Advanced Materials Research Vols. 785-786

Abstract: In this paper ammonium molybdophosphate (AMP) and ammonium molybdophosphate-zirconium phosphate-silica (AMP-ZrP-SiO₂) were prepared as trace Rb⁺ and Cs⁺ adsorbents. The two showed good adsorption performance for trace Rb⁺ and Cs⁺ when dealing with the salt lake brine. AMP-ZrP-SiO₂ has better hydraulics performance, and is more suitable for column adsorption. The adsorption mechanism, enthalpies (ΔH⁰), Gibbs free energies (ΔG⁰), and activation energies (E_a) of Rb⁺ and Cs⁺ from salt lake brine by the two adsorbents were investigated. The results show that the adsorption processes of Rb⁺ and Cs⁺ on AMP and AMP-ZrP-SiO₂ are spontaneous and endothermic. The adsorption order of various ions on the two adsorbents is Cs⁺>Rb⁺>K⁺>Mg²⁺>Na⁺>Li⁺ by comparing their Gibbs free energies. Through the analysis of activation energies indicates that AMP-ZrP-SiO₂ is more efficient than AMP in the enrichment process of trace Rb⁺ and Cs⁺.

Abstract: The pure and Zr-doped BiFeO₃ thin films were fabricated on Pt/TiO₂/SiO₂/Si substrates by sol-gel method. The microstructural characterization revealed a phase structural transition from rhombohedral structure to tetragonal structure in Zr-doped BiFeO₃ thin films. Compared with pureBiFeO₃ thin film, the Zr-doped BiFeO₃ thin films showed better dielectric and leakage current characteristics. The mechanism associated with the enhancement of the electrical properties of the thin films is also discussed.

Abstract: Two-membrane-pieces sensitizing method and the corresponding equipments were developed to prepare cyanines sensitized nanoTiO₂ photo anode materials. The cyanines were synthesized from N-p-carboxybenzyl-2,3,3-trimethyl-3H-indoleninium-5-sulfonate potassium and squaric acid or 2-chloro-1-formyl-3-(hydroxymethylene) cyclohex-1-ene. The maximum UV-Vis absorption wavelengths of them were 631 nm and 782 nm, respectively. The nanoTiO₂ thin films were prepared on ITO conductive glass from tetrabutyl titanate by sol-gel technique, and were sensitized with the dyes by two-membrane-pieces dye sensitizing method or immersion sensitizing method. Compared with traditional immersion sensitizing method, two-membrane-pieces sensitizing method was an environmentally friendly and economical process due to less dye consumption and less waste formed.

Abstract: Two containing fluorine functional ionic liquids (ILs) (1-aminoethyl-3-methyl imidazolium trifluoroacetic acid salt ([aemim] [CF₃COO]) and 1-aminoethyl-3-methyl imidazolium trifluoromethane sulfonic acid salt ([aemim] [TfO])) were synthesized and the samples were characterized by means of FTIR, ¹HNMR respectively. The densities, viscosities, and electrical conductivities of the two samples were measured over the temperature range T = (303.15-333.15) K at atmospheric pressure. The solubility of CO₂ in the two samples were investigated at temperature from 303.15 to 333.15 K and pressure from 0 to 7.14 MPa. Results showed that the maximum solubility of CO₂ in [aemim] [TfO] was 0.759 (mole fraction) at 7.01 MPa and 323.15K, and the which of [aemim] [CF₃COO] was 0.646 at 6.49 MPa and 313.15 K. The influence of the temperature and CO₂ partial pressure on the process of CO₂ absorption was discussed. The CO₂ solubilities in different ILs were also compared. The Henry's constants and infinite dilution partial molar volumes for the ILs+ CO₂ systems were obtained.

Abstract: The initial surface reaction mechanisms of atomic layer depositionTiO₂ using Ti (OCH₃)₄ and H₂O as the precursors are investigated by density functional theory. The ALD process is divided into two half-reactions, i.e., Ti (OCH₃)₄ and H₂O half-reactions. The adsorption of Ti (OCH₃)₄ on OH/Si (100)2×1 surface is exothermic. However, the overall reaction of Ti (OCH₃)₄ is endothermic. In addition, H₂O half-reactions are endothermic and thermodynamically unfavorable.

