Advanced Materials Research Vol. 1096

Abstract: In this study, equilibrium lattice parameters, heat of formation and cohesive energy of four kinds of typical phases with different structure intermetallic compound in Al-Cu-Mg alloy were investigated by first-principles calculations based on density functional theory via CASTEP software. The calculation results are analyzed and show that ternary strengthening phase Al₂CuMg generated first when Mg content is higher, while binary strengthening phase Al₂Cu or Al₃Cu₂ first generated and more stable when Mg content is low in Al-Cu-Mg alloy which indicates that element Cu and Al alloying capacity significantly higher than that of Mg and Al element.

Abstract: Type 303 austenitic stainless steel has been applied in jewelry production, and its nickel release rate has become a concerned issue in the jewelry industry. In this paper, the commercial type 303 stainless steel was used as the test material, while 304 stainless steel as the contrast material; their nickel release rates and corrosion behaviors in artificial sweat were studied. The results show that the actually measured nickel release rate of 303 stainless steel reaches 2.06μg/cm²/week, nearly 25 times higher than that of 304 stainless steel, which exceeds the threshold specified in nickel release standard EN1811:2011 for jewelries coming into direct and prolonged contact with the skin (0.88μg/cm²/week), and its adjusted value also exceeds the threshold specified in Nickel Directive 2004/96/EC for puncture accessories (0.35μg/cm²/week). The high nickel release rate for 303 stainless steel is mainly caused by its high sulfur content and the inevitable formation of manganese sulfide inclusions, which will cause the pitting and exacerbate the material corrosion. Considering the risk of nickel sensitization of 303 stainless steel, it is not suggested to use 303 stainless steel as the jewelry material, especially for piercing jewelry.

Abstract: Stiffness and elastic mechanical properties of the Zr44-Ti11-Cu10-Ni10-Be25 metal glass Alloy have been investigated by nanoindentation and Atomic Force Microscopy.Continuous stiffness measurements were carried out on the as received samples. Max indentation depth of 2000 Nm has been chosen. A 3D analysis of the indent traces has been performed using a Atomic Force Microscope: pile-up at the indentation edge was observed. These metallic glasses, therefore, although showing brittle like linear elastic behaviour up to failure are still capable of undergoing plastic shear flow at the nanoscale level that may potentially lead to high material ultimate properties. Elastic modulus of 116,2 ± 0,9 GPa has been found to be independent on indentation depth while a high hardness of 8,0 ± 0,8 GPa has been measured at low indentation depths (100 nm) that progressively reduces to a constant value of 7,0 ± 0,1 GPa at increasing depths (up to 2000 nm).

Abstract: The rotary experiment apparatus was built to study the erosion-corrosionresistance of carbon steel, 15CrMo steel, duplex stainless steel 2205, nickel based alloy 825 and stainless steel 316L which are commonly used in the sour water environment of refinery. Based on the electrochemical test, the carbon steel and alloys corrosion rates in different ammonium hydrosulfide concentration, fluid velocity and temperature were obtained. The corrosion products film morphology was analyzed by scanning electron microscope (SEM) to find the reasons for corrosion rates difference of carbon steel and alloys. The results showed that the corrosion rates of carbon steel and alloys were increasing with fluid velocity, ammonium hydrosulfide concentration and temperature increase, when the velocity exceeds 6 m/s the corrosion rates essentially unchanged. The maximum corrosion rate of carbon steel at 60 °C and 10 wt% ammonium hydrosulfide concentration was as high as 6.5 mm/year, while the nickel based alloys 825 and stainless steel 316L were less than 1.5 mm/year. The corrosion product films of carbon steel and 15CrMo steel was loose and cracking which can easy to fall off from the substrate when subjected to fluid impact and the corrosive media can easily penetrate into the bottom of corrosion product and continue to corrode substrate. However, the corrosion film of nickel based alloys 825 and stainless steel 316L was dense and tightly bonded to substrate making it has a good corrosion resistance.

