有机薄膜晶体管钛/金电极的刻蚀工艺研究

采用感应耦合等离子体(ICP)干法刻蚀和湿法刻蚀的方法,分别刻蚀有机薄膜晶体管(OTFT)的钛/金薄膜电极。改变刻蚀的工艺条件,研究了不同的刻蚀工艺对OTFT器件性能的影响,并对刻蚀结果进行了比较与分析。结果表明,ICP干法刻蚀不适合用来刻蚀OTFT器件的钛/金电极,而湿法刻蚀工艺可用于刻蚀关键尺寸为5μm及其以上的钛/金电极,其最佳工艺条件分别是n(HF):n(HNO3):n(H2O)=1:1:5和n(KI):n(I2):n(H2O)=4:1:40。

Ti—1023钛合金的立铣问题

本文对Ti-1023钛合金的立铣进行了研究。测量了顺铣逆铣时的切削力,分析了铣削力、立铣刀挠度对精度的影响,推荐了Ti-1023钛合金立铣(铣周边、铣槽)的切削参数。

Tailoring the microenvironment of Ti sites in Ti-containing materials for synergizing with Au sites to boost propylene epoxidation

Au sites supported on Ti-containing materials(Au/Ti-containing catalyst)are currently considered as a promising catalyst for the propylene epoxidation owing to the synergistic effect that hydrogen peroxide species formed on Au sites diffuses to the Ti sites to form the Ti-hydroperoxo intermedi-ates and contributes to the formation of propylene oxide(PO).In principle,thermal treatment will significantly affect the chemical and physical structures of Ti-containing materials.Consequently,the synergy between tailored Ti sites with different surface properties and Au sites is highly expected to enhance the catalytic performance for the reaction.Herein,we systematically studied the intrinsic effects of different microenvironments around Ti sites on the PO adsorption/desorption and conversion,and then effectively improved the catalytic performance by tailoring the number of surface hydroxyl groups.The Ti^(Ⅵ) material with fewer hydroxyls stimulates a remarkable enhancement in PO selectivity and H_(2) efficiency compared to the Ti^(Ⅵ) material that possessed more hydroxyls,offering a 7-fold and 4-fold increase,respectively.As expected,the Ti^(Ⅵ+Ⅳ) and Ti^(Ⅳ) materials also exhibit a similar phenomenon to the Ti^(Ⅵ) materials through the same thermal treatment,which strongly supports that the Ti sites microenvironment is an important factor in suppressing PO con-version and enhancing catalytic performance.These insights could provide guidance for the rational preparation and optimization of Ti-containing materials synergizing with Au catalysts for propylene epoxidation.

A review on advances of high-throughput experimental technology for titanium alloys

Ti alloys,as leading lightweight and high-strength metallic materials,exhibit significant application potential in aerospace,marine engineering,biomedical,and other industries.However,the lack of fundamental understanding of the microstructure−property relationship results in prolonged research and development(R&D)cycles,hindering the optimization of the performance of Ti alloys.Recently,the advent of high-throughput experimental(HTE)technology has shown promise in facilitating the efficient and demand-driven development of next-generation Ti alloys.This work reviews the latest advancements in HTE technology for Ti alloys.The high-throughput preparation(HTP)techniques commonly used in the fabrication of Ti alloys are addressed,including diffusion multiple,additive manufacturing(AM),vapor deposition and others.The current applications of high-throughput characterization(HTC)techniques in Ti alloys are shown.Finally,the research achievements in HTE technology for Ti alloys are summarized and the challenges faced in their industrial application are discussed.

