Effect of low-energy proton on the microstructure,martensitic transformation and mechanical properties of irradiated Ni-rich TiNi alloy thin films

Ni–48.5 at%Ti thin films were irradiated in the austenite phase by different energy-level protons at a dose rate of 1.85 × 10~(12)p/(cm~2·s), and the total dose was 2.0 × 10~(16)p/cm~2. The microstructures of the thin films before and after irradiation were evaluated by transmission electron microscopy(TEM) and grazing-incidence X-ray diffraction(GIXRD), which showed that the volume fraction of Ti_3Ni_4 phase elevated with proton energy level. The influence of proton irradiation on the transformation behavior of the Ti Ni thin films was investigated by differential scanning calorimetry(DSC). Compared with the unirradiation film, the reverse transformation start temperatures(As) decreased by about 3°C after 120 ke V proton-irradiation. The proton irradiation also had a significant effect on the mechanical properties of the Ti Ni thin films. After 120 ke V energy proton-irradiation, the fracture strength increased by 8.44%, and the critical stress increased by 21.1%. In addition,the nanoindenter measurement image showed that the hardness of the thin films increased with the increase of proton-irradiation energy. This may be due to the defects caused by irradiation, which strengthen the matrix.     

Preparation of CuInSe2 thin films by four-step process

A simple process for the deposition of CulnSe₂ thin films was described. The CulnSe₂ compound was prepared by selenization of Cu-In alloy precursors, which were electrodeposited at a constant current. The selenized precursors were compacted and then annealed. The films were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results indicate that single-phase CulnSe₂ is formed at 250℃ and its crystallinity of this phase is improved as the annealing temperature rises. The losses of In occur in selenization process. The dense CulnSe₂ film with comparatively smooth surface can be obtained by compaction under the pressure of 200 MPa.     

Study of phase separation in Ga25Se75 xTex chalcogenide thin films

The effects of composition and thermal annealing in between glass transition and crystallization temperature on the optical and structural properties of Ga25Se75-xTex were investigated. The glass transition and crystallization temperature of the synthesized samples was measured by non-isothermal DSC measurements. Amorphous thin films of Ga25Se75-xTex glasses were grown onto ultra clean glass/Si wafer (100) substrates using the vacuum evaporation technique. The effect of thermal annealing on the optical gap (Eg) for Ga25Se75-xTex thin films in the temperature range 358-388K is studied. As-prepared and annealed thin films were characterized by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and optical absorption. Thermal annealing was found to be accompanied by structural effects, which in turn, lead to changes in the optical constants. The optical absorption coefficient (a) for as-deposited and thermally annealed films was calculated from the absorbance data. From the knowledge of absorption coefficient at different wavelengths, the optical band gap (Eg) was calculated for all compositions of Ga25Se75-xTex thin films before and after thermal annealing. Results indicate that allowed indirect optical transition is predominated in as-deposited and thermally annealed thin films. The influence of Te incorporation and thermal annealing in Ga25Se75-xTex thin films results in a gradual decrease in the indirect optical gap, this behaviorcan be explained as increased tailing. The decrease in optical band gap and an increase in absorption coefficient and extinction coefficient with thermal annealing can be attributed to transformation from amorphous to crystalline phase.     

Influence of annealing temperature on structure and photocatalytic activity of TiO2 thin films prepared by DC reactive magnetron sputtering method

Transparent TiO₂ thin films were successfully prepared on high purity silica substrates by DC reactive magnetron sputtering method and annealed at different temperatures. The effects of the annealing temperature （300-600 ℃） on crystalline structure, morphology, and photocatalytic activity of the TiO₂ thin films were discussed. The photocatalytic activity of the films was evaluated by photodegradation of methylene blue solution. With increasing annealing temperature, the photocatalytic activity of the TiO₂ thin films gradually increased because of the improvement of crystallization of anatase TiO₂ thin films. At 500 ℃, the TiO₂ thin film shows the highest photocatalytic activity due to the improvement of crystallization of anatase TiO₂ thin films. When the annealing temperature increases to 600 ℃, the photocatalytic activity of thin film decreases owing to the formation of rutile phase and the decrease of surface area.     

