Advanced Materials Research Vols. 79-82

Abstract: The convex surface of the infrared dome is exposed to the harsh environment of the outside world, and therefore requires a coating which not only increases transmission but is able to withstand rain erosion so as to enhance system performance. This paper deals with the techniques that were developed to deposit a uniform thick SiO2 coating for sapphire dome by radio frequency magnetron sputtering. Results show that average transmission increment in wavelength range from 3 to 5um for the sapphire dome coated on convex surface was more than 4.0%. The transmission non-uniformity over the convex surface of the coated sapphire dome was less than 1.7%.

Abstract: The superhydrophobic and highly oleophobic cotton textile was obtained by applying particle -based in situ fabrication procedure with the low toxic perfluoropolyether (PFPE) and the silica particles. The water contact angle and salad oil contact angle on the treated cotton textile surface can be achieved to 156.8 º and 143.3 º respectively. The microstructure of the treated cotton textile surface was revealed by scanning electron microscopy (SEM). And the chemical composition of the treated cotton textile surface was determined by the X-ray photoelectron spectroscopy (XPS) analysis. Thermogravimetric (TG) analysis showed that the weight loss of the treated cotton is less than that of the untreated sample.

Abstract: We obtained the Eu(TTA)3phen•H2O-PVP composite film by rare earth complexes Eu(TTA)3 phen•H2O was doped intentionally in polyvinylpyrrolidone(PVP), and the factors of effect it’s luminous intensity were investigated. The results indicate that the luminous effect of sample was best when the water and the alcohol proportion is 1: 4 in the resolver, the aggregation-time reached 12 h and the doping concentration of europioun ion reached 0.6%. The infrared spectrum analyses of sample indicate that there is an interaction between Eu(TTA)3phen•H2O and PVP. In addition, the fluorescence spectra and ultraviolet spectrum analyses of sample indicate that polymer materials can not only fix rare earth ions to enhance its luminescence intensity, but also avoid the quenching effect to rare earth caused by water molecule, through the replacement of PVP ligand to water molecule in the complex. The luminous intensity of the rare earth complexes can be greatly enhanced, and the composite film contained high amount of rare earth complexes is obtained, which laid a foundations for further study the film formation properties of rare earth complexes luminous materials.

Abstract: Ni-Cr coating and Ni-Cr/ZrO2 gradated coating were deposited on C45 carbon steel by high velocity arc spraying and micro-plasma spraying to solve the high temperature oxidation problem of medium carbon steel components. The oxidations of Ni-Cr coating, Ni-Cr/ZrO2 gradated coating and C45 carbon steel substrate were carried out for up to 108 hours in air atmosphere at 1100°C. The oxidation behaviors were investigated after detailed examinations by thermal gravimetric analysis (TGA), x-ray diffraction (XRD) and scanning electron microscopy (SEM). Ni-Cr coating and Ni-Cr/ZrO2 gradated coating show similar and low dynamics curve near to the logarithms function. Surface observations with SEM and XRD reveal that the oxidizing surface of the C45 carbon steel substrate is mainly a loose spherical structure consisted of mainly Fe2O3 and Fe3O4. The surface structures of Ni-Cr coating and Ni-Cr/ZrO2 gradated coating after 108 hours oxidization are rather denser than that of C45 carbon steel, which can effectively improve the properties of the oxidation resistance of C45 carbon steel substrate.

Abstract: Titanium alloys are often material of choice for aerospace, chemical and biomedical industries, because of their unusual corrosion resistance, high mechanical strength and low density. However titanium alloys have very poor wear resistance. Hard coatings can be formed on the surface of titanium alloys to improve their tribological property. In this work ion nitriding without hydrogen technique was used to treat Ti-6Al-4V alloy and the nitrided layer was formed on the substrate surface. The fundamental coating properties, such as the phase, component, hardness and elastic modulus were investigated. At the ion-nitriding condition of flux ratio N2/Ar=1:1, pressure 40 pa and substrate temperature 900°C, the nitrided layer was formed. The layer consists of Ti2N and TiN compound. The content of element nitrogen in the nitrided layer gradiently decreases from the the surface to the substrate direction. For a better understanding of the hardness of the nitrided layer, the nano indentation test and microhardness test are both used. The results show that the average values of hardness and elastic modulus for the surface of the nitrided layer are 17.36GPa and 328.81GPa, about 6 times and 3 times respectively as those of Ti-6Al-4V substrate. The hardness of the nitrided layer decreases from the surface to the substrate direction, which corresponding to the content change of element nitrogen. For the result of nano indentation test, when the indentation depth is more than 400nm, the values of hardness and elastic modulus both decrease with the increase of the indentation depth. It is because of the influence of the soft Ti-6Al-4V substrate.