Phase transformation in titanium alloys:A review

Due to a series of exceptional properties,titanium and titanium alloys have received extensive attention in recent years.Different from other alloy systems,there are two allotropes and a sequence of metastable phases in titanium alloys.By summarizing the recent investigations,the phase transformation processes corresponding to the common phases and also some less reported phases are reviewed.For the phase transformation only involvingαandβphases,it can be divided intoβ→αtransformation and a reverse transformation.The former one has been demonstrated from the orientation relationship betweenαandβphases and the regulation ofαmorphology.For the latter transformation,the role of the stress has been discussed.In terms of the metastable phases,the mechanisms of phase formation and their effects on microstructure and mechanical properties have been discussed.Finally,some suggestions about the development of titanium alloys have been proposed.

A new rhombohedral phase and its 48 variants inβtitanium alloy

A new rhombohedral phase(termed R′)in a solution-aging-treated titanium alloy(Ti-4.5Al-6.5Mo-2Cr-2Nb-1V-1Sn-1Zr,wt.%)was identified.Its accurate Bravais lattice parameters were determined by a novel unit cell reconstruction method based on conventional selected-area electron diffraction(SAED)technique.The orientation relationship between R'phase and BCC phase was revealed.The results show that the R′phase is found to have 48crystallographically equivalent variants,resulting in rather complicated SAED patterns with high-order reflections.A series of in-situ SAED patterns were taken along both low-and high-index zone axes,and all weak and strong reflections arising from the 48 variants were properly explained and directly assigned with self-consistent Miller indices,confirming the presence of the rhombohedral phase.Additionally,some criteria were also proposed for evaluating the indexed results,which together with the Bravais lattice reconstruction method shed light on the microstructure characterization of even unknown phases in other alloys.

Ultrahigh strength and improved electrical conductivity in an aging strengthened copper alloy processed by combination of equal channel angular pressing and thermomechanical treatment

In this paper,equal channel angular pressing and thermomechanical treatment was employed to improve the strength and electrical conductivity of an aging strengthened Cu-Ti-Cr-Mg alloy,and the microstructure and properties of the alloy were investigated in detail.The results showed that the samples deformed by the combination of cryogenic equal channel angular pressing(ECAP)and rolling had good comprehensive properties after aging at 400℃.The tensile strength of the peak-aged and over-aged samples was 1120 MPa and 940 MPa,with their corresponding electrical conductivity of 14.7%IACS and 22.1%IACS,respectively.ECAP and cryogenic rolling introduced high density dislocations,leading to the inhibition of the softening effects and refinement of the grains.After a long time aging at 400℃,the alloy exhibited ultra-high strength with obvious increasing electrical conductivity.The high strength was attributed to the synergistic effect of work hardening,grain refinement strengthening and precipitation strengthening.The precipitation of a large amount of Ti atoms from the matrix led to the high electrical conductivity of the over-aged sample.

Effects of Ti-and Mg-bearing minerals on hydrothermal formation of hydroandradite

The effects of Ti-and Mg-bearing minerals on the crystal structure,morphology,particle size distribution,and formation mechanism of efficient desilication product of hydroandradite(HA)during hydrothermal conversion in a synthetic sodium aluminate solution were investigated via X-ray diffractometer,scanning electron microscope and particle size analyzer.During HA formation,anatase,rutile,and periclase dissolved in sodium aluminate solution engage in ion substitution reactions between Ti4+and Si4+,and between Mg^(2+)and Ca^(2+),respectively.However,dissolved hydromagnesite cannot enter into the HA.The content of HA after the hydrothermal reactions changes slightly with the increase of anatase and periclase contents,but it notably decreases with increased quantities of rutile and hydromagnesite.Ti-bearing minerals reduce the particle size and enhance the specific surface area of HA,whereas Mg-bearing minerals exert the opposite effect.The morphology of HA with Ti-and Mg-bearing minerals changes from spherical particles to flocculent structure and hexagonal plate-like particles.

