Advanced Materials Research Vols. 791-793

Abstract: A finite element model implemented with a progressive damage propagation mechanism was generated to study the mechanical behavior of stiffened composite panels under uniaxial tension. Typical damage modes including fiber breakage, matrix crushing and delamination were considered in the model. Failure criteria with corresponding stiffness degradation technologies was used to predict the initiation and evolution of intra-laminar damage modes by a user-defined subroutine. Cohesive elements with thickness of 0.01mm were defined along the interface areas between the filler and the adjacent laminate layers for predicting the initiation and propagation of delamination. Corresponding tests on composite stiffened panel with a web cut-out were conducted. A good correlation between the numerical results and test data was obtained, which validated the finite element models. Both the numerical and experimental results conclude that the delamination in the flange around the cut-out region is the most critical failure mode for the composite stiffened panel under the uniaxial tensile load.

Abstract: The diameters of 22 ionic liquids and radius of their cations and anions were calculated by DFT method. The calculation method of distance between cation and anion was set up according their diameters and radius. The relationship between glass transition temperature of ionic liquids and above parameters was investigated using multiple linear regression method and the correlation coefficient was 0.96. The model provided theory methods to calculate glass transition temperature of different ionic liquids.

Abstract: In this paper, hydroxylated CNTs/Fe₂O₃ precursors were prepared on the basis of Fenton reagent treatment using aqueous ammonia (NH₃H₂O), sodium carbonate (Na₂CO₃) and urea (CO(NH₂)₂) as precipitants. And then three kinds of hydroxylated CNTs/Fe₂O₃ compound particles were obtained by calcining the precursors at 523K for 2h. The change of hydroxyl group, phase structure, morphology, thermogravimetric behavior, magnetic property and electrical conductivity of the compound particles were investigated, respectively. The results show that hydroxyl groups exist on surface of CNTs, and Fe₂O₃ particles in composite particles exhibit high purity and integrated crystalline structure. For NH₃H₂O precipitant, α-Fe₂O₃ particles is produced with crystallite size of 62.5nm and no saturation magnetization (Ms). For Na₂CO₃ precipitant, γ-Fe₂O₃ is produced with crystallite size of 37.6nm and Ms of 10.5emug^-1, and the compound particles are drastically agglomerated. For CO(NH₂)₂ precipitant, γ-Fe₂O₃ is produced with crystallite size of 35.1nm and Ms is 9.7 emug^-1, and the compound particles are homogeneous with the lowest volume resistivity of 100 Ωcm.

Abstract: The process of the metal liquid flows in the die cavity, with finite element method used, was simulated in the article. The article fully introduced the foundation of the die cavity, definition of the material parameters, model meshing and boundary conditions setting. Conclusion included velocity and pressure distribution of the liquid. The reasons of the casting defect were detected according to the analysis, which provided a theoretical basis for practical production in order to improve the quality of the products.

Abstract: The tempering temperature on microstructure and mechanical properties of 35CrMnSiMo cast steel are studies in this article. Results showed that 880°C×30min 35CrMnSiMo cast steel after quenching water, hardness up to 49.6HRC, reached 39.04 J/cm² toughness. Tempering temperature selected 200°C, 400°C and 600°C, respectively with the increase of the tempering temperature plummeting hardness and impact toughness are on the rise, but at 400°Cdecreased. Photos can be seen from your organization after quenching, which contains a lot of lath martensite, a small amount of lump some residual austenite and martensite, 200°C tempering martensite has been reduced, some of carbide precipitation into tempered martensite. Tempering of martensite quenching slats or flake, it is made of flake martensite and small ξ carbide distribution.