Abstract: The submicron structural WC-12Co coatings were deposited by a high-velocity oxy-fuel (HVOF) system from agglomerated WC-12Co powders with carbide grain size of 0.7~0.9μm in this study. Effects of HVOF spraying parameters on the microstructure and properties of submicron structural WC-12Co coatings were examined. The results showed that both the fuel flow rate and spraying distance influenced significantly the microhardness and porosity of coatings, and cooling condition also had a few effect on the porosity of coatings. Through a series of experiments, the spraying parameters for the WC-12Co coatings preparation were optimized as follows: propane gas pressure was 0.65 MPa, propane flow rate of 16.7 L/min, oxygen pressure of 0.7 MPa, oxygen flow rate of 100 L/min, spraying distance of 270 mm and with compressed air cooling. The porosity of WC-12Co coating sprayed at the optimum parameters was lower than 1%, and its microhardness was HV_0.1 1141±67.

Abstract: The cyclic oxidation behavior of Co-10Cr-5Al alloys with and without Y in atmosphere at 800 °C was investigated. The addition of 0.3 at.% Y increased the oxidation rate of the alloy and changed the behavior from irregular oxidation kinetics to approximate parabolic rate law. The scales grown the alloys with and without Y were both composed of an outer Co₂O₃ layer and an inner complex layer of Al₂O₃, Co₂O₃ and Cr₂O₃, except that the addition of Y impaired the adhesion of the scale. Over-doped Y agglomerated in local zone plays an adverse role in the oxidation process by accelerating the oxidation rate.

Abstract: This paper presents the results of research influence nitriding in electrolytic plasma on the tribological properties of low-alloy 40Cr steel. It is shown that the process of electrolytic plasma nitriding can significantly increase the wear resistance of the samples 40Cr steel. Found that after nitriding component adhesive wear mechanism is changed to abrasion.

Abstract: Decorative Ni-Cr plating on ferritic stainless steel was exposed to pure carbon dioxide (CO₂) at 200 and 300oC for 180 hours under continuous and cyclic oxidation tests. After oxidation test, weight changes of samples exposed to CO₂ were found to be less than that of samples exposed to air. However, weight changes were dependent on temperature and oxidation conditions. Heat-quench test was operated at temperature of 200-500oC for determining adhesion behavior of decorative Ni-Cr plating. From the heat-quench test, it revealed that adhesion ability between Ni-Cr plating layer and substrate increased with thickness of Ni pre-plating layer at temperature of 200 and 300°C. But, at temperature above 300°C, the adhesion ability increased with surface roughness of substrate before coating. In order to achieve important properties of decorative Ni-Cr plating, i.e., oxidation resistance, beautiful appearance and good adhesion, surface of substrate was necessarily prepared under medium roughness and then it was pre-plated with the thickest Ni layer before Cr coating was applied.

Abstract: The objective of this research is to study wear behaviors of TiN, nanolaminated AlCrN and nanocomposite TiAlSiN coated on cemented carbide end mill deposited by cathodic arc physical vapor deposition methods in comparison with uncoated end mill. Wear behaviors were investigated by nanoindentation hardness test, scratch test and cutting test. Oxidation test was also done in air at temperatures of 700°- 900°C in order to evaluate resistance of oxidation. In the nanoindentation hardness and scratch tests, nanocomposite TiAlSiN coating exhibited higher hardness than TiN and nanolaminated AlCrN coatings. The nanolaminated AlCrN coating represented the highest adhesion ability in terms of critical load and the lowest coefficient of friction in comparison with the TiAlSiN and TiN coatings, respectively. The cutting performance, represented in terms of maximum flank wear as a function of cutting length, was found to be highest in the AlCrN coating. Oxides of these coatings, i.e., TiO₂ for TiN, TiO₂ for TiAlSiN and Cr₂O₃ for AlCrN, generated at different temperatures of 700°, 800° and 900°C, respectively. From all of results, it is obvious that the AlCrN coating exhibited more excellent wear resistance and oxidation resistance than the uncoated end mill, TiN coating and TiAlSiN coating.