Advanced Materials Research Vol. 937

Abstract: First-principles calculations based on density functional theory have been used to study the surface energies of the rutile TiO₂(110) and (011)-2×1 surfaces. We investigate the effect of the slab thickness on the predicted surface energy and find that slab thicknesses of at least 5 layers are necessary to converge the surface energy to within 0.01 J/m² for both rutile TiO₂(110) and (011)-2×1 surfaces. For the rutile TiO₂(110) surface, it should be noted that the surface energy oscillates with the number of layers (odd-even oscillations). However, the calculated surface energies of the rutile TiO₂(011)-2×1 surface are closer to the linear relationship for the number of layers larger than 4. Finally, our calculated results indicate that the rutile TiO₂(011)-2×1 surface has a significantly higher surface energy than the rutile TiO₂(110) surface.

Abstract: To study optimum inclusion process conditions for essential oil from perilla and Pericarpium Citri Reticulatae in Baokening granule,the utilization ratio of volatile and the inclusion rate were determined to evaluate process conditions, and the condition was optimized with orthogonal design by the liquid-phase method in aqueous solution. The experiment results showed that the optimum preparation conditions for inclusion were established as: oil: ß-CD was 1:8, and ratio of amount of water to ß –CD was 10. The inclusion temperature and time were at 40°C and for 180 min. The yield is high in such optimum process condition and the inclusion effect is good.

Abstract: According to the characteristics of high strength weathering steel, this paper designs to develop anexperimental steel S450EW with yield strength higher than 450MPa.Through the study,it has been found that with decreasing cooling rate, the organizational changed largely, while ferrite and pearlite gradually transformed to martensite and a small amount of ferrite, then finally tomartensite organization.It has also been found that the crystal size decreased, and the experimentalsteel also precipitated a rectangular second phase particles of (NbTi) CN phase and TiC, which were sparsely distributed with the size of 100 ~ 300nm and below 30nm, while some phases were distributedasa number of strips in the grain boundary which mainly are C, Fe, Cr.

Abstract: In this paper, the yield strength of a kind of carbide strengthened molybdenum (Mo) alloy has been investigated at both room and elevated temperatures. OM image showed that the sintered Mo alloy has an average grain size of ~20 μm. SEM image of the fracture surface of the sintered Mo alloy after tensile deformation to facture showed that intergranular fracture is the dominant mechanism at room temperature. A constitutive model has been developed to simulate the yield strength of Mo alloys at both room and elevated temperatures. It has been shown that the evolution trend of the yield strength predicted by the constitutive model broadly agrees with the experimental counterparts. The simulation indicated that creep dominates the deformation when the temperature is above 1200 K, while dislocation overcoming the obstacles through thermal activation dominates the deformation when the temperature is below 1200 K.

Abstract: Iron titanate photocatalysts were synthesized by the high-energy ball milling method with titanium ore as the starting material. X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), thermal gravity and differential thermal analysis (TG-DTA), UV-visible diffuse reflectance absorption spectra (UV-Vis), photoluminescence emission spectra (PL) and photocatalytic degradation measurement were conducted to characterize the structure, surface status, UV-visible light response and performance of the obtained sample. After low temperature calcination (above 400 oC), the photocatalytic activity of iron titanate catalyst decreased gradually, which was mainly due to the decrease of surface hydroxyls and reactant adsorption capability.

Abstract: The power at 400 Watts Nd: YAG laser is used for laser brazing on copper. By improving the process parameter,a good joint will be achieved. Because of the stainless steel material, more lasers will be absorbed, which can actualize the small power laser weld the thicker red copper. The test of the joint pull shows that the tensile strength of the copper brazing joint can reach more than 80% of its base mental.

Abstract: The effects of the thermal cycling on the coefficient of thermal expansion (CTE) and microstructure of the hypereutectic Al-Si alloys were investigated. The hypereutectic Al-Si alloy was produced by spray-forming and extruding process. Experiment results showed that the distribution of Si in Al matrix is uniform for the Al-Si alloy. The primary Si phase grew gradually during the thermal cycle. There is no remarkable change of CTE during thermal cycling for both materials at the same temperature range. The CTE of Al-Si alloy decrease with increasing on thermal cycling temperature up to 300°C due to the compressive thermal stress in the alloys.

Abstract: Experimental investigations of fatigue cracking behavior of LC9 aluminum alloy (AA LC9) subjected to elevated temperature were conducted with scanning electron microscope (SEM). Results indicate elevated temperature is important for the fatigue crack growth of AA LC9. Based on small crack growth, crack growth rate for AA LC9 is characterized.

Abstract: Wetting and spreading ability of Ag-Cu-Zn filler and Ag-Cu-P filler on copper surface under heat treatment furnace was studied. The microstructures of brazed joints of Ag-Cu-Zn and Ag-Cu-P filler under the same parameter were also observed. The microstructure shows that the wetting ability of Ag-Cu-Zn filler on the copper surface is better than Ag-Cu-P and its structure is uniformed and regulated. It is founded that there were obvious dissolution and diffusion between base metal and filler for the copper/Ag-Cu-Zn/copper joint, there were white and black eutectic structure formed in the joint interface.

Abstract: The research on the fatigue life of butt welded joint has important significance to hoisting equipment’s design, development and using safety. This paper conducted a study on fatigue properties of the most widely used joint at hoisting equipment-steel Q235 butt welded joint’s, based on the improved linear equivalent structural stress method, the stress of the weld joint can be obtained, and the master S-N curve of Q235 weld joint be acquired through fatigue test, thus the joints stress distribution under different stress environment can be gained through improved linear equivalent structural stress calculation and the fatigue life of the joint can be realized at the master S-N curve. The stress distribution situation and the fatigue life of butt welded joint can be calculated by integrated finite element software, this have profound reference significance to hoisting machinery industry.