Influence of anodization conditions on deposition of hydroxyapatite onα/βTi alloys for osseointegration:Atomic force microscopy analysis

Integrating titanium-based implants with the surrounding bone tissue remains challenging.This study aims to explore the impact of different anodization voltages(20−80 V)on the surface topography of two-phase(α/β)Ti alloys and to produce TiO_(2) films with enhanced bone formation abilities.Scanning electron microscopy coupled with energy dispersive spectroscopy(SEM−EDS)and atomic force microscopy(AFM)were applied to investigate the morphological,chemical,and surface topography of the prepared alloys and to confirm the growth of hydroxyapatite(HA)on their surfaces.Results disclosed that the surface roughness of TiO_(2) films formed on Ti−6Al−7Nb alloys was superior to that of Ti−6Al−4V alloys.Ti−6Al−7Nb alloy anodized at 80 V had the highest yields of HA after immersion in simulated body fluid with enhanced HA surface coverage.The developed HA layer had a mean thickness of(128.38±18.13)μm,suggesting its potential use as an orthopedic implantable material due to its promising bone integration and,hence,remarkable stability inside the human body.

In-situ Micro-CT analysis of deformation behavior in sandwich-structured meta-stable beta Ti−35Nb alloy

Beta Ti−35Nb sandwich-structured composites with various reinforcing layers were designed and produced using additive manufacturing(AM)to achieve a balance between light weight and high strength.The impact of reinforcing layers on the compressive deformation behavior of porous composites was investigated through micro-computed tomography(Micro-CT)and finite element method(FEM)analyses.The results indicate that the addition of reinforcement layers to sandwich structures can significantly enhance the compressive yield strength and energy absorption capacity of porous metal structures;Micro-CT in-situ observation shows that the strain of the porous structure without the reinforcing layer is concentrated in the middle region,while the strain of the porous structure with the reinforcing layer is uniformly distributed;FEM analysis reveals that the reinforcing layers can alter stress distribution and reduce stress concentration,thereby promoting uniform deformation of the porous structure.The addition of reinforcing layer increases the compressive yield strength of sandwich-structured composite materials by 124%under the condition of limited reduction of porosity,and the yield strength increases from 4.6 to 10.3 MPa.

Interfacial structure and mechanical properties of hot-roll bonded joints between titanium alloy and stainless steel using niobium interlayer

The hot-roll bonding was carried out in vacuum between titanium alloy and stainless steel using niobium interlayer. The interfacial structure and mechanical properties were analyzed. The results show that the plasticity of bonded joint is improved significantly. When the bonding temperature is 800 °C or 900 °C, there is not intermetallic layer at the interface between stainless steel and niobium. When the bonding temperature is 1000 °C or 1050 °C, Fe-Nb intermetallic layer forms at the interface. When the bonding temperature is 1050 °C, cracking occurs between stainless steel and intermetallic layer. The maximum strength of -417.5 MPa is obtained at the bonding temperature of 900 °C, the reduction of 25% and the rolling speed of 38 mm/s, and the tensile specimen fractures in the niobium interlayer with plastic fracture characteristics. When the hot-roll bonded transition joints were TIG welded with titanium alloy and stainless steel respectively, the tensile strength of the transition joints after TIG welding is -410.3 MPa, and the specimen fractures in the niobium interlayer.

Preparation of Ti-rich material from titanium slag by activation roasting followed by acid leaching

A method of activation roasting followed by acid leaching using titanium slag was introduced to prepare Ti-rich material. The effects of HaPO4 dosage, roasting temperature, and roasting time on TiO2 grade were investigated. A Ti-rich material containing 88.54% TiO2, 0.42% （CaO＋MgO） was obtained when finely ground titanium slag was roasted with 7.5% H3PO4 at 1000 ℃ for 2 h, followed by a two-stage leaching in boiling dilute sulfuric acid for 2 h. The XRD patterns show that the product is titanium dioxide with a rutile structure. Mechanism studies show that structures of anosovite solid solution and silicate minerals are destroyed in the roasting process. As a result, titanium components in titanium slag are transformed into TiO2 （futile） while impurities are transformed into acid-soluble phosphate and quartz.