Abstract: The sliding friction and wear behaviors of GCr15 steel against GCr15 steel under dry friction and grease lubrication were investigated on a reciprocating friction and wear tester consisting of a ball-on-disc friction pair. The morphologies of the worn surfaces of discs were analyzed by means of scanning electron microscopy (SEM). The result shows that GCr15 steel friction coefficient decreases with the increase of load, and the wear rate decreases with the time going by. There exist larger wear volumes on the friction surface under dry friction, while the wear volumes are relatively minor under grease lubrication. The SEM analysis agree with such results.

Abstract: The use of a silane coupling agent (3-aminopropyltriethoxysilane) to improve the anticorrosive property of low carbon steel was assessed by DC polarization test and infrared spectroscopy. These tests indicated that the optimal hydrolysis system of γ-APS was available at 25 °C, pH 10, and with 7 vol % APS, 28 vol % absolute ethanol and 65 vol % DI water. Factor of silane volume in hydrolysis systems played an important role in the hydrolysis effect of γ-APS.

Abstract: The complex of 2-amino-4-methylthiazole with silver [Ag (C₄H₆N₂S)₂.(CH₃)₂CO] had been synthesized and characterized by elemental analysis, FT-IR and UV-vis spectra. Crystals of the complex were obtained through solvent diffusion method and the structure had been determined by single crystal X-ray diffraction. The nonlinear optical properties were investigated with the density functional theory method. The calculated results show that the complex has high hyperpolarizability of 316.8×10^-30 esu and the metal irons play an important role for the nonlinear optical properties.

Abstract: Poly (o-toluidine) (POT), poly (m-toluidine) (PMT) and poly (p-toluidine) (PPT) were chemically oxidized by ammonium persulfate (APS) as both oxidant and dopant through a very simple self-assembly process. The structure characterizations by elemental analysis, XPS and FTIR demonstrated that APS is served as both oxidant and dopant due to the proton acid produced during polymerization, which is proven by the decreasing pH value of the reaction solution along with the increase of polymerization time. Besides, the influences of the alkyl-substitution position on the molecular structure, polymerization process, morphology and electrical properties are also discussed.

Abstract: Synthesizing barium aluminate using barium carbonate and aluminium hydroxide, the optimum conditions in reaction process of synthesizing barium aluminate were discussed. The phase of the products was characterized by XRD. The results indicate that the optimal synthesizing conditions are established with the yield of 88.43% when the roasting time is 80min, the roasting temperature is 1350°C and molecular proportion of Al₂O₃/BaO is 1.1. The bulk density of barium aluminate is 1.5g/cm³; average particle size is 89.808μm; surface mean size is 65.915μm; and the specific surface area is 0.0246016m²/g.

Abstract: We have synthesized mesoporous SiO₂ (MCM-41) and TiO₂ encapsulated bimetallic Cu-Ni nanocatalysts using an optimized one-pot hydrothermal procedure. The catalysts were characterized using BET, XRD, TGA-DSC and HRTEM techniques. While bimetallic Cu-Ni/MCM-41catalysts have high surface area- 634-1000 m²/g, Cu-Ni/TiO₂ yields surface area of 250-350 m²/g depending on the metal loading (5-10 wt%). The XRD studies confirmed a long range ordered structure in Cu-Ni/MCM-41 and the presence of the catalytically active anatase phase in the crystalline Cu-Ni/TiO₂. The results from HRTEM studies were consistent with the mesoporosity of both supports. These catalysts were tested for methanol conversion and H₂/CO selectivity via steam reforming of methanol (SRM) reactions in a fixed bed reactor. There is a distinct difference in the performance of these two supports. Bimetallic 3.33%Cu6.67%Ni/TiO₂ catalyst showed an impressive 99% H₂ selectivity at as low as 150°C and a maximum conversion of 92% at 250 °C but 3.33%Cu6.67%Ni/MCM-41 catalyst did not show any H₂ selectivity at 150°C and only ~12% conversion at 250°C. The effect of each support and relative metal loadings on the activity and selectivity of the SRM reaction products at different temperatures is discussed.