Abstract: As the diamond surface has higher interface energy, the adhesion of surface and matrix is bad, and it makes the diamond shatter easily. For solving this, the microstructures and properties of the metallic coating on the diamond surface which contains W (tungsten) by hydrothermal method are studied. The different temperatures such as 110 ~140°C and 5h insulating were adopted to be coated in high pressure reactor respectively. The metallic coating on the diamond surface was studied by SEM，XRD and so on. The results show that the continuous and compact coating of Ni and W on the diamond surface is formed by the hydrothermal coating technology at 130°C. The heat treatment temperatures were maintained at 850°C for 1h during the heat treatment process. After the corresponding heat treatment, the better layer coatings, of which thickness is about 10μm, are formed for protecting diamonds and reducing the trend of oxidization. The carbide WC (tungsten carbide) at the interface between the coating and diamond surface is formed. The chemical and metallurgical bonding between diamond and coating is obtained. Because of the coating layers formed and the defects on diamond surface made up, the compress strength of diamond after hydrothermal and heat treatment is enhanced. The compressive strength after hydrothermal and heat treatment is higher than that of un-coating particles(those are 29.45% and 83.64% respectively).

Abstract: ZnO thin films have been deposited onto the glass substrates by the sol-gel spin coating method at different chuck rotation rates. The effect of deposition parameters on the structural, optical and electrical properties of the ZnO thin films was investigated. The crystal structure and orientation of the ZnO thin films were investigated by X-ray diffraction (XRD) patterns. The optical absorbance and transmittance measurements were recorded by using a double beam spectrophotometer. The optical absorption studies reveal that the transition is direct band gap energy. The I-V plots of the ZnO thin films were carried out in dark and under UV-illumination. The result shows the obtained ZnO thin films can be used as a photovoltaic material.

Abstract: The biological modification of biomaterials surface was an important means for surface endothelialization. In this work, an extracellular matrix-like (ECM-like) surface modification was developed for inducing endothelialization on titanium cardiovascular implant surface. To solve the problem of antibody denaturing caused in the randomly immobilizing, cluster of differentiation 34 (CD34) antibody was directly immobilized on titanium surface using a layer-by-layer self-assembly (LBL) technique. The biological behaviors of the endothelial progenitor cells (EPCs) on modified titanium surface were investigated by in vitro cell culture experiment. The results showed that the avidin, biotinylated protein A and the CD34 antibody were successfully assembled onto the NaOH etched titanium surface. The results of cells experiment suggested that the CD34 antibody immobilized surfaces promoted EPCs attachment and capture in vitro. It was believed that the response of adhesion, proliferation, differentiation of EPCs to titanium surface was regulated by modifying the surface chemistry which controlled the cell-biomaterial interactions. This work provided a surface biomodification means to increase the biocompatibility of titanium-based vascular implant surfaces.

Abstract: WS2/MoS2/C composite lubricating films were prepared in an Ar/C2H2 atmosphere by magnetron reaction-sputtering using a WS2/MoS2 composite target. The relationship between the microstructure and the tribological performance of the films was investigated. The composite film has a compact microstructure, which is shown to have much superior tribological performance with lower friction coefficient and better wear resistance than pure MoS2 film in humid atmospheric conditions at room temperature. An increase in hardness of nearly one order of magnitude was reached, too.

Abstract: This paper presents the design of ultrasonic vibrator utilizing a piezoelectric actuator. After describing a geometric configuration of the proposed atomizer, an analytical model of the ultrasonic atomizer is formulated by considering liquid film surface theory and wave theory. The dynamic analysis is then undertaken using a finite element analysis to determine principal longitudinal vibration modes. An optimization is performed by taking the amplitude of the tip displacement as an objective function. The fluid flow characteristics of the proposed atomizer is also analyzed under operating conditions through commercial software FLUENT.