Molecular dynamics simulations of non-Fourier heat conduction

Unsteady heat conduction is known to deviate significantly from Fourier＇s law when the system time and length scales are within certain temporal and spatial windows of relaxation. Classical molecular dynamics simulations were used to investigate unsteady heat conduction in argon thin films with a sudden temperature increase or heat flux at one surface to study the non-Fourier heat conduction effects in argon thin films. The studies were conducted with both pure argon films and films with vacancy defects. The temperature profiles in the argon films showed the existence of mechanical waves when the thin film was suddenly heated and the wave nature of the heat propagation. The flux phase relaxation time, Zq, and the temperature phase relaxation time,τt, were calculated from the temporal variations of the energy flux and temperature distribution in the film. Comparisons of the MD temperature profiles with temperature profiles predicted by Fourier＇s law show that Fourier＇s law is not able to predict the temperature variations with time. Different film thicknesses were also studied to illustrate the variation of the time needed for the films to reach steady-state temperature profiles after a sudden temperature rise at one surface and to illustrate the finite speed of the energy waves.     

工艺参数对激光熔覆FeNiCoCrTi0.5高熵合金涂层组织和性能的影响

FeNiCoCrTi_0.5 coatings with different process parameters were fabricated by laser cladding. The macro-morphology, phase, microstructure, hardness, and wear resistance of each coating were studied. The smoothness and dilution rate of the FeNiCoCrTi_0.5 coating generally increased with the increase of specific energy (E_s), which is the laser irradiation energy received by a unit area. FeNiCoCrTi_0.5 coatings at different parameters had bcc, fcc, and Ti-rich phases as well as equiaxed, dendritic, and columnar structures. When E_s increased, the size of each structure increased and the distribution area of the columnar and dendritic structures changed. The prepared FeNiCoCrTi_0.5 coating with the E_s of 72.22 J·mm–2 had the highest hardness and the best wear resistance, the highest hardness of the coating reached HV 498.37, which is twice the substrate hardness. The average hardness of the FeNiCoCrTi_0.5 coating with the E_s of 72.22 J·mm–2 was 15.8% higher than the lowest average hardness of the coating with the E_s of 108.33 J·mm–2. The worn surface morphologies indicate that the FeNiCoCrTi_0.5 coatings exhibited abrasive wear.     

Impact of high dose Kr+ ion irradiation on the corrosion behavior and microstructure of Zircaloy-4

In order to investigate the ion irradiation effect on the corrosion behavior and microstructure of Zircaloy-4, the Zircaloy-4 film were prepared by electron beam deposition on the Zircaloy-4 specimen surface and irradiated by Kr ions using an accelerator at an energy of 300 keV with the dose from 1×1015 to 3×1016 ions/cm2. The post-irradiation corrosion tests were conducted to rank the corrosion resistance of the resulting specimens by potentiodynamic polarization curve measurements in a 0.5 mol/L H₂SO₄ water solution at room temperature. Transmission electron microscopy (TEM) was employed to examine the microstructural change in the surface. The potentiodynamic tests show that with the irradiation dose increasing, the passive current density, closely related to the surface corrosion resistance, decreases firstly and increases subsequently. The mechanism of the corrosion behavior transformation is due to the amorphous phase formation firstly and the amorphous phase destruction and the polycrystalline structure formation in the irradiated surface subsequently.     

Effect of Irradiation Crosslinking on Polyethylene Terephthalate Flame-Retardant Fabric

Irradiation cross-linking of flame-retardant polyethylene terephthalate( FR-PET) fabric with the presence of trimethylolpropane triacrylate( TMPTA) was studied. Thermal gravimetric( TG) analysis,differential scanning calorimetry( DSC) and scanning electron microscopy( SEM) were used to analyze the effects of irradiation crosslinking on structure and property of FR-PET fabric with TMPTA. The cross-linking was promoted by the introduced sensitizer. The gel content was 5.94% at the lower dose of 90 kGy and it arrived at the highest level of 13.01% with the increased doses. There were no melt drips of FR-PET fabric after irradiation cross-linking while the flame retardance disappeared at the time of combustion. The melting temperature of irradiated fabric decreased and TG analysis showed that the onset temperature of degradation of FR-PET fabric and the amount of nonvolatile residue at 800℃ increased as the irradiation dosage increased,but it changed a little compared with the pure FR-PFT fabric. SEM photographs showed that the residue char of irradiated PET fabrics after vertical test remained the intrinsic crossed structure,and the enlarged graph showed that the char was uniformly distributed and it was tight honeycombs structure.     

