High temperature oxidation behavior of (Ti, Al)N coating deposited by arc ion plating

(Ti, Al)N gradient nano-coating was deposited on the surface of 1Cr11Ni2W2MoV stainless steel by the MTP-8-800 arc ion plating equipment. And the oxidation performance at high temperature for 500h was tested under the condition of the surrounding air temperature 700℃. The test results show that, because of the structural features of the （Ti, Al）N coating, the coating becomes the compact and continuous Al2O3 film, which can protect the basis material effectively in the process of the high temperature oxidizing. The oxidation kinetics of the coating accord with parabolic law.

Influence of Temperature on Nitrogen Ion Implantation of Ti6Al4V Alloy

in order to achieve increased layer thickness, and wearing resistance, enhanced ion implantation with nitrogen has been carried out at temperatures of 100, 200, 400, and 600℃ with a dose of 4x 1018 ions' cm-2. Using the Plasma Source ion Implantation (PSII) device, specimens of Ti6Al4V alloy were implanted at elevated temperatures, using the ion flux as the heating source. Auger Electron Spectroscopy (AES), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), micro-hardness measurements and pin-on-disk wearing tester were utilized to evaluate the surface property improvements. The thickness of the implanted layer increased by about an order of magnitude when the temperature was elevated from 100 to 600℃. Higher surface hardness and wearing resistance was also obtained in implantation under higher temperature. XRD image showed the presence of titanium nitrides on the implanted surface.

Electrochemical oxidation of aniline by a novel Ti/TiO_xH_y/Sb-SnO_2 electrode

Electrochemical oxidation of aniline in aqueous solution was investigated over a novel Ti/TiOxHy/Sb-SnO2 electrode prepared by the electrodeposition method.Scanning electron microscopy,X-ray diffraction,and electrochemical measurements were used to characterize its morphology,crystal structure,and electrochemical properties.Removal of aniline by the Ti/TiOxHy/Sb-SnO2electrode was investigated by ultraviolet-Visible spectroscopy and chemical oxygen demand（COD）analysis under different conditions,including current densities,initial concentrations of aniline,pH values,concentrations of chloride ions,and types of reactor.It was found that a higher current density,a lower initial concentration of aniline,an acidic solution,the presence of chloride ions（0.2wt%NaCl）,and a three-dimensional（3D） reactor promoted the removal efficiency of aniline.Electrochemical degradation of aniline followed pseudo-first-order kinetics.The aniline（200 mL of 100mg·L-（-1）） and COD removal efficiencies reached 100%and 73.5%,respectively,at a current density of 20 mA·cm-（-2）,pH of 7.0,and supporting electrolyte of 0.5 wt%Na2SO4 after 2 h electrolysis in a 3D reactor.These results show that aniline can be significantly removed on the Ti/TiOxHy/Sb-SnO2electrode,which provides an efficient way for elimination of aniline from aqueous solution.

Tribological behavior of different films on Ti-6Al-4V alloy prepared by plasma-based ion implantation

The tribological behaviors of TiN coating and TiN+TiC+Ti(C, N)/diamond like carbon (DLC), TiN/DLC, TiC/DLC multilayers on Ti 6Al 4V alloy prepared by plasma based ion implantation (PBII) were compared. Under the test conditions of counterbody AISI 52100, load 1 N and speed 0.05 m/s, the tribological properties of the alloy are improved by these films in the order of TiN, TiC/DLC, TiN/DLC and TiN+TiC+Ti(C,N)/DLC. Tribological behavior is affected by the conditions of surface modification and triboexperiments. The appearance of “peaks” in the wear dynamic resistance profiles may be due or correspond to the process of formation and breaking apart of transition films. The breakthrough of the DLC coated samples may start from partially wearing out, and end with joining piece dilamination. There are transition films on all counterbodies AISI 52100. When AISI 52100 counterbody is changed to Ti 6Al 4V, the wear of most modified samples is changed from only disc to both disc and ball abrasive dominated.

