Materials Science Forum Vols. 675-677

Abstract: In this paper, curing process monitoring of vacuum infusion molding process (VIMP) based on FBG for glass fiber reinforced vinyl resins was studied. In the experiment, three kinds of sensors were embedded in the composites. Excursion of the wavelength and temperature was tested in the whole curing process. Reflected power was tested by spectrometer in the molding process, the gel point was tested. In addition, 3-point bending test of composites which FBG was embedded in was done. Results showed that FBG could be exactly reflecting the relationship of stress and strain in bending state of composites.

Abstract: Carbon fiber (~5mm long)-reinforced mortar is found to be an effective thermal sensor. In this paper, relations between temperature change and resistivity of carbon fiber- reinforced mortar (CFRM for short) with different carbon fiber contents (0.4%~1.2% by mass of cement) are studied. The results show that during the initial period, the resistivity decreases when the temperature increases (Negative Temperature Coefficient effect). After the temperature reaches a certain value, the resistivity increases when the temperature increases (Positive Temperature Coefficient effect). Besides, with the change of carbon fiber content, the transit temperature of NTC/ PTC effect also changes. Based on the experimental results, the CFRM shows a potential use as a thermal sensor. The mechanisms of temperature- sensitive properties and NTC/ PTC transition are also discussed.

Abstract: Flexible fabric keyboard is a field of smart textile. It can overcome traditional horniness keyboard can’t be foldable and washing. In this laboratory study there is Three Layers Weaved Once structure designed which consists of three kinds of orifice dimension, for example 4 wefts, 8 wefts and 12 wefts. At the same time three kinds of conductive filaments number combined are planed for each orifice dimension. There are 1, 4 and 8 roots of filaments combined together so that contact areas of the conductive material are changed. Then the immediate regain, connection pressure and connection ratio are tested and analyzed for every kind of fabric keyboard switch. It is concluded that 4 wefts orifice dimension and 4 roots of filaments combined is a better project. These findings may assist in recommendations regarding the further development of flexible fabric keyboard. The fabric keyboard switch forms the foundation for many smart textile applications.

Abstract: Basin rubber bearings are frequently used in high-speed railway bridge or passenger special line railway bridge, lead rubber bearings (LRB) are infrequently used in those railway bridges nowdays, the study on earthquake-resistant capability of railway bridge fabricated isolation bearing - the intelligent and functional structure - would be beneficial in engineering practices. Elasto-plastic earthquake responses of high-speed railway bridges fabricated LRB are studied by means of the finite element program, earthquake responses of railway bridges under high-speed vehicles and different earthquake action fabricated and unfabricated isolation bearing are calculated respectively. The results show that: plastic hinge will develop at the bottom of piers in regard to railway bridges with mid-high and low pier; LRB can reduce displacement and inner forces of structures and improve earthquake-resistant capability of structures effectively.

Abstract: Magnetostrictive composites were usually fabricated using a wet process. The settlement of particles in liquid polymers due to the gravity results in the inhomogeneous and low magnetostrictive properties. To solve the problem, magnetostrictive composites were prepared using a dry process, and their properties were tested in this paper. Measurement of magnetostriction on different positions along the length direction of the material indicates the magnetostrictive composites prepared by the dry process present uniform properties due to the uniform distribution of the active particles in the polymer matrix. The saturation magnetostriction and the maximum dynamic magnetostriction of the [1-3] Terfenol-D composites prepared in the study was 1005ppm and 4.08nm/A, respectively, which was larger than the [0-3] ones.

Abstract: A novel cheap blended precursor phenolic resin/poly(vinyl alcohol) (PR/PVA) was developed to prepare carbon membranes. The effect of two curing methods (i.e., crosslinker and preoxidation) on the gas separation performance of their derived carbon membranes was investigated. Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy were used to analyze the thermal stability of precursor and the changes in functional groups on membrane surface. The gas permeation of carbon membranes was tested for H2 and N2. The results show that PR, PR/PVA, and two PR/PVA cured samples have three thermal degradation stages. The thermal stability for original PR/PVA membrane is significantly improved via the method of preoxidation or crosslinker. Similar crosslinking structure is formed by the two curing methods. However, carbon membranes from crosslinker method present two-fold higher in hydrogen permeability and four-fold higher in selectivity than that from preoxidation method.

