Key Engineering Materials Vol. 636

Abstract: The powder of Li_1.4Al_0.4Ti_1.6 (PO₄) ₃ has been synthesized by a solid phase reaction between Li₂CO₃, Al₂O₃, TiO₂ and NH₄H₂PO₄. Sodium removal was studied in an extensive series of tests involving different ionic exchange process variables such as time and temperature. The results indicate that the Na/Li ion exchange reaction rate increased obviously with increasing temperature, and the Na/Li ion exchange kinetics process of Li_1.4Al_0.4Ti_1.6 (PO₄) ₃ in lithium chloride solution could be shown approximately by the equation of JMAK. Furthermore, it is concluded that the Na⁺-removed materials obtained from NASICON-type ceramics synthesized can serve as selective Na⁺ absorbent due to its high selectivity and larger ion exchange capacity.

Abstract: Using Fe (NO₃)₃⋅9H₂O, Y(NO₃)₃⋅6H₂O and citric acid as the main raw material, the YFeO₃ nanoparticles were synthesized by ultrasonic assisted process and calcination. The YFeO₃ nanoparticles were characterized by thermogravimetry and differential thermal analysis (TG-DTA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible diffuse reflectance spectroscopy (DRS). The results show that the perovskite structureYFeO₃ (YFeO₃-800) can be obtained through the calcination of ultrasonic processed YFeO₃ precursors at 800 °C, and the resulting product has a particle size of 70 nm and an optical band gap of 2.0 eV. Consequently, the YFeO₃-800 nanoparticles show high photocatalytic activity for decomposition of methyl orange under visible-light irradiation.

Abstract: Molecular structural mechanics based finite element method has been applied to study the effects of two types of Stone-Wales (SW) defects and vacancy defect on elastic buckling properties of single-layered graphene sheets (SLGSs). The defect effect factors of critical buckling stresses are calculated for the defective SLGSs with different chirality and geometrical dimensions. It is proved that defect effect factors are size-dependent and chirality-dependent. The results show that the vacancy defects will always weaken the SLGSs’ stability, and two types of SW defects have different effects on zigzag and armchair SLGSs. What’s more, the positions of defects also have remarkable influence on the critical buckling stress of SLGSs.

Abstract: The size controlled colloidal gold nanoparticles were prepared by sodium citrate photochemical system. The size and morphology of the gold nanoparticles were characterized by TEM and UV-Vis spectroscopy. nanoAu/C catalysts were obtained by loading the gold nanoparticles. The catalysts were used for the catalytic oxidation reaction of glyoxal and glucose in liquid phase. The research results showed that the catalysts had higher catalytic activity, and this preparation method is successful.

Abstract: This work is directed towards the synthesis of multifunctional nanoparticles of Fe₃O₄/Au nanocomposite, aimed at ensuring the magnetic and optical properties of magnetic-gold nanocomposite simultaneously. The nanoparticles showed good response to externally applied magnetic fields. The UV–vis spectroscopic examination reveals the maximum adsorption at ∼400 nm. Finally, the Fe₃O₄/Au nanoparticles were applied for detection mercury (II) ions in water solution.

Abstract: Surface modification of nanoSiO₂ was carried out in ethanol solution with two different silane coupling agents, 3-aminopropyltriethoxysilane (KH-550) and 3-methacryloxypropyltrimethoxysilane (KH-570), respectively. The structure and performance of modified nanoSiO₂ were analyzed by infrared spectroscopy, surface hydroxyl number and conductivity. The influence factors as stirring time, temperature and modifier amount on modified performance have been discussed. The results shown that optimal modification conditions with KH-550 and KH-570 were as follow: temperature 75 ^oC, stirring time 4 h and the modifier 5% (w/w). Surface hydroxyl numbers were 0.7826×10²⁰/g and 0.7525×10²⁰ /g, conductivity were 32μs/cm and 92μs/cm, respectively. The modification effect of nanoSiO₂ with KH-550 was better than KH-570.

Abstract: Ni-doped copper nitride films have been prepared by co-sputtering of Ni and Cu targets. The addition of Ni to Cu₃N films reduced the intensity of the (111) diffraction peak, and lead a little angular shifts of the peaks. The films showed a large difference in reflectance in the infrared and visible before and after thermal decomposition, which is applicable to optical recording media. The films change from a semiconductor to a conductor with the increased ratio of Ni in Cu₃N films.

Abstract: In this paper the new process of arc spraying was researched on CuCo2Be alloy surface,the high strength and high wear resistance Cr3C2/Fe coating were prepared on CuCo2Be alloy surface by adopting a series of different arc spraying process parameters. Based on the test the arc spraying process parameters was optimized, the optimized result was: spraying voltage was 38V, the current is 180A, spraying distance was 150mm, spraying air pressure was 0.7MPa, the bonding strength of the coating and the substrate was 30.5MPa; and the thermal shock resistance of coating Cr3C2/Fe was studied in detail by different spraying process parameters, it was showed: thermal shock resistance of the coating was best by spray low voltage and low current process. By using microhardness tester, super depth of field microscope, SEM, EDS and XRD, mechanical properties, microstructure, phase composition and its content distribution of Cr3C2 / Fe coating were studied, the study results were showed: the micro-hardness of coating was 992.75HV, coating was a typical lamellar structure, and a small amount of pore and oxides in the coating; the mainly phase of coating included: Fe, Fe-Cr, C0.14 Fe1.86 and Fe7C3.

Abstract: The prepared ZrB₂/6063Al composites were forged on the small tonnage forging air hammer machine. The results indicate that the forged ZrB₂/6063Al composites’ reinforced segregation of particles and the uniformity of the materials organization were improved; the grains were refined and the tensile strength ,yield strength and hardness were improved after ZrB₂/6063Al composites forged, but the plasticity of the composites were decreased.