Advanced Materials Research Vols. 335-336

Abstract: Graphene-poly(methyl methacrylate) (GNS-PMMA) composites were prepared by two methods. Graphite oxide nanosheet-poly(methyl methacrylate) (GO-PMMA) composites were prepared of methyl methacrylate monomer and the presence of graphite oxide (GO). Then the GO-PMMA composites were reduced to graphene nanosheet-poly(methyl methacrylate) by using hydrazine hydrate. The obtained composites were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The composite exhibited conductivities in the 1.58×10^-9-4.21 S/cm range, depending on the amounts of graphite oxide and PMMA.

Abstract: There is considerable interest in the use of flexible laminate composite materials to improve the deployable structures for space applications. Critical to acceptance of these materials is the ability to achieve high packaging strains without damage. However, there does exist more or less damage during the process of folding and unfolding for the laminate composites. Better understanding of folding damage, therefore, is needed for the design of laminate composites and folding pattern. In this work we present a study on the fold-resistant characteristics of two different laminate composites, which were fabricated by covering the aramid fiber/epoxy and carbon fiber/epoxy prepregs respectively with polyimide film on both sides. The results of tensile tests on 3-layer structure laminate composites show that the fold-resistant properties of aramid fiber/epoxy composites could be improved with increasing of the resin content and decreasing of the fiber bundle diameter. For carbon fiber/epoxy composites, the effects of resin content and fiber bundle diameter on reduction rate of fracture strength were more complex. There existed a best range of resin content and fiber bundle diameter. The microscopic observations show that folding resulted in piling up of resin and damage of reinforcing fiber, which would decrease the mechanical properties.

Abstract: EPS (expanded polystyrene spheres) templates with thickness of a 10 mm coating on a surface that is mainly consisted of Ni-WC particles, are prepared. Carbon steels containing 0.45C%wt are then cast in the templates using V-EPC process (vacuum expandable pattern casting), forming the surface alloyed steels. The microstructures are observed and analyzed using optical microscope, SEM and EDS. Macrostructural observation showed that the surface alloyed zone is dense and there is no obvious defects, such as gas bubbles, occluded gas holes and delimitation. Microstructural investigations indicate that the samples from top to bottom are obviously consisted of three different zones, i.e., the top alloyed zone, the interim transitional zone and the bottom matrix zone. Ni-WC particles are totally decomposed during the molten steel infiltration. The microstructures in the surface alloyed zone are consisted of small amounts of fine WC+W₂C carbides, large amounts of M₃C+M₇C₃ carbides and dendritic matrix. There is a fine pearlite strip at the top of the transitional layer. Small amounts of carbide particles within the matrix grains and net carbide precipitation in the grain boundaries at the transitional zone can be observed.

Abstract: A new drill pipe steel microalloyed with 0.04 w.t.% Nb was designed to meet the needs of drilling operation in super-deep wells, and the precipitation behavior of Nb during temper was studied in detail. The results show the austenitic grain can be refined by the addition of 0.04 w.t.% Nb, and the steel has a high yield strength of 1192MPa, high tensile strength of 1226MPa and high impact absorbing energy of 137J when the steel is quenched at 900°C and tempered at 550°C, moreover, the volume fraction and dimension of precipitates increases with increasing temper temperature. When the new steel is tempered at 550°C, the new steel has the best comprehensive performance due to the fine dispersed precipitates. The mechanical properties of the new steel are much better than that of the common drill pipe steel.

Abstract: Abstract. This part analyzed clamping automobile tires conveyance’s research situation, summarized its failure problem and occurrence cause, and selected the important failure problem by RPN method; and then solved creatively clamping lever roller’s wear, clamping lever’s excessive damage owing to rise and decrease slightly, the automobile conveyance’s excessive damage owing to the car’s rollover and clamping lever’s bearing load unevenly; in the end, proposed the conceptual design of new-style clamping vertically automobile tires conveyance. The conveyance have a simple structure, decrease the clamping lever’s and car tire’s wear, avoid cantilever phenomenon owing to rise and decrease slightly, decrease the clamping lever’s strength and stiffness.

Abstract: This paper compares the structure and basic points of the new lance with traditional ones, analyses the new design with center hole in head in fields of theoretical supersonic jet characteristics including penetrating depth and stirring energy, operation mode in smelting process and. The application results show its advantages in keeping whole dephosphorizing rate, final carbon-oxygen equilibrium control of steel and cost reducing, on the other hand, point to its several drawbacks. Optimize solutions are introduced at the end.

Abstract: TiC particulates reinforced iron matrix surface composite was produced by cast technique and in-situ synthesis technique. The surface composite was investigated from thermodynamics, microstructure, wear-resistance and oxidation-resistance. The results show TiC particles whose volume fraction is about 40% exhibit fine size in iron matrix on the surface composite. An excellent metallurgy-bond is observed between the surface composite and the gray iron. Fe-TiC surface composite shows good oxidation-resistance at 900°C and great wear-resistance under condition of dry sliding.

Abstract: A new kind of optical fiber corylic resin coating was prepared in this paper. The influence of PVC (pigment volume concentration) to the properties of coatings was studied. The best formula was selected. The best coating was painted on the optical fiber. The relationships of the coating diameter and the distances of the centers of the coating layer and optical fiber were studied. It was found that the circle diameter of coating is greater; the distance of centers of circles is bigger. Finally, the optical fiber with this coating was embedded in resin castings. The cross sections were observed under the same heated situation. The results revealed that the coatings embedded in composites used in large aircraft had no change when it was heated. This kind of coating did not need ultraviolet light or heating, and it’s easy to control the thickness and roundness of the coating by controlling the speed of pulling out the optical fibers. This type coating is a kind of simple heat-resistant coating embedded in composite materials used in the large aircraft.

Abstract: Heterocyclic electron-poor monomer [1,2,5]thiadiazolo[3,4-c]pyridine have been synthesized in high yields over five steps from readily available starting materials. The new deficient acceptor has good solubility in organic solvents so as to permit an appropriate coating process.

Abstract: Abstract: An epoxy based nano-SiO₂/TiO₂/polyimide hybrid enhanced sizing for carbon fiber was prepared by modified SiO₂/TiO₂ precursor in PAA collosol with silane couple agent(WD-50) and eligibility surfactant via sol-gel reaction, and both ultrasonic cavitation and multi-complex technology were used during the process. The properties of PAA-SiO₂-TiO₂ hybrid sizing and micro-morphology of carbon fiber surface were analyzed by FTIR, DSC, Particle Size Analyzer and STM. The results indicated that nanoscale SiO₂•TiO₂ particles dispersed in the hybrid sizing film homogeneously, and a layer with nano particles was formed on carbon fiber surface after treated by the hybrid enhanceing sizing. The roughness was increased and interface properties of carbon fiber would be improved. At the same time both tensile strength and the interlaminar shear strength were increased obviously.