Applied Mechanics and Materials Vols. 477-478

Abstract: The purpose of this study is the evaluation about the Micro-void generated by the impurity. The glass fiber reinforced composite made through the vacuum bag molding method was used with the impurity. The basalt fiber known as environment-friendly fiber was used as the fiber of the Micro-void specimen and the epoxy resin was used as the base material. The VaRTM process was performed for the making specimens. The change was given to the thickness of the impurity and pressure in order to see about production of the void. Consequently, as the thickness of the foreign material became thick and the pressure was enhanced, the size of the void grew and the production frequency of the void was enhanced.

Abstract: The present paper deals with the numerical evaluation of the effective Young's modulus values for the single-walled carbon nanotubes. The analysis is focused on the definition of the interatomic interactions applying the linear and non-linear numerical procedures and their influence on the results. The interatomic potentials, the continuum mechanics, and the finite element method are used in the conducted study. The non-linear numerical procedure revealed the variation of Young's modulus values for the carbon nanotubes during deformation.

Abstract: The aim of present study was to prepare the mononuclear microcapsules containing cinnamon oil (CO) using a complex coacervation method with gelatin and pectin as wall material. The surface morphology of microcapsule was characterized by optical microscopy and scanning electron microscopy (SEM). Then the microcapsules were analyzed by thermogravimetric analyzer (TGA) to confirm the cinnamon oil had been successfully embedded into the microcapsules and determine the loading capacity. The results showed that the microcapsules were uniform in size, spherical with a mean size of 13.6 ± 4.8μm. The microencapsulation yield, loading capacity and encapsulation efficiency were 65.4±3.3%, 43.3±1.3% and 42.4±1.7%, respectively.

Abstract: Nano inorganic particles, as a kind of rigid inorganic particles, can combine the characteristics of organic polymers and inorganic to obtain the composite materials with excellent comprehensive properties. In this thesis, nanosilica after surface modification was used as the modified agent, adding to polypropylene materials to get a series of polypropylene films with different content of nanosilica. Free volume characterizations of different polypropylene films were measured using the positron annihilation lifetime spectroscopy technique, and the residual solvents values were measured. Researches show that the free volume of polypropylene films changes result from the changes of nanosilica content. With the free volume of polypropylene films decreases, the residual solvents values become lower.

Abstract: Nanometer Al₂O₃/3Y-TZP powders were prepared by coprecipitation process and the Al₂O₃/3Y-TZP ceramics were prepared by microwave sintering under relatively low temperature. The relative density, bending strength and fracture toughness of the Al₂O₃/3Y-TZP ceramic samples were studied. The results showed that the Al₂O₃/3Y-TZP powders exhibited fine and homogeneous near-spherical particles with the size of 40-60 nm. With increasing the sintering temperatures, all of the relative density, bending strength and fracture toughness of the ceramic samples increased firstly, reaching the maximum values of 99.1%, 1236 MPa and 10.89 MPa·m^1/2 at 1250 °C respectively, and then decreased.

Abstract: A new growth method of graphene directly on the bare dielectric substrates by CVD (Chemical Vapor Deposition) method with Ga-Ni flux as sacrificial layer is reported in this work. Ga-Ni flux acts as not only a container to store carbon atoms which are dissolved from amourphous carbon film when heated, but also as a catalyst to promote the formation of graphene when cooled. In the process of growth, the Ga-Ni flux dewets and evaporates during the rearrangement of carbon atoms, resulting in graphene synthesized directly on the bare dielectric substrates. Scanning Raman Mapping and Spectroscopy, Scanning Electron Microscopy, and Atomic Force Microscopy were adopted to characterize the graphene film.

Abstract: Silver nanoparticles with narrow distribution were prepared by a simple route in water in presence of lauric acid as the capping agents. The morphology and crystal structure of as-synthesized silver nanoparticles were analyzed by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). The mass ratio of lauric acid and silver nitrate, the reaction temperature play important roles on the morphology and size of the silver nanoparticles. Well-dispersed silver nanopartilces with diameter of 8 nm were obtained when the mass ratio of lauric acid and silver nitrate was 1.2:1 and the reaction temperature was room temperature. It is also confirmed that the sol system was monodisperse nanosilver sol.

Abstract: Many important heavy forgings used in petroleum machinery field are made of SAE4330 steel. However, the mechanical properties of SAE4330 steel are greatly affected by its microstructures. In this paper, the eliminating methods of grain inheritance and grain boundary inheritance of SAE4330 steel are investigated. The microstructures, tensile properties and impact toughness of SAE4330 steel have been examined. The results show that the grain boundary inheritance is more seriously than the grain inheritance of SAE4330 steel. By using an appropriate heat treatment, the austenite size can be refined from grade zone to grade six. And the Austenite grain boundary inheritance can be removed completely by large deformation and heat treatment. There are three important steps should be strictly controlled for eliminating the mixed structure and coarse-grain of SAE4330 steel.

Abstract: Amorphous Fe₇₉Ti₁₆P₅ alloy powders were synthesized from commercially available elemental powders by mechanical alloying. The microstructure, thermal stability and crystallization kinetic of as-milled powders were analyzed by XRD, SEM and DSC. Moreover, bulk ultrafine-grained materials were fabricated through spark plasma sintering of the amorphous powders. Results show that the amorphous powders exists two exothermal peaks during crystallization process. The effective activation energies for crystallization are obtained 109.14 kJ/mol and 205.97 kJ/mol for E_p1 and E_p2, respectively, by using the Kissinger method. The mechanical properties of the bulk materials are remarkably improved with the increase in the sintering temperatures. The ultimate compressive strength increases from 1282 MPa to 2015 MPa, but absence of ductility.

Abstract: Ni-Ti alloys have been given a lot of attention, mainly for their innovative use in practical medical applications. These motives led to understand deformation mechanisms, particularly behaviors under fatigue loading. In this research, fatigue life will be investigated for different composition Ni-Ti alloy samples. Three different compositions were investigated under different fatigue loading; Ni52.8Ti47.2, Ni50Ti50 and Ni47.2Ti52.8. These samples were prepared three different techniques, casting, powder-casting and powder-metallurgical techniques. Nondestructive methods have been used to assist revealing further detailed effects of loading on Ni-Ti alloy structure. Ni52.8Ti47.2 has been found to have the best fatigue properties among other compositions.