Advanced Materials Research Vols. 557-559

Abstract: Pure BiFeO₃ (BFO) and Bi_0.9Nd_0.1Fe_0.925Mn_0.075O₃ (BNFM) thin films were deposited on Pt(111)/Ti/SiO₂/Si substrate by sol-gel method. X-ray diffraction analysis showed that all the films were single perovskite structure and a phase transition appeared in Nd–Mn codoped BiFeO3 thin films. Electrical measurements indicated that the ferroelectric properties of BFO thin films were significantly improved by Nd and Mn codoping. BNFM films exhibit a low leakage current and a good P-E hysteresis loop. The remanent polarization (Pr) value of 74μC/cm² has been obtained in BNFM films, while the coercive field (Ec) is 184kV/cm.

Abstract: Nano-SiC/MCrAlY graded coating was prepared by laser multi-layer cladding on TiAl base intermetallic alloy using composite MCrAlY powders with 1%, 2%, and 3% nano-SiC particles (mass fraction) in turn. The microstructure and microhardness of the composite coating were analyzed by means of scanning electron microscope (SEM) and Vickers microhardness tester. The results show that the microstructure of the composite coating was refined and composed of fine equiaxed grains because of addition of nanometer SiC particles, and the crystal size becomes small with increasing the nano-SiC content in the coating. In addition, due to small size and formation heat of the nano-SiC particles, SiC particles decompose and form new carbides in the coating after laser cladding. The hardness of the composite MCrAlY coating is obviously improved due to enhancement of multi-carbide and refinement of structure.

Abstract: CdS thin films were prepared by chemical-bath deposition (CBD) from a bath containing thiourea, acetic cadmium, ammonia and ammonium acetate in aqueous solution onto glass substrates at 80°C with stirring. The influence of pH value on the surface morphology and optical properties of the CdS thin films was investigated. Step height measurement instrument, scanning electron microscopy (SEM), X-ray diffraction (XRD), spectrophotometer and digital four-point probe resistance measurement were used to characterize their thickness, surface morphology, crystal structure, electrical and optical properties. Uniform CdS thin films were obtained when pH=11.6. There are obvious diffraction peaks at 26.04° when pH is 11.6. The transmittance increases as the pH values increase. The experiment show that pH value play a vital role in the properties of the CdS thin films.

Abstract: Aluminum oxide-doped zinc oxide (AZO) films were deposited by radio frequency (RF) magnetron sputtering at various substrate temperatures and sputtering powers with pure argon flow. Their electrical and optical properties and microstructures were investigated by X-ray diffractometer (XRD), atomic force microscope (AFM), ultraviolet-visible spectrophotometer, four-probe tester. The investigation indicates that the electrical and optical properties and microstructures of the AZO films are remarkably influenced by substrate temperature and sputtering power. With the sputtering power increasing from 60W to 180W, the diffraction peaks rise significantly, the resistivity decreases quickly and the visible transmission is all quite high. When the substrate temperature increases from 25°C to 400°C, the diffraction peaks rise first and lower then both quickly, the resistivity decreases first sharply and then very slowly, and the visible transmission is also high. The films deposited at the substrate temperature 300°C with the sputtering power 180W have low resistivity 1.2×10^–3 Ω•cm and high transmittance 92% at the same time.

Abstract: In this study, Ni-Fe₃O₄ composite particles are deposited on polyester fabric modified with 3-aminopropyltrimethoxysilane (APTMS) by electroless plating. Surface morphology, chemical composition and crystal structure of the Ni-Fe₃O₄ deposits were investigated by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD), respectively. The magnetic properties of the Ni-Fe₃O₄ composite plated polyester fabric are also evaluated. Relatively dense plating was obtained under the given plating conditions. As the Ni-Fe₃O₄ weight on the treated fabric is 34.28g/m2, the saturation magnetization of the sample was 2.88emu/g.

Abstract: Electron beam source was applied to investigate the effect of current, voltage and the number of pulse on surface morphology evolution of high speed steel. It has been revealed that the same trend of the morphology can be acquired by varying different parameters because energy is the main influencing factor. Material own defects and electron back-scattering are the primary reason for the formation of the craters as a result of the eruption of phase boundary. Through the following self- and re-melting repairing, the craters become shallow and the holes disappear. And the planar stress wave justified by the multi-loop craters is the root of the appearance of micro-cracks and cavities.

Abstract: Uniform and highly adherent thin films of TiO₂ and Nd-TiO₂ were deposited on high silica fiber by sol-gel dip coating method in this study. The surface morphology and properties of synthesized composites films were characterized by XRD, SEM, TEM and XPS. The photocatalytic reactivity studies of TiO₂ and Nd-TiO₂ films were evaluated by photodegradation of the methyl orange (MO) under ultraviolet irradiation. The results shown that neodymium doped TiO₂ films have higher photodegradation efficiency than that pure TiO₂ films. The photocatalyst on high silica fiber have a higher photocatalytic activity compare to the glass due to it is light-guide fiber.

Abstract: Organic flame retardant of N-P complex type and inorganic flame retardant hydrotalcite were respectively added to waterproof breathable coating agent ,the influence of dosages of two fla- me retardants on the flame retardancy of coated fabric were studied ,and the influence of the optim- al dosages of different flame retardants on the waterproof breathable permeability of coated fabric were investigated . The results show that adding inorganic flame retardant hydrotalcite has better flame-retardant and waterproof breathable permeability when the addition of hydrotalcite is 5% quality of coating agent , after-flame time and after-glow time of coated fabric are 0s, char length is 10.5cm, moisture quantity is 7247g/m²•24h, water pressure resistance is 430mmH2O.

Abstract: The Cr_1-xAl_xN coatings were deposited onto M2 tool steel using ion arc plating technique. The effect of current density on the surface morphology and mechanical properties of TiN/CrAlN coating was made. It was found that adjusting the pure metal target currents is not only to change the metal atomic ratio, but also to influence the surface morphology, their hardness and adhesion. The micro hardness Hv increases almost linearly with Al content of the coating in this study, and the Cr_0.41Al_0.59N coating reaches Hv 2950. The adhesion force between the coating and the substrate reaches maximum value 55N, when the [Al]/[Al+Cr] ratio is 0.44.

Abstract: Ceramic coatings were successfully fabricated on Mg-7Li alloy in Na₂SiO₃ electrolyte by microarc oxidation (MAO). The phase composition, formation mechanism and infrared emissivity of the coatings were investigated. Results show that the surface of MAO coating exists some micropores with a diameter of 2-6μm due to electric breakdown. The MAO coating with 13μm thickness is mainly composed of MgO, Li₂O₂ and Mg₂SiO₄. The infrared emissivity of the MAO coating is higher than that of bare Mg-7Li alloy, mainly because the coating consisting of ionic crystals has lower lattice vibration symmetry and larger dipole moment.