Advanced Materials Research Vols. 538-541

Abstract: The stabilized aluminum titanate (Al2TiO5) film was coated on the silicon carbide (SiC) substrate via nonhydrolytic sol-gel method (NHSG), using anhydrous aluminum chloride and titanium tetrachloride as precursors, ethanol as oxygen donor, different iron sources as stabilizers, and dimethyl mixed dibasic acid (DBE) with the characteristic of environmental protection and high boiling point as solvent. The phase transformation of modified Al2TiO5 xerogel during heat treatment, the effect of different iron stabilizers on the stabilization of Al2TiO5 film, and the influence of the coating process parameters on film-forming quality were investigated by means of DTA/TG, XRD and SEM. The results indicate that ethanol iron as the stabilizer, Al2TiO5 crystal phase can be formed at 750°C. While the temperature is raised further to 1000°C, Al2TiO5 is stable without decomposition, and has better synthesis effect. Selecting iron chloride, iron sulfate and iron ethanol as stabilizers respectively, only iron ethanol is effective to thermal stability of Al2TiO5 film. The best optimal vertical sliding velocity is 3.75 mm/s.

Abstract: W-doped VO₂ thin films were prepared by magnetron sputtering after annealing in vacuum. The structure, morphology, infrared transmittance and phase transition were characterized by X-ray diffractometer, atomic force microscopy(AFM), infrared spectrometer (IR) and differential thermal analysis(DTA), respectively. The results show that after vacuum annealing at 500 °C for 2h, the major phase of W doped films is VO₂. Dopant reduce the phase transition temperature of VO₂ thin films to 21.9°C.

Abstract: Due to their unique physical and chemical properties, vanadium oxide thin films have become a hot research topic. In the present work, Vanadium oxide thin films were prepared by DC reactive magnetron sputtering at different oxygen partial pressure and thermally annealed in Ar atmosphere at 500°C for 2 hours. The microstructure, transmittance, optical band gap, resistivity, and temperature coefficient resistance (TCR) were measured. The results suggest that increasing of oxygen partial pressure can obviously improve the optical and electric properties

Abstract: The world is facing a severe crisis of fresh water shortage. Seawater desalination technology is an ideal answer to this crisis. However, the conventional desalination technologies consume too much energy. New desalination methods are required to reduce the energy consumption. This paper proposes an idea for saltwater desalination based on the ions of contrary sign which attract each other on both sides of a thin insulation film in a high-voltage static electric field. In an insulation pipeline with saltwater, a piece of thin insulation film is installed vertically to the electric field. The positive ions were pumped onto the positive side of the film while the negative ions were pumped onto the negative side of it. Both ions accumulate at both sides of the film at the aid of electric field. The thinner is the insulation film, the stronger of the attractive force between positive and negative ions at opposite sides of the film and the higher the ion concentration on both sides of it. First, a model based on this idea was introduced. Then, four factors were simulated to reveal their effects on the ion distribution characteristics, including the salt concentration, the length of the pipeline, the electric field intensity, and the film thickness. The simulation results show that the desalination idea is practice to eliminate the dissolved ions in salt water and produce fresh water if the insulation film is thin enough and the electric field intensity is strong enough. The electric field only exerts electric force onto not the majority of water molecular but the minority of ions, so this method consumes much less energy than the conventional desalination methods.

Abstract: Lead germanium telluride (Pb1-xGexTe), a pseudo-binary alloy of IV-VI narrow gap semiconductors PbTe and GeTe, is considered a potential mechanically robust high-index coating material. Pb1-xGexTe thin films were evaporated on silicon substrates from the ingots of single crystals using electron beam and resistance heating, respectively. The surface topographies and compositions of thin-films were characterized by using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX); the transmission spectra in a spectral range of 2.5~12 μm were also examined. Thin films demonstrated columnar microstructure; moreover, those evaporated using e-beam heating have much larger granular dimensions, in comparison with those using resistance heating. The measurement of transmittance reveals the advantage of perfect stoichiometry in e-beam evaporated thin films fails to improve optical properties. It can be deduced the scattering from the larger grains may impair the optical transparency. It can be concluded that electron beam evaporation is an optimum deposition choice.

Abstract: In this study, porous polystyrene membranes were prepared by a template-leaching technique. A suspension was first prepared by dispersing both polystyrene and starch in toluene, in which starch was used as leachable component. The weight ratio of starch/polystyrene ranged from 1:1, 1:2 to 1:3, whereas the concentration of the suspensions altered from 1%, 3%, to 5% by weight of polystyrene/toluene. After spin-coating the prepared suspension on the glass substrate, polystyrene/starch thin-film was produced, and then was treated with inorganic acid to remove starch components. The porous films with ordered and homogeneous structures were resulted. Analysis by contact angle measurement, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy analysis (FTIR) show that the microstructures on the porous films were affected by many experimental factors during the formation of thin-film and the following leaching process. Especially the type of the inorganic acid such as HCl, H2SO4, or HNO3, and the concentration of the specific acid selected in the leaching process have dramatic influences on the formation of the porous polystyrene membrane. The results further demonstrated that starch particles can be maximally removed when the films were immersed into the aqueous solution of HNO3.

Abstract: Carbon nitride (CNx) films were fabricated by plasma enhanced chemical vapor deposition technology in methane-ammonia system, in which the plasma was excited by the hollow cathode glow discharge. The composition，microstructure and hardness of the deposited films were investigated by measurements employing X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and nano-indentation experiment. The results indicate that the nitrogen content in the film varies from 4.2 to 8.6 at.% and the nitrogen atoms are bonded to carbon atoms through C-N, C=N and C≡N bonds. Furthmore, higher nitrogen content is in favor of the formation of C-N bond, which may enhance the film hardness.

Abstract: The reed cellulose was extracted from the wild reed in the hot 12% sodium hydroxide (NaOH) aqueous solution. Then, the cellulose membrane was successfully prepared by using the reed cellulose as the raw materials dissolved in the solvent of N-methylmorpholine-N-oxide (NMMO). The characterization of the reed cellulose film was studied by the digital camera, optical microscope and scanning electron microscope (SEM). The results revealed that the reed cellulose membrane is a smooth appearance and good quality film, which could have many applications in the practical filed.

Abstract: Anodic oxide films were prepared firstly on the surface of a 2024 aluminum alloy. Then the effect of different heat-treatment temperatures on the structure and properties of the films was studied. The results indicate that the construction units of Al2O3 oxide film were composed of tubules less than 100nm in external diameter, and the film became more compact and uniform as a result of the increased temperature after the heat treatments of 100, 150, 200, 250, 300, 350, and 400°C under the protection of a H2 atmosphere. The hardness of the films increased linearly with the increase of heat treatment temperature; whereas the wear loss tended to decrease first and then increase. After being treated at the temperature of 250°C, the hardness reaches 606HV, the wear loss is a minimum of 11mg. The structure of the film heat-treated at 250°C has a compact structure, higher hardness, and the best wear resistance.

Abstract: The MoS₂/Sb₂O₃ films were prepared by RF magnetron sputtering. The films were stored in humid environment (25°C, 60%RH) 30 days. The anti-oxidation properties of MoS₂/Sb₂O₃ were studied by XPS. The composition was studied by XRF. The results show that the anti-oxidation properties were improved by doping Sb₂O₃. Introducing Sb₂O₃ into the films provides a substantial benefit to tribology properties of film.