Advanced Materials Research Vols. 834-836

Abstract: According to physicochemical property of molybdenum, the application of molybdenum is elaborated from three aspects that are molybdenum element, molybdenum alloys and molybdenum compound; The distribution of nature resource of molybdenum at abroad and home and the source of recoverable resources are summarized; the production method of ammonium molybdate is introduced which are oxidation roasting and wet oxidation, and the extracting method of molybdenum is introduced which is reduction method; the development tendency of molybdenum is pointed out.

Abstract: This paper presented a modified Yoshida-Uemori constitutive model to describe the stress-strain responses of tempered sorbite steel under cyclic loading. In this model, a mutational yielding surface and an isotropic hardening surface were defined in stress space and strain space for the description of Bauschinger effects, respectively. Then this model was used to simulate tension-compression tests of Weldox960 steel and study the springback and reduction of thickness in cold-bending. Results obtained from the experiment and simulation show that this modified model is valid in predicting cold-bending forming and springback.

Abstract: AA6016 aluminum alloy with a strong β fiber rolling texture was cold rolled to different reductions by means of a special deformation method (side rolling in Chinese). The texture development during side rolling was investigated by X-ray diffraction. The typical B, S and C orientation on the β fiber are transformed into the B'{111}, S'{22 17 9} and C'{011} orientations, respectively. The results show that these orientations are unstable and gradually rotate to the B orientation in the new sample reference frame.

Abstract: The factors on the impact of heavy metals migration (Nickel (Ni) and Chromium (Cr)) of stainless steel choppers were studied in this paper, including chemical composition of stainless steel choppers and surface treatment, sample soaking mode, soaking time and soaking temperature. The results shown that, which did not exist linear relationship between the chemical composition and heavy metal migration. Instead, the surface treatment process was the major impact factor. The heavy metals migration of stainless steel choppers reduced after surface treatment processes. Than the direct integral soaking mode, the slices soaking mode had a larger migration of heavy metals. The Nickel (Ni) and Chromium (Cr) migration increased with the immersion time and the immersion temperature. In summary, by controlling the processing and use method of the chopper can effectively control the migration of heavy metals.

Abstract: Microstructure and mechanical properties of 2024 aluminum alloy flange semi-solid thixoforging by changing cavity was investigated. Theoretical calculation and forming test were adopted to study the preparation of flange. It is concluded that the influence factors of forming limit of flanges are radical load P, friction τ and thickness t by theoretical calculation. The results show that it is uniform in the process of forming. Microstructure and mechanical properties of flange have been improved significantly with the increase of the radical load. Way of variable cavity realized the real plastic deformation, which results in high mechanical properties of flange. The flange could obtain fine microstructure with grain sizes of 20~30μm, tensile strength of 433MPa and elongation of 10.1%, with changing amount of 30MPa. The results indicate that the microstructure and mechanical properties could achieve forging requirement and be controlled using changing cavity.

Abstract: The hot deformation behaviors of the nickel-base superalloy GH4169 have been studied by isothermal constant true strain rate compression testing at 950°C-1150°C, 0.01s^-1-10s^-1 and the height reduction 50%. The processing maps of GH4169 alloy have been constructed at different strains on the basis of testing data using a dynamic materials modeling. The maps exhibited two domains: the first at 950°C - 1100°C and strain rate higher than 0.1s^-1, with a peak efficiency of power dissipation of 0.1, and the second at 950°C-1100°C and strain rate lower than 1s^-1, with a peak efficiency of power dissipation of 0.4 and the strain rate of 0.01s^-1. On the basis of microstructure observations, the first exhibits adiabatic shear bands, which called instability domain, the second represents fine recrystallized grain structures, which called stability domain. The optimal hot-working parameters are at 1050°C, 0.01s^-1.

Abstract: The effect of different oxygen annealing treatments on the structural and electrical properties of samples of the high temperature superconductor YBa₂Cu₃O_7δ (YBCO) synthesized by a biomimetic method has been studied. By oxygen annealing, the oxygen deficiency resulting from the synthesis in air can be adequately compensated. A two-stage annealing process including a high temperature step results in a sharper superconducting transition and higher critical current density of the YBCO than annealing only at low temperature, due to the additional elimination of carbon residues from the biopolymer additive. To avoid the formation of impurity phases resulting from decomposition of the YBCO during the high-temperature anneal, careful pre-treatment by rinsing the as-synthesized YBCO with distilled water to remove residual NaCl is necessary.

Abstract: Sewage Scaling in the process of sewage transfer in gas field containing hydrogen sulfide is one of the major problems in the gas field production. So to study the scaling mechanism of sewage containing hydrogen sulfide is necessary and can provide thought for antiscale of transfer pipelines. The study shows that as a result of the corrosion effect of hydrogen sulfide, it makes increases of roughness in the pipe inner surface and increases of small particles in the sewage, promotes crystallization of the scale crystal, and changes the structure and size of the scale crystal. The slow oxidation of hydrogen sulfide produces elemental sulfur particles, promotes the crystallization of more scale crystals, and increases the amount of scale formation. The changes of pH value in the sewage change the concentration of hydrogen sulfide ions in sewage containing hydrogen sulfide, change the sewage corrosion, and thus change the composition of sewage scaling. Under the condition of containing hydrogen sulfide, sewage presents the characteristic of corrosion first and scaling later,then corrosion promotes the scaling, and the scale contains more corrosion products.

Abstract: Double conjugate addition of thiols with dienones was catalyzed by amino acids at room temperature in methanol, to afford the corresponding addition product in good to excellent yields.

Abstract: Silica sol was prepared using TEOS as the precursor and HCl as the catalyst by sol-gel process. The effects of the ratio of the reactants and temperature on the viscosity of SiO₂ sol during the sol-gel processing were investigated and the reaction activated energy was calculated. With the increase of the EtoH/TEOS ration, the viscosity reduced, a higher viscosity can be obtained at the H₂O/TEOS ratio of about 8. The viscosity increased and the gel time decreased with the increase of temperature, the activation energy of the formation of gel was about 73.8kJ/mol.