Tailoring of microstructure and martensitic transformation of nanocrystalline Ti–Ni-Hf shape memory thin film

The amorphous Ti-Ni-Hf thin films with the specific compositions were prepared from single Ti-Ni-Hf alloy target by adjusting processing parameters of direct current magnetron sputtering deposition. Prior to the crystallization,a glass transition occurred in the present Ti-Ni-Hf thin films. The annealed Ti-Ni-Hf thin films were characterized by the nano-crystalline. With the annealing temperature increasing, the grain size firstly increased and then decreased owing to the presence of(Ti,Hf)_2Ni precipitate. Two endothermic and exothermic peaks corresponding to B19'■B2 martensitic transformation in heating and cooling curves were observed for the Ti-Ni-Hf thin films with the lower annealing temperature and shorter annealing time, which was closely related to the inhomogeneous composition. However, the Ti-Ni-Hf thin films annealed at higher annealing temperature and longer annealing time showed the single stage B19'■B2 martensitic transformation. In addition, the martensitic transformation temperatures firstly increased and then decreased with the annealing temperatures rising.     

Behavior of NiCrAlY coating on the TC6 titanium alloy

A NiCrAlY coating was deposited on the TC6 titanium substrate by arc ion plating (ALP). The structure and morphologies of the NiCrAlY coating were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the influence of vacuum heat treatment on the element diffusion behavior was studied. The results showed that the γ'-Ni₃Al phase was precipitated on the NiCrAlY coating after heat treatment. The Ni₃(AI,Ti), TiNi, and Ti₂Ni intermetallic layers appeared at the interface from the outside to the inside at 700℃, and the thickness of the intermetallic layers increased with the increase in temperature. At 700℃ Ti and Ni were the major diffusion elements, and the diffusion of Cr was observed when the heat treatment temperature increased up to 870℃. The violent inward diffusion of Ni at 950℃ resulted in the degradation of the NiCrAlY coating.     

CaCO<Subscript>3</Subscript> film synthesis from ladle furnace slag: morphological change,new material properties,and Ca extraction efficiency

A rapidly air-cooled ladle furnace slag (RA-LFS), which is a type of steelmaking slag discharged from a steel mill, was used to synthesize CaCO₃ film. The CaCO₃ film with 35 cm2 of surface area was synthesized under atmospheric conditions, and the surface morphology of the CaCO₃ films was changed by using additives (CaCl₂ and ethylene glycol). Especially, the addition of CaCl₂ changed the surface morphology of CaCO₃ film with pore and induced new material properties, such as water adsorption. The (012) face of CaCO₃ film (calcite) was rapidly decreased by the addition of CaCl₂. The major components of RA-LFS were calcium (type of CaO, 53.9wt%) and aluminum (type of Al₂O₃, 37.9wt%), and the major crystal phases of RA-LFS were C₃S, C₁₂A₇, and C₃A. The calcium extraction efficiency of RA-LFS was significantly increased after the CaCO₃ film synthesis. The material properties (hardness and elastic modulus) and the thermal characteristics of the CaCO₃ films were analyzed by nano-indentation and thermogravimetry-differential thermal analysis. The synthesized CaCO₃ films from RA-LFS and Ca(OH)₂ (reagent) showed similarities in terms of their material properties and the decomposition temperature.     

Structural and optical properties of Zn1−xNixTe thin films prepared by electron beam evaporation technique

Zn1-xNixTe thin films with different composition(x=0.0, 0.05, 0.10, 0.15 and 0.20) were deposited on glass substrate by electron beam evaporation technique followed by its characterization using advanced structural and optical analysis techniques. Structural properties of the prepared thin films were studied by X-ray diffraction(XRD). The XRD patterns revealed that the binary compounds transformed into a ternary compound with cubic structure having preferred orientation along the c-direction with(111) planes. Composition analysis of the films was determined by energy dispersive analysis of X-rays(EDAX) and found to be in agreement with the precursor composition. Optical properties such as extinction coefficient(k) and band gap energy of these films were examined by using a spectroscopic ellipsometer. It was found that the extinction coefficient(k) increased with the addition of Ni content in the alloy. In comparison, the band gap energy was also determined by using transmission spectra and found to be agreed with that of the ellipsometric results. These analyses confirm that the band gap energy decreases with the increase of Ni content in the alloy.     