NiCo-LDH/Ti3C2 MXene hybrid materials for lithium ion battery with high-rate capability and long cycle life

Nickel/cobalt-layered double hydroxides(Ni Co-LDH) have been attracted increasing interest in the applications of anode materials for lithium ion battery(LIB), but the low cycle stability and rate performance are still limited its practice applications. To achieve high performance LIB, the surface-confined strategy has been applied to design and fabricate a new anode material of NiCo-LDH nanosheet anchored on the surface of Ti3C2 MXene(Ni Co-LDH/Ti3C2). The ultra-thin, bended and wrinkled α-phase crystal with an interlayer spacing of 8.1 ? can arrange on the conductive substrates Ti3C2 MXene directly, resulting in high electrolyte diffusion ability and low internal resistance. Furthermore, chemical bond interactions between the highly conductive Ti3C2 MXene and Ni Co-LDH nanosheets can greatly increase the ion and electron transport and reduce the volume expansion of NiCo-LDH during Li ion intercalation. As expected,the discharge capacity of 562 m Ah g-1 at 5.0 A g-1 for 800 cycles without degradation can be achieved,rate capability and cycle performance are better than that of NiCo-LDH(~100 mAh g-1). Furthermore, the density function theory(DFT) calculations were performed to demonstrate that Ni Co-LDH/Ti3C2 system can be used as a highly desirable and promising anode material for lithium ion battery.

Effect of N-ion implantation and diamond-like carbon coating on fretting wear behaviors of Ti6Al7Nb in artificial saliva

The tribology behaviors of Ti6Al7Nb,its alloy with N-ion implantation,and its alloy with diamond-like carbon(DLC)coating were investigated in artificial saliva.Fretting wear tests of untreated,N-ion implanted and DLC coated Ti6Al7Nb alloys plate against a Si3N4ball were carried out on a reciprocating sliding fretting wear test rig.Based on the analysis of X-ray diffraction,Raman spectroscopy,3-D profiler,SEM morphologies and frictional kinetics behavior analysis,the damage behavior of surface modification layer was discussed in detail.The results indicated that the fretting wear behavior of Ti6Al7Nb alloy with N-ion implantation was increased with the dose increase of the implanted nitrogen ions.Moreover,the DLC-coated Ti6Al7Nb alloy with low ion implantation could improve the fretting wear behavior greatly.In addition,the Ti6Al7Nb with DLC coating had better ncorrosion resistance due to the special compact structure.All results suggested that the Ti6Al7Nb with DLC coating had better wear resistance than that with N-ion implantation in artificial saliva.

Rare earth doped CaCu_3Ti_4O_(12) electronic ceramics for high frequency applications

Ca1-xRxCu3Ti4O12(R=La,Y,Gd;x=0,0.1,0.2,0.3) electronic ceramics were fabricated by conventional solid-state reaction method.The microstructure and dielectric properties as well as impedance behavior were carefully investigated.XRD results showed that the secondary phases with the general formula R2Ti2O7 existed at grain boundaries of rare earth doped ceramics,which inhibited abnormal grain growth.The dielectric constant decreased from 4×105 in pure CaCu3Ti4O12(CCTO) ceramics to 2×103 with rare earth doping....

Preparation and characterization of SnO_2-Li_4Ti_5O_(12) composite by sol-gel technique

SnO2-Li4Ti5O12 was prepared by sol-gel method using tin tetrachloride,lithium acetate,tetrabutylorthotitanate and aqueous ammonia as starting materials.The composite was characterized by thermogravimertric(TG)analysis and differential thermal analysis(DTA),X-ray diffractometry(XRD)and transmission electron microscopy(TEM)combined with electrochemical tests.The results show that SnO2-Li4Ti5O12 composite derived by sol-gel technique is a nanocomposite with core-shell structure, and the amorphous Li4Ti5O12 layer with 20?40 nm in thickness is coated on the surface of SnO2 particles.Electrochemical tests show that SnO2-Li4Ti5O12 composite delivers a reversible capacity of 688.7 mA·h/g at 0.1C and 93.4%of that is retained after 60 cycles at 0.2C.The amorphous Li4Ti5O12 in composite can accommodate the volume change of SnO2 electrode and prevent the small and active Sn particles from aggregating into larger and inactive Sn clusters during the cycling effectively,and enhance the cycling stability of SnO2 electrode significantly.

