Advanced Materials Research Vols. 105-106

Abstract: Octadecyltrichlorosilane (OTS) was prepared on glass substrate to form self-assembled monolayer (OTS-SAM). The OTS-SAM was then UV-irradiated to endow the film with good chemisorption ability. Zirconia films were formed on silanol SAM by the LPD method. The phase structure and surface configuration of the zirconia films were studied by XRD and SEM respectively. The XRD results indicate that the as-deposited ZrO2 thin films are pure tetragonal phase after being annealed at 500°C for 1 h. SEM images show the zirconia film is uniform, but not very compacted.

Abstract: The high-speed steel (HSS) reinforced by in-situ VC /35CrMo compound roll was produced by electromagnetic semicontinuous casting. The element distribution and the structure morphology of the interface were analysed, and the mechanical properties were tested. The results indicate that the thickness of diffusion layer is around 50μm. The microstructure of the diffusion layer is pearlite, and next to the diffusion layer, the microstructures are ferrite and pearlite at the alloyed steel side. There are in-situ VC particles in martensitic matrix. At the high-speed steel side. The microhardness of HSS and 35CrMo is about 700HV and 250HV, respectively, and that of diffusion layer is near 350HV, which is between that of HSS and 35CrMo. The impact toughness is 100 Jcm-2. On the basis of the experiment, the interface of compound roll prepared by electromagnetic semicontinuous casting obtains good microscopic structure and mechanical properties, which are the results of the metallurgically bonded interface.

Abstract: Nano-TiO2/micro-Cu composite particles were prepared by hydrolysis of Ti(OBu)4 in abundant acidic aqueous solution and subsequent reflux in the presence of micron size Cu powders. The preparation process was optimized using response surface design with the degradation of TiO2/Cu particles to Methyl orange as target. The particle morphology and composition were characterized by FE-SEM, XPS and XRD. The photon absorption properties of composite particles was investigated by the UV-VIS DRS experiments, and the results show the photoabsorption property of composite particles is intermediate between TiO2 particles and Cu powders, showing cooperative effect by the combination of oxide semiconductor particles with metal substrate.

Abstract: The Fe-Based Al2O3-TiC Ceramic Composite was fabricated by combining the methods of Self-propagating High-temperature Synthesis with casting. The microstructures of ceramic layer and interface were characterized via SEM, EDS and X-ray diffraction. The Results show that the microstructure of ceramic layer is dense, and the in-situ Al2O3 and TiC particles with size of 1-2 μm are distributed on the ferrite matrix. The hardness of compact ceramic layer reaches 48HRC, and it has graded distribution from ceramic layer to the ferrite matrix. The composite interface between ceramic and matrix is compact, and takes on flexuous. The composite material bonds in a metallographic manner, with high bonding strength.

Abstract: Using the density functional theory method, we have characterized the geometrical structures and adsorption energy of water clusters adsorption on graphite surface. When one water molecule inter- acts with graphite surface, one of the H-O bonds formed hydrogen-bond with carbon atom in graphite sheet; in the two water molecules structure, the linear dimmer nearly parallel to the graphite surface, and also formed the hydrogen-bond; when the number of water molecules increased to six, all the H-O bond that point to the graphite surface has formed Hydrogen-bond with it. The binding energy of the water clusters with a graphite surface depends only on the number of water molecules that form hydrogen bond.

Abstract: Microarc oxidation (MAO) is a relatively convenient and effective technique to deposit ceramic coatings on the surfaces of Al, Ti, Mg and their alloys. This technique can introduce various desired elements into titania-based coatings and produce various functional coatings with a porous structure. Microarc oxidized (MAO) TiO2-based coatings on titanium alloy were formed in electrolytes containing aluminate and ZrO2 particles. The phase composition of the samples was analyzed by glance-angle X-ray diffraction and the surface morphologies of the samples were observed by a scanning electron microscopy (SEM). In addition, the element concentrations on the surfaces of the samples were measured by an energy dispersive X-ray spectrometer. The experiment results indicated that: MAO coatings, which are porous structures and exhibit good interfacial bonding to the substrate, may possess specific surface structures such as crystal phase, non-equilibrium solid and complex mixed-compounds since complex plasma physical and chemical reactions.

Abstract: The coatings containing zirconia were produced on LY12 Aluminium alloy by micro-arc oxidation in K2ZrF6 and NaH2PO2 solution. The composition, structure, hardness, friction and wear resistance and corrosion resistance of the coating were studied by XRD, SEM, EDS, ball-on-disk friction tester and electrochemical analyzer, respectively. The results show that coating was composed of m-ZrO2 and t-ZrO2. There were a large amount of Zr and O and a little Al, P and K in the coating. The thickness of coating prepared for 3h was 168μm and the maximum value of the hardness was up to 16.75GPa. The friction and wear resistance and corrosion resistance were improved, compared with the LY12 aluminium alloy substrate.

Abstract: Ni-based WC composite coatings conducted on the surface of 45 steels by free spraying followed with high frequency induction remelting were investigated. The influences of induction remelting time on properties of the coating were discussed. The wear resistance of the coating and the elemental diffusion cross the interface between the coatings and the substrate were analyzed. The compositions and microstructure of the coating before and after a wear test were characterized by scanning electron microscope with energy dispersive X-ray microanalysis. The results indicate that a coating which is free from crackers and pores composed of Ni-based solid solution and dispersed tungsten carbide is obtained by free spraying and induction remelting. The interface is a white lamellar zone. The mutual diffusion of iron and nickel in the interface proves it’s an atomic bonding between the substrate and the coating. The wear mechanisms of the coated sample are abrasive wear and microplowing. The wear resistance of Ni-based WC composite coatings is superior to that of quenched high carbon steels.

Abstract: The capability of Rayleigh wave to be used as a tool for the evaluation of CVD DLC coating layer has been presented in this paper. One uncoated specimen and two CVD DLC coated specimen has been used. The dispersion curves of group velocity of leaky Rayleigh wave were measured. The dispersion curve of uncoated specimen shows that the group velocities were same at different frequencies, as there is no coating layer affecting the group velocities at different frequencies. There are distinct different between ‘sound’ specimen and ‘bad bonding’ specimen as the ‘bad bonding’ specimen show unevenness on its dispersion curve.

Abstract: Nanometer TiO2 microcapsule has potential applications in biochemistry, drug Controlled Release, and catalyst. Meanwhile, Ultraviolet (UV) light-induced bioactivity of titanium substrates is attracting more and more attention nowadays. Composite thin films formed by Nano-TiO2 microcapsule prepared by a novel and versatile technique of layer-by-layer (L-b-L) deposition using the Nanometer latex particles of Polystyrene (PS) as the template together with TiO2 films synthesized at low temperature by the hydrolysis of titanium chloride (TiCl4) precursor was successfully deposited on the different titanium substrates after the template was removed. Thus great expectation was placed on whether UV radiation can enhance the bioactivity of the titanium substrates after the composite thin films being deposited on its surface. The apatite-forming ability was evaluated after the UV-irradiated implants being soaked in simulated body fluid (SBF) within different hours by Scanning electron microscopy (SEM), XRD. The vitro results indicated that UV radiation was favored to formation of apatite on titanium substrates. Besides, the effect of different UV- irradiation time on apatite-forming was different.