Showing papers by "Xingcheng Xiao published in 2010"

Self-healable graphene polymer composites

Abstract: We report here a simple and scalable process to fabricate graphene shape memory polymer composites. The graphene material was nanolayered graphene synthesized by a microwave plasma enhanced chemical vapor deposition method. The free standing nanolayered graphene, in its pristine state, was used as a filler to fabricate epoxy based shape memory polymer composites by (1) direct dispersion in the diamine curing agent; (2) thermal curing with diepoxides. The shape memory properties of the polymer matrix impart a thermal healing capability into the composites, which was greatly enhanced at ultra-low filler contents of 0.0025 and 0.0125 vol%.

Encoding localized strain history through wrinkle based structural colors.

Abstract: Surface wrinkles are created on a metallic film supported on a shape memory polymer substrate. The wrinkle wavelength approaches that of visible lights, resulting in diffraction colors. The spatial and geometric distribution of the surface wrinkles can be controlled in an arbitrary fashion, allowing the capture of a three dimensional arbitrary image on a macroscopically flat surface.

Viscoelastic behavior and force nature of thermo-reversible epoxy dry adhesives.

Abstract: The gecko adhesion phenomenon has stimulated efforts to produce synthetic patterned dry adhesives. Besides introducing surface patterns on dry adhesives, it is also highly desirable to understand their intrinsic material properties. This communication reports the viscoelastic behavior of non-patterned epoxy elastomers exhibiting intrinsic adhesion that is much higher than that of elastomers typically used for structure patterning. The diverse molecular origin of the adhesion is revealed through the study of adhesion against various substrates.

Tailoring nanocrystalline diamond coated on titanium for osteoblast adhesion.

Abstract: Diamond coatings with superior chemical stability, antiwear, and cytocompatibility properties have been considered for lengthening the lifetime of metallic orthopedic implants for over a decade. In this study, an attempt to tailor the surface properties of diamond films on titanium to promote osteoblast (bone forming cell) adhesion was reported. The surface properties investigated here included the size of diamond surface features, topography, wettability, and surface chemistry, all of which were controlled during microwave plasma enhanced chemical-vapor-deposition (MPCVD) processes using CH4-Ar-H2 gas mixtures. The hardness and elastic modulus of the diamond films were also determined. H2 concentration in the plasma was altered to control the crystallinity, grain size, and topography of the diamond coatings, and specific plasma gases (O2 and NH3) were introduced to change the surface chemistry of the diamond coatings. To understand the impact of the altered surface properties on osteoblast responses, cell adhesion tests were performed on the various diamond-coated titanium. The results revealed that nanocrystalline diamond (grain sizes <100 nm) coated titanium dramatically increased surface hardness, and the introduction of O2 and NH3 during the MPCVD process promoted osteoblast adhesion on diamond and, thus, should be further studied for improving orthopedic applications. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

Stress-induced Sn Nanowires from Si–Sn Nanocomposite Coatings

Abstract: The growth of stress-induced tin (Sn) whiskers has been considered responsible for the failure of many electronic devices and many approaches have been developed to mitigate their growth. In this report, however, we describe a simple approach based on the same mechanism to promote the growth of Sn nanowires. The thermal expansion induced stress was utilized as the driving force to initiate the growth of Sn nanowires from Si–Sn phase-separated nanocomposite coatings. The nanostructure of the Si–Sn matrix was the key to controlling the shape and diameter of Sn nanowires. This approach provides additional flexibility for making desirable metallic nanowires with controlled dimensions.