Abstract: Polymers are often applied in concrete for multiple purposes and aims. For instance, surface impregnation of concrete with silanes is a reliable technology to protect cement-based materials from ingress of aggressive solutions into the materials. An alternative method is to add silane emulsion into fresh concrete or mortar to produce integral water repellent materials. In this contribution integral water repellent concrete was prepared by adding 1 %, 2 %, 3 %, 4 % and 6 % of silane emulsion. The influence of silane emulsion on the compressive strength, porosity and pore size distribution, water capillary suction and chloride penetration have been investigated. The results indicate that addition of silane emulsion moderately reduced compressive strength of concrete. With 3 % of silane emulsion the reduction is about 10 %. The addition of silane emulsion hardly has influence on pore size distribution. Silane does not block the capillary pores, but only forms a hydrophobic film on the walls of capillary pores. Addition of silane emulsion reduces water capillary suction significantly. The reduction rate is higher than 89 %. Even the surface of integral water repellent concrete is abraded off 7 mm, the material still demonstrates high water repellency because the entire volume is hydrophobic. In addition, chloride penetration also can be reduced substantially.

Abstract: The effect of negative pulse voltage on the microstructure and corrosion resistance of microarc oxidation film of A356 aluminum alloy treated by microarc technique was investigated by SEM, coating thickness gauge and electrochemical workstation etc. The results show the negative pulse voltage greatly influences the microstructure and corrosion resistance of microarc oxidation film by its electrode reaction. The film thickness increases while the size of pore and roughness of the film surface decreases initially and then increases with negative pulse voltage increasing. The microarc oxidation treatment considerably improved corrosion resistance, and the highest corrosion potential was -1.16V, which was 0.38V higher than that of substrate, and the corrosion current was lower than that of substrate about three orders of magnitude.

Abstract: The organic-inorganic hybrid sol was prepared using an alkaline silica sol modified by acid-catalyzed hydrolytic polycondensation of methyltrimethoxysilane (MTMS) in a water-bath condition of 60oC, and then the water-based primer and topcoat were prepared through adding the pigments and nano-TiO2 suspension respectively. Through spraying and baking, the organicinorganic composite coating on the treated aluminum alloy was obtained. The optimum range of P/B (weight ratio of the pigment/binder) is determined between 1:1 and 1.5:1 by investigating the influence of the P/B of the primer on the adhesion and impact resistance of the coating. The microstructure of the coating was characterized by optical microscopy and scanning electron microscopy. The results show that there are lots of holes and lamellar structure in the primer coating and the obtained topcoat coating is uniform, smooth and dense. The coating of ~30 μm in thickness is mainly composed of three elements of silicon, aluminum and titanium, in which transition layer of ~10 μm is included. The physicochemical properties suggest that the coatings on aluminum alloy can meet the needs of finishing coating very well.

Abstract: Zirconia (ZrO2) films were deposited by metal-organic chemical vapor deposition (MOCVD) on {1 0 0} Si single crystal using Zr(thd)4 precursors. The thickness of obtained films is typically of 3.5 μm. The samples have been characterized by Field-Emission-Gun Scanning Electron Microscopy (FEG-SEM) for morphologic and microstructure study, and by X-ray Diffraction (XRD) for crystalline structure. The microstructure analysis showed that unexpected stable single tetragonal phase preferentially grew in low temperature area. According to the literature, the tetragonal phase stabilization is related to the crystalline size and the internal compressive stress. To analyze the effect of grain size and internal stress on the phase transformation, the thermal annealing were carried out in different temperatures and internal stress was measured by XRD method.