量Ｇｄ后,在合金内形成含Ｇｄ后,在合金内形成含Ｇｄ的第二相颗粒,弥散分布于基体中,显著提高合金的再结晶温度,并使晶粒细化。     

Glass Transition Behavior in Se-Rich Ge-Se Alloys

Differential scanning calorimetry (DSC) was utilized to study the behavior of six Ge-Se glasses containing 0, 5, 10, 15, 17.5 and 20 at.% Ge during the glass transition. These alloys readily form glasses and can be prepared by quenching in air. Moreover, their behavior depends greatly on the composition. This work reveals that two additional properties must be considered: the variation in the glass transition temperature and different structural relaxation. The quantity used to quantify the relaxation was the enthalpy relaxation as this measures the heat lost by the glass during annealing. Given the complexity of the relaxation process, the experimental results were analysed by means of the empirical Kohlrausch-Williams-Watts relaxation model. This revised version was published online in July 2006 with corrections to the Cover Date.     

石墨烯对镍钛形状记忆合金耐腐蚀性能的影响

利用化学气相沉积法在镍钛形状记忆合金表面原位生长出石墨烯,拟提高镍钛形状记忆合金的抗腐蚀性能。通过X射线光电子能谱、拉曼光谱与扫描电镜等手段对其表征,分析石墨烯修饰后的合金表面结构和形貌。在人工唾液环境中探究了石墨烯对镍钛形状记忆合金的腐蚀速率、细胞毒性和金属释放的影响。结果表明,石墨烯在金属基体和腐蚀介质之间可以起到物理屏蔽作用,可明显地降低金属基体发生腐蚀的速率,对镍钛合金具有较强的保护能力。     

Dependency of thermal and electrical conductivity on temperature and composition of Sn in Pb–Sn alloys

The variations of thermal conductivity with temperature for Pb–Sn alloys were measured using a radial heat flow apparatus. The variations of electrical conductivity with the temperature for same alloys were determined from the Wiedemann–Franz law by using the measured values of thermal conductivity. According to present experimental results, the thermal and electrical conductivity of Pb–Sn alloys linearly decrease with increasing temperature but exponentially increase with increasing the composition of Sn. The enthalpy of fusion and the change of specific heat for Pb–Sn alloys were also determined by means of differential scanning calorimeter (DSC) from heating trace during the transformation from eutectic liquid to eutectic solid.     

La2O3对钛合金表面镍基喷焊涂层组织和性能的影响

采用火焰喷焊技术在钛合金基体上制备了不加La2O3和加4％(质量分数)La2O3两种镍基涂层，分析了它们的显微组织、合金元素的扩散、显微硬度以及耐磨性能。结果表明：La2O3的加人，改善了涂层合金的流动性和显微组织的均匀性，并使涂层与基体的熔合更加明显，结合性能得到进一步提高；虽然一定程度上减弱了基体Ti元素对喷焊层的强化作用，使表层显微硬度略有下降，但磨损失重却较未加La2O3的喷焊涂层下降了20％。     

Surface properties of metal alloys used in aviation after plasma treatment

The metal alloys: aluminum AMS 4037, 4041, 4049, carbon steel AMS 5045, titanium alloy AMS 4911 and cadmium steel used in aviation were treated by air and argon plasmas. For their activation, low pressure plasma was used. Surface treatment caused a significant increase of wettability due to the increasing surface roughness and introduction of polar functional groups onto the surface. Changes of surface properties are reflected by the value of electron donor parameter of apparent surface energy. Copyright © 2017 John Wiley & Sons, Ltd.     

Preparation of Mg-Li alloys by electrolysis in molten salt at low temperature

A new technology for preparation of low cost Mg-Li alloys was studied. The alloys were prepared by electrolysis in molten LiCl-KCl (weight ratio is 1:1) electrolyte with Mg rod severing as the consumed cathode. Main factors that affect current efficiency were investigated, and optimal electrolysis parameters were obtained. Mg-Li alloys with low lithium content (about 25%) were prepared by the unique method of a higher post-thermal treatment temperature after electrolysis at low temperature. The results showed that the electrolysis can be carried out at low temperature, which resulted in reducing preparation cost due to energy saving.The new technology for the preparation of Mg-Li alloy by electrolysis in molten salt was proved to be feasible.     