Abstract: A new Ti-based amorphous alloy Ti₃₅Zr₂₁Cu₄₀Si₄ with about 80 μm thickness and 5~8 mm width was fabricated by melt spinning method. The phase structure and thermal stabilities of the Ti₃₅Zr₂₁Cu₄₀Si₄ amorphous alloy were investigated by the X-ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. The Ti₃₅Zr₂₁Cu₄₀Si₄ amorphous alloy was cultivated in the simulate body fluid (SBF) for 15 days. And the blood compatibility was evaluated by dynamic clotting time and hemolysis rate test. The Ti₃₅Zr₂₁Cu₄₀Si₄ alloy exhibits fully amorphous phase and high thermal stability with a supercooled liquid region (ΔT_x) of 80K. The Ca phosphates depositions on alloy surfaces were gained after 15 days. Moreover, n (Ca)/n (P) atom ratio of the deposition is about 1.65/1, which approaches to that of human bone 1.66/1, suggesting that the Ti₃₅Zr₂₁Cu₄₀Si₄ amorphous alloy is with an excellent biocompatibility. The Ti₃₅Zr₂₁Cu₄₀Si₄ amorphous ribbon has lower hemolysis ratio of 0.562%, which can reduce wrecking degree of erythrocytes, compared with medical standards of the hemolysis rate (less than 5%). These are favorable for application to biomaterials.

Abstract: This paper mainly studied the high temperature quenching oil quenching, tempering temperature on the influence of high strength steel mechanical properties of wear resistant. The results show that high strength and toughness wear-resistant cast steel with 880°C× 30min after oil quenching, the hardness of 38.6HRC steel, the impact toughness value reaches 40.18J/cm². After 200°C, 400°C and 600°C tempering, with the increase of the tempering temperature, the hardness decreased linearly, as by 600°C tempering, the hardness has been reduced to 22.3HRC. Impact toughness with the tempering temperature, the overall upward trend, the impact toughness of some reduced at 400°C, the highest impact toughness value reaches 113.34J/cm². From the fracture morphology can be seen, with the increase of tempering temperature, ductile fracture increased, by 600°C tempering is dimple fracture, obviously can not see the traces of brittle fracture.

Abstract: The Cu-based SS-O solar spectrum flat-plate selective absorption coating system was prepared by the method of direct current reactive sputtering coating films, in which, two layers are SS-O absorbing layer and one is Si-O anti-reflection layer. The reflectance spectra of the absorption coating system was measured by UV3600 spectrophotometer, the reflectance and absorptance of the absorption layer and the anti-reflection layer were calculated, and certain experimental tests were conducted on the prepared absorption coating system in terms of the salt spray resistance performances, thermal stability and damp heat stability. The results show that the SS-O selective absorption coating which was prepared by magnetron sputtering technique possesses excellent processing property, corrosion resistance and thermal stability, whose absorption rate and the emission ratio have reached the level of the German blue tape series. It can meet the domestic demand for high-level flat-plate market.

Abstract: A new kind of anti-oxidation coating for steel billets at high temperature was prepared. The resistance property of the coatings for oxidation was investigated. The result indicated that the coatings could decrease the oxidation loss at 1300¡æ. The anti-oxidation mechanism of the coatings on the surface of steel billets at high temperature was proposed at the same time.

Abstract: The composition dependence of crystal structure, lattice parameter, micromorphology, Curie temperatures, magnetocrystalline anisotropy constant of Tb_0.29Dy_0.48Ho_0.23(Fe_1-XMn_X)_1.95 (x0.3) alloys were investigated by the experiment. X-ray diffraction patterns demonstrate the Tb_0.29Dy_0.48Ho_0.23(Fe_1-XMn_X)_1.95 (x0.3) alloys possess MgCu₂-type cubic Laves structure. The lattice parameter of Tb_0.29Dy_0.48Ho_0.23(Fe_1-XMn_x)_1.95 alloy increases with increasing of x value. The Curie temperature T_c decreases from 375°C for x=0 to 316 °C for x=0.05, 265°C for x=0.1. The magnetocrystalline anisotropy constant K₁ of Tb_0.29Dy_0.48Ho_0.23(Fe1_-xMn_x)_1.95 (x0.3) decreases slightly with the increasing of x value. The magnetostriction was examined under applied magnetic field H in the room temperature. The Tb_0.29Dy_0.48Ho_0.23(Fe_1-xMn_x)_1.95 (x0.2) alloys have the character of giant magnetostrictive in room temperature. With the increasing of Mn concentration, the magnetostrictive of Tb_0.29Dy_0.48Ho_0.23(Fe_1-xMn_x)_1.95 (x0.2) alloy decreased.