Advanced Materials Research Vols. 239-242

Abstract: The present investigation aims at elucidating the photoluminescence (PL) behaviour of Tb³⁺ doped SiO₂–M₂O₃ (M=Al, Ga)–LiF–CaF₂ optical glasses. The absorption spectra of these glasses have revealed the absorption bands due to ⁷F₆ → (⁵L₈, ⁵G₃, ⁵L₉, ⁵G₄, ⁵D₂, ⁵G₅), ⁵L₁₀, (⁵G₆, ⁵D₃) and ⁵D₄ transitions. The Tb³⁺ excitation bands are assigned to the electronic transitions of 4f⁸ → 4f⁷5d¹ and 4f⁸ → 4f⁸. The PL spectra with the excitation wavelength 378 nm recorded at room temperature of these glasses have exhibited the following emission transitions: ⁵D₄ → ⁷F_J (J = 6, 5, 4, 3). An attempt has also been made to throw some light on the relationship between the structural modifications and luminescence efficiencies of both the two glasses. And found the fluorescence intensity of 543 nm emission in SGLCT is 46% higher than that in SALCT due to the different metal oxides viz., Ga₂O₃ and Al₂O₃.

Abstract: The role of xanthine in the growth process of Au nanoparticles (AuNPs) was clarified by Uv-vis absorption spectra, resonance light scattering (RLS) spectra, cyclic votlammetry (CV), and differential pulse voltammetry (DPV). In a growth solution containing 0.01 M phosphate buffer solution (PBS, pH 7.4), 24.3 μM HAuCl₄, and 2 mM cetyltrimethylammonium chloride (CTAC), the AuNPs were produced by tannic acid (TA) reduction. The growth of AuNPs was inhibited by the addition of xanthine. The plasmon absorbance band of AuNPs is blue shifted, indicating that larger sized AuNPs were grown in the presence of xanthine. Both the absorbance at 555 nm and RLS intensity at 652 nm of the grown AuNPs decreased linearly with increasing concentrations of xanthine. The linear regression equation are A=1.865−0.016 C_xanthine and I=397.8−4.617C_xanthine for absorbance and RLS intensity, respectively. The results of CV and DPV reveal that the inhibition effect of xanthine on the growth of AuNPs may attribute to the formation of xanthine-Au(III) complex. The conditional stability constants of the complexes were determined to be 2.22×10⁵.

Abstract: This study had conducted a comparative study on storage navel orange with tourmaline carton and ordinary carton,The effect of preservation with tourmaline on the storage navel orange had been discussed through the change trend of main organic content,weightlessness rate and decay rate during storage of navel orange.The results showed that the weightlessness rate of navel orange storage by ordinary carton was 5.26%,which was greater than the 4%,that was to say,the value of navel orange had been lost;however,the tourmaline carton,which played a good role in the fresh storage of navel orange .

Abstract: A rotating gas bubble stirring technique with specially designed equipment has been developed for the production of light alloy semi-solid slurry. The equipment was specially designed to have temperature, rotation speed and gas flow rate control functions. An Al-Si aluminum alloy was applied as the experimental material. The results showed that large volume of semi-solid slurry could be achieved with the actual stirring temperature of 4 °C to 20 °C below the liquidus temperature of the alloy, and the rotation speed of 195 r/min, and the gas flow rate of 2 L/min. A strong convection and weak stirring effect which was induced by the rotating gas bubbles in the melt was founded responsible for the formation of the semi-solid slurry.

Abstract: The objective of this study is to find effective and economical cement grout system for preventing corrosive gas. In this paper, in order to resist the corrosion of the cement sheath by acid gas, a new corrosion resistant agent denoted as FH-1 has been added into the cement grout. A series of cement blocks formed by cement system with different additives quantities have been obtained. The permeability, compression strength and corroding depth of these cement blocks have been investigated. The microstructure of cement blocks has been analyzed by scanning electron microscope (SEM) and the mechanism of corrosion resistant of FH-1 has been discussed. The FH-1 shows excellent resistance to corrosion against CO₂, and H₂S gas.Therefore the optimal corrosion resistant cement grout systems were obtained.

Abstract: The potentiodynamic polarization and cyclic voltommogroms studies were carried out on the copper with micro-addition of Cr and Zr in solutions of 0.5M NaCl, 0.5M NaOH and 0.5M HCl at room temperature. The corrosion resistance of pure copper is deteriorated with addition of the alloying elements Cr and Zr. Significant reducing in the corrosion resistance is observed when Cr and Zr are added simultaneously. Moreover, the lowest corrosion current density is obtained in the NaCl solution followed by the NaOH solution and HCl solution. Compared with the different effect on the passive layer in the NaCl solution, the micro-addition of Cr and Zr leads to the increasing of the corrosion resistance for the passive layer in 0.5M NaOH solution and 0.5M HCl solution.

Abstract: In order to reveal the forming laws，eliminate the forming defects appearing in the typical aluminum alloy web-rib parts，two types of preforms have been used in the final forging with numerical simulation software.Based on the simulation，the comparisons of metal flow，effective strain distribution are obtained between the two types of preforms applied in the final forging process，the forming laws of a symmetrical rib-web component have been obtained ,and the forming mechanism of defects often happened in web- rib parts also has been analyzed,the relationship between the fillet radius and metal flow velocity/ final load was obtain. The results show that the fiber breaking,vortex could be avoided，a high forming quality of rib-web part could be gained by the method of using the thin web-high rib preform in finish-forging.

Abstract: In this thesis, based on the low-carbon bainitic steel HQ785, isothermal transformation tests are carried out on the Gleeble-3500 thermo-mechanical simulator under uniaxial external tensile stress state. The fully immersed accelerated corrosion tests for the specimens, with different microstructure after phase transformation are carried out. The corrosion behavior of experimental steel is evaluated, combing with OM, SEM, weight loss method and electrochemical method. The results show that the shape of phase transformation microstructrue varies from granular to lath with the increase of external tensile stress. The corrosion resistance of which is better than that of granular bainite without stress. The sample with rusty layer after full immersion seawater corrosion shows good protectiveness.

Abstract: Multi-way tube on air conditioning header is considered as the research objective .Finite element simulation method is utilized to simulate and analyze the deformation process of metal. Through analyzing the distribution law of velocity on work piece neutral plane and displacement law of typical nodes, common law in deformation process for metal flow was revealed. Results suggested that: metal which is on terminal supplementary zone conspicuously flows along horizontal. Metal which is on forming zone conspicuously flows along bulge, metal which is between bulges flows little, these laws provide a reference for the choice of forming technology.

Abstract: The effects of the ratios of natural rubber latex (NRL)and chloroprene rubber latex(CRL) and the type of compatibilizer on physical and mechanical properties of latex film were researched.The oil resistance of vulcanized latex film was tested. The compatibility of the latex blends was also analyzed by TG/DTG method.The results showed that properties of latex film were best when ratio of NRL/CRL was 75/25. As the CRL content increased, oil resistance of latex film was improved. Epoxidized natural rubber latex improved compatibility of NRL and CRL blends.