Structure and Tribological Property of TiBN Nanocomposite Multilayer Synthesized by Ti-BN Composite Cathode Plasma Immersion Ion Implantation and Deposition

A Ti-BN complex cathode is made from Ti and h-BN powders by the powder metallurgy technology, and TiBN coating is obtained by plasma immersion ion implantation and deposition with this Ti-BN composite cathode. The TiBN coating shows a self-forming multilayered nanocomposite structure while with relative uniform elemental distributions. High resolution transmission electron microscopy images reveal that the multilayered structure is derived from different grain sizes in the nanocomposite. Due to the existence of h-BN phase, the friction coefficient of the coating is about 0.25.

Improvement of tribological behavior of a Ti-Al-V alloy by nitrogen ion implantation

The tribological properties especially wear and hardness of a Ti-Al-V alloy with nitrogen implantation (energy 60 keV) were investigated. The implantation was carried out at fluences range from 1×1016 to 4×1017 ions/cm2. Glancing angle X-ray diffraction (GAXRD) and X-ray photoelectron spectroscopy (XPS) analyses were performed to obtain surface characterization of the implanted sample. The unimplanted and implanted samples were also annealed at 600 ℃ in order to understand the influence of annealing on the tribological properties of Ti-Al-V. The hardness shows significant improvement at the higher fluence. After annealing at 600 ℃, the friction coefficient exhibits a relative decrease for the nitrogen-implanted samples. In addition, the wear rates of the implanted samples exhibits a great decrease after annealing at 600 ℃. Nature of the surface and reason for the variation and improvement in wear resistance were discussed in detail.

Structure and electrochemical properties of Li(Ni_(0.5)Mn_(0.5))_(1-x)TixO_2 prepared by one-step solid state reaction

The layered compound Li(Ni0.5Mn0.5)1?xTixO2 powders were prepared with Ni(OH)2,MnCO3,Li2CO3 and TiO2 by one-step solid state reaction.The effect of doping Ti on the structure and electrochemical properties was studied.The XRD results indicate that the powders with 0≤x≤0.05 have good layered structure and trace of impurity appears in the samples with x≥0.1.The SEM photographs show that the particle size distributes homogeneously and the sample with x=0.15 has larger particle size than other samples.The charge-discharge tests show that Li(Ni0.5Mn0.5)0.95Ti0.05O2 synthesized at 800 ℃ for 36 h exhibits good electrochemical properties.It firstly delivers 173 mA·h/g and maintains 90% of the initial discharge capacity after 30 cycles.The cyclic voltammetry and differential capacity vs voltage curves show that the major oxidation and reduction peaks are around 3.95 V and 3.75 V,respectively,assigned to Ni2+/Ni4+ oxidation-reduction process.A weak peak around 4.5 V is found during the oxidation process in the first cycle,which can be regarded as the main reason of the large drop of discharge capacity in the initial cycle.

Understanding the roles of Ti on the structure and electrochemical performances of Li2Ru1-xTixO3 cathode materials for Li-ion batteries

The lattice doping has been widely used to improve the electrochemical performances of Li-rich cathode materials but the roles of the introduced foreign atoms are still not very clear.Herein,a series of Li2Ru1-xTixO3 solid solutions have been synthesized and the roles of Ti doping on the structural and electrochemical properties of Li2RuO3 have been comprehensively investigated.The Rietveld refinement exhibits that the interlayer spacing gradually shortens with increasing Ti content.This shrinkage is favorable to the layered structure stability but increases the lithium diffusion barrier.Galvanostatic measurements show that Li2Ru0.8Ti0.2O3 possesses the best cyclability with 196.9 and 196.1 m Ah g-1for charge and discharge capacity retaining after 90 cycles,respectively.Cyclic voltammetry scanning indicates that Ti dopant promotes the formation of more peroxo-or superoxo-like species but reduces the initial coulumbic efficiency.Results of electrochemical impedance spectroscopy display that Ti doping reduces the charge transfer impedance,which facilitates the lithium-ion diffusion across the electrolyteelectrode interface and improves the electronic conductivity.Li2Ru0.8Ti0.2O3exhibits the best electrochemical performance owing to the balance among all the factors discussed above.This study also offers some new insights into optimizing the electrochemical performances of Li-rich cathode materials through the lattice doping.

