Applied Mechanics and Materials Vols. 184-185

Abstract: Plasma arc was used as a heat source to make a surface quenching on alloy cast iron, and orthogonal test was used to optimize the surface hardening technological parameter of plasma arc. The influence of the technological parameters on hardness and depth of the hardening layer was analyzed, and the microhardness and the microscopic structure condition after being disposed were also analyzed and discussed.

Abstract: The both experiments of DSC-TG of vanadic titanomagnetite bearing coal and reduction of the VTMCM pellet in electric furnace were carried out in order to understand the reduction behavior of vanadic titanomagnetite. The results are found that the absorbing heat is very high and reduction products have not only simple phase but also complex solid solutions in the reduction process of vanadic titanomagnetite. It shows that the process is very complex, simple iron oxide and complex iron ones are reduced step-by-step in parallel, the reduction sequence of simple iron oxides and complex ones are Fe₂O₃, Fe₃O₄, FeO and Fe₂TiO₅, FeTiO₃, Fe₂TiO₄, FeTi₂O₅, respectively and the required temperature in which iron oxides can well be reduced should be higher than 1300°C.

Abstract: Utilize the high-energy ball milling techniques (HEBMT) to get a certain thickness of the nanocrystalline layer in gradient structure on TiAl-based alloys surface, while using X-ray diffraction and electron microscopy techniques to analyze the microscopic structure of the surface and study its variation along the depth direction. The results show that through HEBMT, the sample surface can get nanocrystallization and its nano-grain size can be refined to less than 10nm while having a 15μm nanocrystalline layer. Nanoindentation tests show that the surface hardness of the samples after HEBMT can be significantly increased from 340HV to 922HV.

Abstract: The important factors that affect the formability of the cold forging steel are its surface quality and internal defects. The cracking phenomenon was taken place during cold forging of ML25Mn steel. In this study, microstructural analyses were made on around the cracked regions of the steel. The reason of cracking, which occurred during cold forging for ML25Mn steel, was investigated based on SEM observation in detail. The results have shown that the crack forming during cold forging process is not related to the chemical composition for ML25Mn steel. Cracking is not resulted from high hardness of the steel rods. There are some non-metallic inclusions in the matrix of ML25Mn steel, and the film-like inclusions are composed of MnS, CaS and complex oxides containing Mg, Al, Mn, Fe, S, Ca and O. The formation of non-metallic inclusions is the result of the deoxidation and the solidification during smelting and casting of steel.

Abstract: The rolling process of the three-roll cross wedge rolling with non-uniform temperature field was simulated with the finite element method (FEM). The distribution of the temperature and equivalent strain in radial section of rolled pieces was analyzed. The microstructures and properties of different positions in radial section were investigated. The results indicate that the temperature field and equivalent strain are ring-likely distributing in the radial section of rolled pieces. There are high temperature and small strain in the center. The temperature decreases and the strain increase gradually from the center to surface. The microstructures and properties of rolled pieces are different in different positions. The microstructure in the center consists of pearlite and proeutectoid ferrite, while the surface consists of cementite particles and fine ferrite.

Abstract: This paper analyzes the oleophobic characteristics of fluorined polyethylenic microspheres, by the way of gaining weight change experiments in 75# aviation gasoline under the conditions of 50, 70 and 90°C temperature, and indicates that the fluorined polyethylene microspheres have better oleophobic characteristics, and finally it is also pointed out the realistic significance about the application of surface-fluorinated treatment technology in soft overlay roof oil-tank.

Abstract: In order to improve the surface quality of titanium alloy in electric discharge machining (EDM) milling, presents electrode ultrasonic vibration assisted EDM milling in the kerosene fluid which fills with 12g/L SiC abrasive particles. By the comparison test of surface roughness between EDM milling and abrasive particle ultrasonic vibration assisted EDM milling in short pulse(pulse width less than 1μs), it is found that ultrasonic vibration role of SiC particle could effectively improve surface roughness from Ra 0.5μm to 0.2μm. The recast layer and surface crack are analyzed by scanning electron microscope (SEM).Results show the thickness of recast layer reduced 20-30μm and surface crack decreased obviously under the role of abrasive particle ultrasonic vibration. It shows that the combined action of ultrasonic vibration and abrasive particle can dramatically improve the surface quality of titanium alloy in EDM milling.

Abstract: The poly(ethylene terephthalate)(PET) fabric was modified by ultraviolet radiation, nano TiO₂ and H₂O 2 . The results showed that PET fabric could be modified to super wettable fabric, the contact angle of PET fabric irradiated by ultraviolet radiation for 50 min could decrease to 0o in 3.29 second. The Scanning electrical micrograph(SEM) showed there were lots of oxidized products on the surface of modified PET fibers. FT-IR spectra showed modified PET fiber had –COOH, and probably had –NO₂. The X-ray diffraction showed the crystallinity increased greatly, and had two new diffraction peaks.

Abstract: A kind of ordered meso-sized hollow silica spherical material was prepared by hydrothermal route using monodispersed cross-linked polymethyl polymer spheres as template, metacrylate tetraethyl orthosilicate as a silica source. The calcination was empolyed for the removing of template and generation silica hollow spherical materials with meso-sized pores. The adsorption performance of the obtained hollow silica spheres was investigated and the results indicated that the obtained hollow silica spheres had high adsorption capacity for sulfadimethoxine. They were sucessfully used as the dispersive adsorbent for matrix solid phase dispersive extraction sulfadimethoxine from chicken tissue with satisfactory results.

Abstract: Shape-controllable polyaniline (PANI) nanostructures varying from fibers to hairy-PANI were synthesized via chemical oxidation polymerization with perchloric acid as dopant. It has been achieved just by adding extra aniline in the later phase of the same reaction or by adjusting reactive temperature. The diameters of the hairy-PANI fibers can be controlled to 300nm. Scanning electron microscopy was applied to investigate various kinds of morphologies. The mechanism of forming hairy-fiber morphologies was proposed to the mole ratio of aniline to APS in the later polymerization phase. X-ray diffraction pattern suggested that PANI were an amorphous character. Conductivity of polyaniline synthesized at room temperature was only 10-1 S cm−1 level. The specific surfacearea of the hairy- fibers PANI is more than that of fibers PANI.