Applied Mechanics and Materials Vols. 488-489

Abstract: Carbon nanotubes have unique physical and chemical, electrical, mechanical properties. As a new nanomaterial, it has great development potential. In this paper, the structure and properties of carbon nanotubes were briefly described, and the commonly used ways of preparation of carbon nanotubes were also introduced in detail. The importance of the development of new synthetic methods was put forward.

Abstract: At present steel industry is obtained a rapid development in China. More and more steel slag is accumulated. How to deal with steel slag becomes a hot problem. In this paper, the source, composition and characteristics of steel slag are introduced firstly. Then the methods of comprehensive utilization on the steel slag are summarized. Finally the problems are put up and the development trend of steel slag utilization is prospected according to the present situation of comprehensive utilization of steel slag.

Abstract: With the increase of Ti-bearing blast furnace slag, its harm is growing. It contains high titanium content. How to make good use of Ti-bearing blast furnace slag is currently a hot problem. In this paper, the conditions of comprehensive utilization on Ti-bearing blast furnace slag were described firstly. Then the features, application field and problems of extraction and non-extraction titanium from Ti-bearing blast furnace slag were introduced. The advantages, disadvantages and problems of comprehensive utilization of Ti-bearing blast furnace slag were analyzed. Finally the application prospects were forecasted.

Abstract: A series of alumina cores with different content of yttria were prepared by sintered at 1450°C. The flexural strength at room temperature, high temperature deformation and shrinkage rate of alumina based ceramic core were determined. the phase evolution and microstructure were studied by scanning electron microscopy (SEM) ,X-ray diffraction (XRD).The optimal yttria content on the combined properties of these cores were discussed. The results explained that The Al₂O₃ particles reacted with some Y₂O₃ particles to form a polycrystalline composition 3Y₂O₃·5Al₂O₃ (YAG), which activated the lattice and promoted sintering. Most of yttria, however, were concentrated in the ceramic grain boundaries, playing a role in improving grain refinement and microstructure; the cores achieved the best comprehensive performance when the content of yttria was 10%.

Abstract: Eight volatile organic compounds (VOCs) in melon seeds printing and packaging materials have been analyzed by a headspace gas chromatography and mass spectrometry method. The results of external standard method show that PET and aluminum foil as raw materials of melon seeds plastic bags contain less VOCs, but PE contains much more VOCs. There are more VOCs in printing inks. Red ink has the most amount of VOCs (2777.27 mg/kg). The binder contains 143.574 mg/kg of VOCs. PE and printing inks may be the main sources of VOCs in the melon seeds plastic bags. Residues of benzenes in the front plastic bag materials exceed national standards. The amount of VOCs and benzenes in the back plastic bag materials all exceed national standards.

Abstract: By the scanning electron microscopy, the microstructure and mechanical properties testing, the effect of Ca and Y on the microstructure and mechanical properties of magnesium alloy AZ81 are investigated in this paper. The results show that with Ca and Y addition, the grain size is refined. And with the β-Mg₁₇Al₁₂ phase reducing significantly, there will be the precipitation of Al₂Ca and Al₂Y. Meanwhile, the mechanical properties of AZ81 magnesium alloy are enhanced at room temperature and 150°C.

Abstract: The microstructure and mechanical properties of Mg-12Gd-2Y-0.5Zr alloy have been studied. The results showed that the alloy mainly consists of α-Mg matrix, Mg₅Gd and Mg₂₄Y₅. With the increase of temperature, the tensile strength of the alloy first increases and then decreases, and the peak value appears at 250°C. The elongation increases as the temperature increases.

Abstract: For 50SiMnVB steel shell formed fragments, AUTODYN-3D finite element software was applied to numerical simulate the process of fragment forming. The change law of velocity distribution of 50SiMnVB steel shell formed fragments under high energy explosive charge along the warhead axial was obtained. And the maximum velocity and penetration ability of 50SiMnVB steel shell formed fragments was researched by experiment. The result shows that, the whole process of shell breaking is about 70μs, and the velocity of shell expanding during it can be distributed to three phases called librating, accelerating and stability. The minimum initial velocity of fragments appears at where approaching detonation point, and its quantity is about 931.7m/s; The maximum initial velocity appears at where away from detonation point about 60% cylinder length, and its quantity is about 1488.3m/s. When fragment group penetrates 5mm thickness armor steel target with 1215m/s, its penetration probability is about 46.2%.

Abstract: Y and Gd are vital alloying elements to the AZ magnesium alloys. It is due to their functions mainly on solid solution strengthening and age strengthening. This paper reviews effect of Y, Gd on mechanical properties of AZ-series magnesium alloys. The future development direction is pointed.

Abstract: Epitaxial (Lu,Bi)₃(Fe,Ga)₅O₁₂ films were grown on GGG (111) orientated and GGG(100) orientated substrates by the LPE method over a wide temperature range. Epitaxial growth, surface morphology, chemical composition as well as magneto-optical properties of the films were investigated by ESEM, TEM, AFM, EDAX, and polarization optical microscopy. The magnetic anisotropy of the films, lattice mismatch as well as Bi concentration in the films is also discussed. The films exhibit in-plane or out-of-plane magnetization, depending on growth temperatures. The Bi concentration in the grown films and saturation magnetization field also exhibit a dependence on growth temperatures. When the film is very thin, its coercivity will increase and the orientation of magnetization transits from out-of-plane to in-plane.