Advanced Materials Research Vols. 287-290

Abstract: A simple one-step method was developed to electrodeposit gold thin film from HAuCl₄ solution with cyclic voltammetric mode on indium tin oxide (ITO) coated glass. The color of as-prepared gold film can vary from red to blue due to different particle-particle interaction. The Au thin film comprised of isolated gold nanoparticles (GNPs) were red color, while blue gold thin films were obtained by electrodeposition in high HAuCl₄ concentration and the increasing deposition cycles.

Abstract: The gear honing process is a widely used process for gear finishing after heat-treated. The honing ring is profiled by diamond dressing gear, which have the profile of the workpiece to be machined and bonded a single layer of diamond particles. The paper has inroduced the traditional manufacturing methods of diamond dressing gears, positive electroplating and negative electroplating. Then put forward a new manufacturing method, Electroless nickel coating. Composition and condition of electroless composite plating solution, process steps are given. Several diamond dressing gears are made by this new method. Honing experiment testified that it is an applied method and has many advantages.

Abstract: The effects of process parameters such as laser power, scanning velocity and wire feeding speed on weld joint quality has been discussed through some laser welding experiments using coaxial inside-beam wire feeding process method. The results reveal that: Along with the increase of the laser power, weld width and depth are increasing gradually; Coating surface will appear burning loss and deboss when laser power is too large. The increase of scanning velocity decreases the depth and width of molten bath, and abates laser hole-effect, so the metal plate can not be welded penetration. Larger wire feeding speed can avoid welding seam produce burning loss, but it also can strengthen welding wire reflect the laser, and decline the welding.

Abstract: In this study, the feedstock powder for plasma spray was prepared by spray drying and post-sintering at 1360 °C using raw metal oxides. The high emissivity coating was deposited by air plasma spraying (APS). The microstructure, phase structure, flowability and bulk density of the plasma sprayed powder were characterized. The microstructure, bond strength and infrared emissivity of the high emissivity coating were also analyzed in this paper. The results reveal that the feedstock powder present good flowability of 42.36 (sp50g) with the bulk density of 1.94 gpml and is suitable for plasma spraying. A dense coating with the bond strength of 39.6MPa and the porosity less than 5 percent was prepared successfully. The normal emissivity of the coating in all waveband is 0.88 at 300°C and 0.87 at 600°C.

Abstract: Recently a new method for manufacturing bimetal clad pipes is introduced, which can integrate centrifugal casting with extrusion technology organically. Through experimental study on microstructure and properties of bimetallic clad pipes manufactured by centrifugal casting and extruding, the results indicates that bimetal clad pipes with intact metallurgical interface have good bonding properties. Meanwhile wider interfacial zone will be favorable for reducing deformation stress. However there are still a few technical difficulties about the bimetallic clad pipe. Due to chemical composition and properties difference between backing materials and CRA layer, chemical elements will spread and microstructure will change during the process of production and even mechanical behavior of backing metal pipe and corrosion resistance of CRA layer will decline. To meet application requirements, appropriate heat treatment with bimetal clad pipes seems vita.

Abstract: Compared polyvinyl alcohol with citric acid as complexing agent, nanocrystalline nickel-zinc ferrite thin films were prepared by sol-gel method and dip-coating process under different temperature. The phase composition, morphology, magnetic properties and electromagnetic properties of nanocrystalline nickel-zinc ferrite thin films were studied by X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM), vibrating sample magnetometer (VSM) and vector network analyzer. The results show polyvinyl alcohol is the proper complexing agent for the preparation of nanocrystalline nickel-zinc ferrite thin films, which is stacked with sheet crystals and average diameter of about 20nm. The maximum saturation magnetization, the remanence magnetization and the coercivity of prepared nickel-zinc ferrite thin films are 39.38 emu/g, 11.47emu/g and 182.82 Oe, respectively. Through studying the microwave-absorbing properties of thin films, the maximal absorption quantity is determined at 9.2 GHz.

Abstract: Epitaxial films of magnesium silicide Mg₂Si are prepared by magnetron sputtering system on Si (111) substrates. The crystal structures and the surface morphology of the Mg₂Si films are characterized by X-ray diffraction and Field emission scanning electron microscope. The microstructure of Mg₂Si films is obtained. The results show that the Mg₂Si films have a strong Mg₂Si (220) preferential orientation with sputtering power increases, the Mg₂Si (220) peak intensity increases with increasing sputtering power before 100W and then decreases with increasing sputtering power.

Abstract: The Cu thin films have been deposited on Si(100) substrates by magnetron sputtering at room temperature. The samples were heat treated by conventional thermal annealing in different temperatures: 230°C, 350°C, 450°C and 500°C. The interface reaction and atomic diffusion of the Cu films and Si substrates between as-deposited and as-annealed at different temperatures are investigated by means of Rutherford backscattering spectrometry(RBS) and X-ray diffraction(XRD). Some significant results are obtained on the following aspects: (1) According to RBS, as-deposited Cu/Si(100) samples are not found interdiffusion, and the onset temperature of interdiffusion is 230°C. With the increase of temperature, the interdiffusion becomes more apparent. (2) After annealing at 230°C, the XRD results of the samples showed formation of Cu₃Si(300). As the annealing temperature increases, the other copper-silicide phases are formed. The main copper-silicide phase is Cu₃Si(300) after annealing at 500°C. It means that Cu₃Si is a reliable copper-silicide in a wide range for the Cu/Si(100) interface.

Abstract: Transparent conducting aluminum-doped zinc oxide (AZO) films have been prepared on soda-lime glass substrates by radio frequency magnetron sputtering using a high density ceramic target at different substrate temperatures. The structural, morphology, electrical, and optical properties of the AZO thin films were investigated by X-ray diffraction, scanning electron microscope, Hall measurement, and optical transmission spectroscopy, and which were strongly influenced by substrate temperatures. Films with better texture, higher transmission, lower resistivity and larger carrier concentration were obtained for the samples fabricated at higher substrate temperature. The AZO film with the lowest resistivity of 4.63×10⁻⁴ Ω.cm and an average optical transmission of 92% in the visible range was deposited on the substrate heated at 450 °C. The optical bandgap depends on the deposition condition, and was in the range of 3.35~3.59 eV.

Abstract: In this article,we report the results obtained from a study adopting solution of sodium naphthalene complex to modify the poly(chloro-p-xylylene)(parylene C) thin film.In this work,the function group and the crystal structure of the film before and after modifying are characterized separately with Attenuated Total Reflection Fourier transformation infrared spectroscopy(ATR- FTIR)and X-ray diffraction(XRD).The result of test shows that the bond of carbon(C) and chlorine(Cl) is damaged;The crystalline of the film reduces,and the NaCl crystal exist on the film surface.The surface energy of the film is increased from 28.64mJ/m² to 41.48mJ/m².The generalized analysis result indicated that nucleophilic reagent destructs the C-Cl bond on the benzene ring, the chlorine(Cl) atom on the benzene ring and the sodium ion in modified reagent forms the sodium chloride which adheres to the film surface.