Effects of second phases on mechanical properties and martensitic transformations of ECAPed TiNi and Ti-Mo based shape memory alloys

TiNi and Ti-based shape memory alloys were processed by equal channel angular pressing （ECAP） at 673-773 K along Bc route to obtain ultrafine grains for increasing the strength of parent phase and improving the functional properties. The effects of both thermodynamically stable and metastable second phases on the mechanical properties and martensitic transformations of these alloys were investigated. It is found that thermodynamically stable Ti2Ni phase has no effect on martensitic transformation and superelasticity of Ti-rich TiNi alloy, thermodynamically stable α phase is harmful for ductility of Ti-Mo-Nb-V-Al alloy, but metastable Ti3Ni4 phase is effective for R phase transformation, martensitic transformation and superelasticity of Ni-rich TiNi alloy. The mechanisms of the second phases on the martensitic transformations and mechanical properties were discussed.

Effects of nitrogen flux on microstructure and tribological properties of in-situ TiN coatings deposited on TC11 titanium alloy by electrospark deposition

In order to improve the tribological properties of titanium alloys,the in-situ TiN coatings were prepared by electrospark deposition（ESD） on the surface of TC11 titanium alloy.The effects of nitrogen flux on the microstructure and tribological properties of TiN coatings were investigated.The results show that the coating is relative thin when the nitrogen flux is small and mainly consists of Ti2N,α-Ti,Ti O and TiN phases,and the metastable phase of Ti2N is developed due to the rapid solidification of ESD.While in excessive nitrogen flux condition,many micro-cracks and holes might be generated in the coating.In moderate nitrogen flux,the coating is mainly composed of TiN phase,and is dense and uniform（50-55 μm）.The average hardness is HV0.2 1165.2,which is 3.4 times that of the TC11 substrate.The TiN coatings prepared in moderate nitrogen flux perform the best wear resistance.The wear loss of the coating is 0.4 mg,which is 2/9 that of the TC11 substrate.The main wear mechanisms of the coatings are micro-cutting wear accompanied by multi-plastic deformation wear.

Synthesis of Y_2O_3 particle enhanced Ni/TiC composite on TC4 Ti alloy by laser cladding

A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding. The phase component, microstructure, composition distribution and properties of the composite layer were investigated. The composite layer has graded microstructures and compositions, due to the fast melting followed by rapid solidification and cooling during laser cladding. The TiC powders are completely dissolved into the melted layer during melting and segregated as fine dendrites when solidified. The size of TiC dendrites decreases with increasing depth. Y2O3 fine particles distribute in the whole clad layer. The Y2O3 particle enhanced Ni/TiC composite layer has a quite uniform hardness along depth with a maximum value of HV1380, which is 4 times higher than the initial hardness. The wear resistance of the Ti alloy is significantly improved after laser cladding due to the high hardness of the composite coating.

Preparation of micro-nanostructure on titanium implants and its bioactivity

Surface modification of medical implants was considered as an effective method to improve the cellular behaviors and the integration of tissue onto materials. The micro-nanostructured surface on the titanium alloy was prepared by laser treatment and multiple acid etching. The surface morphologies of different titanium alloy substrates were characterized by scanning electron microscopy (SEM). The effects of micro-nanostructured surfaces on the cellular responses were investigated in vitro by observing hydroxyapatite formation, cell morphology and cell adhesion. The results indicate that the micro-sized structure promoted the adhesion and proliferation of cultured osteoblasts. Furthermore, the micro-nanostructured surface was more conducive to cell adhension stretching compared with the micro-structured surface. All results suggest that the micro-nanostructured surface improved the biocompatibility and integration of tissue onto titanium alloy implants.