Influences of nitrogen flow rate on the structures and properties of Ti and N co-doped diamond-like carbon films deposited by arc ion plating

In this paper, Ti-C-N nanocomposite films are deposited under different nitrogen flow rates by pulsed bias arc ion plating using Ti and graphite targets in the Ar/N2 mixture gas. The surface morphologies, compositions, microstructures, and mechanical properties of the Ti-C-N films are investigated systematically by field emission scanning electron mi- croscopy （FE-SEM）, x-ray photoelectron spectroscopy （XPS）, grazing incident x-ray diffraction （GIXRD）, Raman spectra, and nano-indentation. The results show that the nanocrystalline Ti（C,N） phase precipitates in the film from GIXRD and XPS analysis, and Raman spectra prove the presence of diamond-like carbon, indicating the formation of nanocomposite film with microstructures comprising nanocrystalline Ti（C,N） phase embedded into a diamond-like matrix. The nitrogen flow rate has a significant effect on the composition, structure, and properties of the film. The nano-hardness and elastic modulus first increase and then decrease as nitrogen flow rate increases, reaching a maximum of 34.3 GPa and 383.2 GPa, at a nitrogen flow rate of 90 sccm, respectively.

Composition and Structure of Ti-6Al-4V Alloy Plasma-based Ion Implanted with Nitrogen

The composition and structure of Ti 6Al 4V alloy plasma based ion implanted with nitrogen was investigated.The nitrogen depth distribution shows more antiballistic with distribution peak heightened with increased implantation time(dose),and more like a parabola at the low implantation pulse voltage.When implantation pulse voltage is increased,the implantation depth increased with the nitrogen distribution peak being deepened,widened and lowered somewhat.TiN,TiN+Ti 2N,or Ti 2N second phases were formed in the implanted layer.The relative percentage of nitrogen content in the form of TiN increases when going deeper into the implanted(TiN formed) layer.The increase of implantation pulse width and/or time is favourable for the formation of TiN rather than Ti 2N.It is unfavourable for formation of any nitrides when implantation pulse voltage is decreased to 30kV or less.Tiny crystalline particles (made mainly of Ti 2N and a smaller percentage of TiO 2 phases) of regular shapes such as triangle and tetragon, etc .(about 20 nm) are found distrbuted dispersively in the near surface region of samples implanted at the high implantation pulse voltage (75kV).

Plasma-based ion implantation of nitrogen into Ti-6Al-4V: effect of implantation time and pre-or post-implantation aging on nitrogen distribution and microhardness

Presents the investigation of the effect of implantation time and pre or post implantation aging on nitrogen distribution and microhardness with the following findings: the colour of the surface is modified after implantation and it gets darker with the increase of implantation time, and is not affected by pre or post implantation aging; for every implanted sample, a peak is found in the near surface region of the nitrogen concentration depth profile determined by X ray photoelectron spectroscopy (XPS); The position of the peak is not affected by implantation time and pre or post implantation aging used; With the increase of implantation time, the surface nitrogen concentration increases, and the peak is heightened, but the speed of heightening decreases; The surface structure formed after the implantation may be more unstable and more readily oxidized in its subsequent exposure to air; The implanted samples can be protected against oxidation by immersing them in pure alcohol; and the immersion causes the surface nitrogen concentration to increase somewhat and the surface oxygen concentration to decrease in comparison with the exposure to air. The implanted samples exhibit higher hardness improvement factor especially at low plastic penetrations. The exposure to air causes the hardness improvement factor to increase. As the implantation time is increased, the hardness improvement factor increases (but at a decreased speed). Over long implantation time can induce a softening process because the hardness improvement effects are then unable to follow the effect of strength loss.