A direct electrochemical route from ilmenite to hydrogen-storage ferrotitanium alloys

An unrecognised but predictable need for a hydrogen-supported society is tens or even hundreds of million tonnes of hydrogen-storage materials, and thus challenges existing technologies in terms of resource and economical realities. Ilmenite is an abundant mineral, and ferrotitanium alloys are among the earliest known hydrogen-storage materials. At present, industrial production of ferrotitanium alloys goes through separate extraction of individual metals, followed by a multistep arc-melting process. In particular, the extraction of titanium from ilmenite is highly energy intensive and tedious, accounting for titanium's high market price and restricted uses. This article reports the electrochemical synthesis of various ferrotitanium alloy powders directly from solid ilmenite in molten calcium chloride. More importantly, it demonstrates, for the first time, that such produced alloy powders can be used without further treatment for hydrogen storage and perform comparably with or better than similar products by means of other methods, but cost just a fraction.     

Automatic equipment with improved performances (ATD and DSC) in shape memory alloys studies

We describe an experimental set-up of high resolution thermal analysis (HRTA) activated by Peltier effect and computer-controlled by the signal processing that allows a high resolution programming of the temperature and a reproducibility better than ±0.01 deg.The basic equipment is suitable for studying the behaviour of the shape memory alloys (i.e. Cu based alloys). We also describe the applications of the system, which allows to build up a calorimetric system (heat flux or conduction calorimetry) (resolution 1.5 W) or a stress-strain-temperature system of 20 N of maximum charge (resolution around 1 mN and 0.1 m.CICYT projects MAT89-407-C03-01 and PETRI-90 are gratefully acknowledged. H. T. acknowledges the DGICYT (sabbatic program) for financial aid in international cooperation. The enlightening discussions with Dr. F. C. Lovey (Centro Atomico Bariloche - Argentina) are also acknowledged.     

Ordre chimique dans les alliages metalliques liquides

Due to improvements of high temperature calorimetry, the quantity of liquid alloys showing large negative departures from ideality increased strongly during the last decades. Such a behaviour is now explained by the occurence of chemical short-range order (CSRO), the stoichiometry of which is often elucidated from direct structural determinations as well as from modelization of the thermodynamic functions. In some extreme cases, the destruction of CSRO by increasing temperature lead to a genuine second order transition. The short rewiev of experimental results concerning the variation of physical properties of some liquid alloysvs. temperature and concentration agrees well with CSRO. Some examples of structural determination of CSRO in metallic melts are given. Finally, links between CSRO and phase diagrams and between CSRO and glass-forming ability are also examined.     

Kinetics and Thermodynamics of the Absorption of Hydrogen in β-titanium Alloys

A thermogravimetric method was applied to study the hydrogen uptake in the near-β-titanium alloy Ti 10 2 3 and the metastable β-titanium alloy Ti 21S. The tests were performed in H₂-He gas mixtures with various partial pressures of H₂ at temperatures between 600 and 800°C. Basic findings such as the decreasing solubility of H₂ with increasing temperature could be verified, and first information on the effects of surface conditions was gained. Thus, it could be shown that, despite the low atomic mass of hydrogen, thermogravimetry is an appropriate tool for investigation of the H₂/metal interactions of titanium alloys. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ti-V基储氢合金及其氢化物的物相结构与组分优化设计

Ti-V基储氢合金在室温、常压下即可表现出良好的储氢特性,且质量储氢容量明显高于传统AB₅型储氢合金,从而在氢气的精制和回收、运输和储存及热泵等方面有较早的应用。 此外,在混合气体分离、核反应堆中处理氢的同位素、镍氢电池及燃料电池负极材料等方面也得到了广泛的研究与关注。 基于目前Ti-V基储氢合金的研究现状,概述了该类合金的优势、限制性因素(包括成因)及改性手段。 此外,为了进一步理解Ti-V基合金储氢机理、构建合金组分与储氢特性之间的对应关系,本工作重点围绕Ti-V基储氢合金及其氢化物的结构、组分优化设计展开综述,并对其未来研究方向做出展望。