Effect of oxygen partial pressure and transparent substrates on the structural and optical properties of ZnO thin films and their performance in energy harvesters

Zinc oxide (ZnO) thin films were deposited onto different substrates-tin-doped indium oxide (ITO)/glass, ITO/polyethylene naphthalate (PEN), ITO/polyethylene terephthalate (PET)-by the radio-frequency (RF) magnetron sputtering method. The effect of various O₂/(Ar+O₂) gas flow ratios (0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6) was studied in detail. ZnO layers deposited onto ITO/PEN and ITO/PET substrates exhibited a stronger c-axis preferred orientation along the (0002) direction compared to ZnO deposited onto ITO/glass. The transmittance spectra of ZnO films showed that the maximum transmittances of ZnO films deposited onto ITO/glass, ITO/PEN, and ITO/PET substrates were 89.2%, 65.0%, and 77.8%, respectively. Scanning electron microscopy (SEM) images of the film surfaces indicated that the grain was uniform. The cross-sectional SEM images showed that the ZnO films were columnar structures whose c-axis was perpendicular to the film surface. The test results for a fabricated ZnO thin film based energy harvester showed that its output voltage increased with increasing acceleration of external vibration.     

Field Emission of SiCN Thin Films Bombarded by Ar^＋ Ions

SiCN thin films were synthesized by a radio frequency chemical vapor deposition (RFCVD) system on P-type Si (1 0 0) wafers using C2H4, SiH4 and N2 as raw materials.In order to get rid of the oxygen absorbed on the surface and improve the characteristics of electron field emission, Ax^ ions of low energy were used to bombard the samples. The field emission characteristics of SiCN thin films before and after Ar^ bombardment were studied in the super vacuum environment of 10^-6 Pa. It was showed that the turn-on field (defined as the point where the current-voltage curve shows a sharp increase in the current density) decreased from 38 V/μm before bombardment to 25 V/μm after bombardment. And the maximum emission current density increased from 159. 2 to 267. 4 μA/cm^2. The composition before and after Ar^ bombardment was compared using X-ray photoelec-tron spectroscopy (XPS). Our results illustrated that the field emission characteristics were improved after the bombardment of Ar^ .     

Synthesis and Application of a Novel Perfluorooctylated Citric Acid

A novel perfluorooctylated citric acid was synthesized successfully via allylation of triethyl citrate followed by perfluorooctylation, reduction and hydrolysis. The fabrics treated with this compound showed good oil repellent and moderate water repellent properties; the oil repellent rating and the water repellent score were 6 and 80 respectively. Even after 10 washing cycles, the repellent properties were kept at the same level. The finished fabrics also showed some wrinkle-resistant properties, and the dry wrinkle recovery angle was increased by 53°compared with untreated fabrics. The critical surface energy of the treated fabric surface was 20±1 mN/m. This multifunctional compound also showed good water solubility, which would be beneficial for the environmental protection.     

Preparation of CoP films by ultrasonic electroless deposition at low initial temperature

Electroless deposition technology has been considered as a kind of common ways to obtain cobalt alloy films. However, in order to get cobalt alloy films, high temperature(353 K) is necessary during the electroless deposition process which will increase costs and energy consumption. Ultrasonic was introduced during electroless plating process to obtain cobalt alloy films at lower initial temperature. It was found that the cobalt thin films could be prepared at lower initial temperature(323 K) with the introduction of ultrasonic. Therefore, different powers of ultrasonic were applied during the electroless deposition process to prepare CoP thin films on copper substrates from an alkaline bath in this investigation. The effects of different powers of ultrasonic on deposition rate, surface morphology, anticorrosion performance and magnetic property of films were studied. It was found that the deposition rate increased gradually with the rise in ultrasonic powers due to cavitation phenomenon. All the CoP films presented the typical spherical nodular structures with the impact of ultrasonic. Smaller and regular shaped structures could be observed when the films were deposited with higher power of ultrasonic which contributed directly to enhancement of anticorrosion performance. Saturation magnetization and coercivity of thin films increased gradually with the rise in ultrasonic powers during the electroless deposition process due to the higher amounts of cobalt.& 2014 Chinese Materials Research Society. Production and hosting by Elsevier B.V. All rights reserved.     