Microstructure and mechanical properties of TC21 titanium alloy after heat treatment

Microstructure evolutions during different heat treatments and influence of microstmcture on mechanical properties of TC21 titanium alloy were investigated. The results indicate that the excellent mechanical properties can be obtained by adopting air cooling after forging followed by heat treatment of （900℃, 1 h, AC）＋（590 ℃, 4 h, AC）. Deformation in single β field produces pan-like prior fl grains, while annealing in single fl field produces equiaxed prior fl grains. Cooling rate after forging or annealing in single fl field and the subsequent annealing on the top of α＋β field determine the content and morphology of coarse a plates. During aging or the third annealing, fine secondary a plates precipitate. Both ultimate strength and yield strength decrease with the content increase of coarse a plates. Decreasing effective slip length and high crack propagation resistance increase the plasticity. The crisscross coarse a plates with large thickness are helpful to enhance the fracture toughness.

Hot deformation behavior and microstructural evolution of beta C titanium alloy in β phase field

The hot deformation behavior of beta C titanium alloy in β phase field was investigated by isothermal compression testson a Gleeble？3800 thermomechanical simulator. The constitutive equation describing the hot deformation behavior was obtained anda processing map was established at the true strain of 0.7. The microstructure was characterized by optical microscopy （OM）,scanning electron microscopy （SEM） and electron back-scattered diffraction （EBSD） technique. The results show that the flow stressincreases with increasing strain rates, and decreases with increasing experimental temperatures. The calculated apparent activationenergy （167 kJ/mol） is close to that of self-diffusion in β titanium. The processing map and microstructure observation exhibit adynamic recrystallization domain in the temperature range of 900-1000 ℃ and strain rate range of 0.1-1 s^-1. An instability regionexists when the strain rate is higher than 1.7 s^-1. The microstructure of beta C titanium alloy can be optimized by proper heattreatments after the deformation in the dynamic recrystallization domain.

Microstructure characterization and mechanical properties of TC4-DT titanium alloy after thermomechanical treatment

Influence of thermomechanical treatments （mill annealing, duplex annealing, solution treatment plus aging and triple annealing） on microstructures and mechanical properties of TC4-DT titanium alloy was investigated. Results showed that thermomechanical treatments had a significant influence on the microstructure parameters and higher annealing and aging temperature and lower cooling rate led to the decrease of the volume fraction of primaryαand the size of prior-βand the increase of the width of grain boundary αand secondary α. The highest strength was obtained by solution treatment and aging due to a large amount of transformedβand finer grain boundaryαand secondaryαat the expense of slight decrease of elongation and the ultimate strength, yield strength, elongation, reduction of area were 1100 MPa, 1030 MPa, 13%and 53%separately. A good combination of strength and ductility has been obtained by duplex annealing with the above values 940 MPa, 887.5 MPa, 15%and 51%respectively. Analysis between microstructure parameters and tensile properties showed that with the volume fraction of transformedβphase and the prior-βgrain size increasing, the ultimate strength, yield strength and reduction of area increased, but the elongation decreased. While the width of grain boundary α and secondary α showed a contrary effect on the tensile properties. Elimination of grain boundaryαas well as small prior-βgrain size can also improve ductility.

Influence of high-speed milling parameter on 3D surface topography and fatigue behavior of TB6 titanium alloy

High-speed milling of titanium alloys is widely used in aviation and aerospace industries for its high efficiency and good quality.In order to optimize the machining parameters in high-speed milling TB6 titanium alloy,experiments of high-speed milling and fatigue were conducted to investigate the effect of parameters on 3D surface topography and fatigue life.Based on the fatigue fracture,the effect mechanism of surface topography on the fatigue crack initiation was proposed.The experiment results show that when the milling speed ranged from 100 m/min to 140 m/min,and the feed per tooth ranged from 0.02 mm/z to 0.06 mm/z,the obtained surface roughness were within the limit（0.8 μm）.Fatigue life decreased sharply with the increase of surface equivalent stress concentration factor.The average error of fatigue life between the established model and the experimental results was 6.25%.The fatigue cracks nucleated at the intersection edge of machined surface.