A STUDY ON Ti ELECTRODE MODIFIED BY NICKEL ION BEANS

The reduction of H^+ on Ti electrodes which were treated by implanting nickel ions and thermodiffusing in vacuum has been studied.The calytic activity of the afore- mentioned electroes for H^+ reduction is much higher than that of the untreated Ti electrodes.

Effect of Molybdate Ions on the Corrosion Behaviour of Ti Alloys

Titanium alloys are extensively used in power, chemical and petroleum industries as constructional materials for vessels and heat transfer tubes. Moreover they are candidate materials for nuclear waste disposal. These alloys have superior resistance to localized forms of corrosion compared to stainless steels and Ni-base alloys. However, this resistance is not as remarkable in crevice corrosion conditions in some aggressive media. Electrochemical corrosion tests were conducted on two ASTM Ti grades namely, Ti-2 and Ti-12 in extremely low pH acidic environment. Results indicated that Ti-2 has less resistance to both general and crevice corrosion attack than Ti-12. Both alloys possess better resistance to general corrosion than to crevice corrosion. Also, results showed that the molybdate addition improves remarkably the resistance of Ti-2 to both types of attack. The increase of molybdate ions concentration from 0.03 mol/L to 0.15 mol/L made Ti-2 to be as resistant as, or somewhat higher than, Ti-12. The elecrochemical findings were further supplemented by optical examination of the corroded surface.

SURFACE ANALYSES OF NITROGEN ION IMPLANTED Ti6Ai4V ALLOY

The techniques for surface analysis including AES,XPS and SIMS were employed to study the chemical composition and bond valence of nitrogen ion implanted surface of surgical implantation service alloy Ti6Al4V.The depth of implanted nitrogen ions and the sputtering rate of argon beams were determined using a profilometer.It was found that the combination of injected nitrogen ions with titanium resulted in the formation of hard TiN particles and the profile of nitrogen concentration approximately displayed gaussian distribution.The total depth of implanted nitrogen is about 350 nm and its maximum concentration appears in the depth of about 140 nm from the surface,in which the concentration ratio of nitrogen to titanium may be up to 1.1.

In situ polymerization preparation and characterization of Li_4Ti_5O_(12)-polyaniline anode material

Li4Ti5O12 powders were prepared by so-gel method using tetrabutyl titanate,lithium acetate and absolute alcohol as starting materials.Li4Ti5O12-polyaniline(Li4Ti5O12-PAn)composite was prepared by in situ polymerization method using aniline, ammonium persulfate and hydrochloricarried as starting materials.Li4Ti5O12-PAn composite was characterized by X-ray diffractometry(XRD),infrared spectrum(IR)combined with electrochemical tests.The results show that the electrical conductivity is enhanced obviously due to the introduction of PAn to Li4Ti5O12.Li4Ti5O12-PAn composite exhibits better high-rate capability and cyclability than Li4Ti5O12.The composite can deliver a specific capacity of 191.3 and 148.9 mA·h/g,only 0.13%and 0.61%of the capacity is lose after being discharged 80 times at 0.1C and 2.0C,respectively.

Structure and visible photocatalytic activity of nitrogen-doped meso-porous TiO_2 layer on Ti6Al4V substrate by plasma-based ion implantation

The nitrogen-doped porous TiO2 layer on Ti6Al4V substrate was fabricated by plasma-based ion implantation of He, O and N. In order to increase the photodegradation efficiency of TiO2 layer, two methods were used in the process by forming mesopores to increase the specific surface area and by nitrogen doping to increase visible light absorption. Importantly, TiO2 formation, porosity architectures and nitrogen doping can be performed by implantation of He, O and N in one step. After implantation, annealing at 650 ℃ leads to a mixing phase of anatase with a little rutile in the implanted layer. By removing the near surface compact layer using argon ion sputtering, the meso-porous structure was exposed on surfaces. Nitrogen doping enlarges the photo-response region of visible light. Moreover, the nitrogen dose of 8×1015 ion/cm2 induces a stronger visible light absorption. The photodegradation of rhodamine B solution with visible light sources indicates that the mesopores on surfaces and nitrogen doping contribute to an apparent increase of photocatalysis efficiency.