Effect of roughness and wettability of silicon wafer in cavitation erosion

Material damage of silicon wafer with different roughness and wettability was investigated by using the self-made vibration cavitation apparatus in de-ionized water. Various roughness and wettability of silicon wafer were achieved by changing their morphology and depositing Au, diamond-like carbon films （DLC films） on them. Surface morphology was observed with a scanning electron microscope （SEM） and a surface profilometer, and wettability was characterized by the contact angle measurement. The cavitation erosion results showed that many tiny pits and cracks appeared on the wafer surface as a result of brittle fractures; the number and size of the pits and cracks increased with experiment time, which made material flake away finally; cavitation occurred more easily on the silicon wafer surface with the augment of roughness or contact angle by changing surface morphology or depositing Au, DLC thin film on it, which consequently aggravated cavitation damage.     

Effects of substrate temperature and ambient oxygen pressure on growth of Ba(Fe1/2Nb1/2)O3 thin films by pulsed laser deposition

Ba(Fe1/2Nb1/2)O3 thin films were grown on Pt/TiO2/SiO2/Si substrates with pulsed laser deposition (PLD) at temperatures ranging from 823 to 923 K with the varied ambient oxygen pressure. X-ray diffraction (XRD) data confirmed the single phase of polycrystalline Ba(Fe1/2Nb1/2)O3 thin films. The effects of substrate temperature and ambient oxygen pressure on the surface morphologies of the thin films were investigated by atomic force microscopy (AFM) and the growth dynamics of thin films was discussed. Larger grains and denser surface morphologies were observed with increasing substrate temperature. While finer grains were produced with increasing ambient oxygen pressure due to more frequent collisions between the ejected species and ambient oxygen molecules. The influence of the substrate temperature and ambient oxygen pressure on the dielectric properties was also discussed. Improved dielectric constant and decreased dielectric loss was observed for the thin film deposited at evaluated temperature.     

Microstructure and electric characteristics of AETiO_3(AE=Mg,Ca, Sr)doped CaCu_3Ti_4O_(12) thin films prepared by the sol–gel method

This paper focuses on the effects of alkline-earth metal titante AETiO_3(AE = Mg,Ca,Sr) doping on the microstructure and electric characteristics of CaCu_3Ti_4O_(12) thin films prepared by the sol-gel method.The results showed that the grain size of CCTO thin films could be increased by MgTiO_3 doping.The movement of the grain boundaries was impeded by the second phases of CaTiO_3 and SrTiO_3 concentrating at grain boundaries in CaTiO_3 and SrTiO_3 doped CCTO thin films.Rapid ascent of dielectric constant could be observed in 0.1Mg TiO_3 doped CCTO thin films,which was almost as three times high as pure CCTO thin film and the descent of the dielectric loss at low frequency could also be observed.In addition,the nonlinear coefficient(α),threshold voltage(V_T) and leakage current(I_L) of AETiO_3 doped CCTO thin films(AE = Mg,Ca,Sr) showed different variation with the increasing content of the MgTiO_3,CaTiO_3 and SrTiO_3.     

电化学功能化石墨烯作为铜基复合薄膜的防腐增强材料

Cu–graphene (Gr) composite thin films were prepared by electrodeposition route using in-house synthesized Gr sheets. The Gr sheets were synthesized by the electrochemical exfoliation route using 1 M HClO₄ acid as electrolyte. The Gr sheets were confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The (002) plane of Gr sheets was observed at 2θ of 25.66°. The (002) plane confirmed the crystal structure of carbon peaks. The stretching vibration of C=C bond at a wavelength of 1577 cm?1 and other functional groups of carboxyl and epoxide groups were observed from FTIR. TEM confirmed the transparent structure of Gr sheets. The prepared Gr sheets were used as reinforcement at concentrations of 0.1 and 0.3 g/L with a copper matrix to synthesize the Cu–Gr composite. The prepared composite thin films were characterized by XRD, SEM, and energy-dispersion spectrometry (EDS) for morphological and analytical studies. The presence of Gr sheets in Cu–Gr composite was confirmed by EDS analysis. The prepared Cu–Gr nanocomposite thin film showed higher corrosion resistance compared with pure copper thin films in 3.5wt% NaCl, as confirmed by Tafel plots. Electrochemical impedance spectroscopy complimented the above results and showed that 0.3 g/L composite film achieved the highest film resistance.