Assembly for and method of forming localized surface wrinkles

Abstract: An assembly including and method of forming arbitrary localized wrinkles upon a surface utilizing a shape memory polymer substrate and rigid overlay, wherein the geometrical distribution of the wrinkles is produced by recovering a lateral strain history within the substrate and buckling the overlay, and the localized wrinkles are used to create, among other things, optically three-dimensional engaging surfaces, structural colors, modified surface texturing, and haptic alerts

Improved seal performance for hydrogen storage and supply systems

Abstract: The performance and durability of static and dynamic seals for hydrogen storage and supply systems has been improved by utilizing a spring-energized and plastic coated radial seal in combination with at least a mating surface that has been treated by one of a variety of procedures. These procedures include applying to the mating surface a low-friction, hard, and hydrogen impervious coating, chemically polishing the mating surface, and electrochemically polishing the mating surface. Each of these procedures significantly reduces, on a microscopic scale, the surface roughness of the mating surface. The seal can thus form a tighter and more gas-tight seal with the smoother mating surface so as to decrease the loss of hydrogen gas across the seal. The smoother mating surface can also improve seal life by reducing seal surface wear.

Thermally-insulated vibration welding tool

Abstract: A welding assembly for forming a weld along a welding interface of a work piece(s) using vibrations includes a welding tool and a thermal barrier. The thermal barrier is at least a chemical and/or mechanical insulating layer positioned adjacent to the welding tool, which minimizes the rate of dissipation of heat generated by the vibrations at or along the welding interface. The welding assembly may also include a wear-resistant layer adjacent to the thermal barrier, which protects the thermal barrier from damage or wear. The welding tool is a portion an anvil assembly and/or a sonotrode assembly. A method of insulating a welding tool includes applying or connecting a thermal barrier to a surface of the welding tool, and minimizing the rate of dissipation of heat generated by the vibrations at or along the welding interface using the thermal barrier, which includes an insulating layer.

Windshield Wipers and Methods for Producing Windshield Wiper Materials

Abstract: Wiper blade materials and methods for forming the same. The wiper blade materials are graphene-polymer composites that have a low coefficient of friction. In forming the grapheme-polymer composites, a relatively small amount of graphene filler is well-dispersed within the polymer and the graphene filler and the polymer favorably interact with one another.

Selbstheilendes und kratzresistentes Formgedächtnispolymersystem

Abstract: Eine exemplarische Ausfuhrungsform offenbart ein Polymersystem, welches ein Formgedachtnispolymermaterial und ein Graphenmaterial enthalt.

Growing metal nanowires

Abstract: A method is disclosed for growing metal (including semiconductor metal) nanowires from a film deposited on a substrate. In an illustrative embodiment tin and silicon are co-deposited, such as by sputtering, on a silicon substrate at, for example, ambient temperature. The deposited tin and silicon do not mix and the film has a tin phase dispersed in a higher melting, lower coefficient of thermal expansion, silicon phase. Upon heating, the tin expands against the silicon and expels small tin wires from the upper surface of the film. Other metal or metal alloy wires may be formed in a like manner using a matrix material and substrate in film deposition that don't mix with the metal composition and, when heated, force the expanding metal to extrude from the film surface as small diameter wires.

Verbesserte dichtungsleistung für wasserstoffspeicher- undzufuhrsysteme

Abstract: Die Leistung und Haltbarkeit von statischen und dynamischen Dichtungen fur Wasserstoffspeicher- und Zufuhrsysteme wurde durch Nutzen einer federvorgespannten und mit Kunststoff beschichteten Radialdichtung kombiniert mit mindestens einer Gegenflache, die durch eine von verschiedenen Methoden behandelt wurde, verbessert. Diese Methoden umfassen das Aufbringen einer reibungsarmen, harten und wasserstoffundurchlassigen Beschichtung auf die Gegenflache, das chemische Polieren der Gegenflache und das elektrochemische Polieren der Gegenflache. Jede dieser Methoden verringert auf mikroskopischer Ebene die Oberflachenrauheit der Gegenflache signifikant. Die Dichtung kann somit eine engere und gasdichtere Dichtung mit der glatteren Gegenflache bilden, um den Verlust eines Wasserstoffgases uber der Dichtung zu verringern. Die glattere Gegenflache kann durch Verringern des Oberflachenverschleises der Dichtung auch die Lebensdauer der Dichtung verbessern.