Advanced Materials Research Vols. 129-131

Abstract: LiSn2P3O12 has been prepared using mechanochemical milling method and sintered at 700 °C, 800 °C, 900 °C and 1000 °C for 8 hours. All samples sintered up to 900 °C show a rhombohedral structure. However, the sample sintered at 1000 °C possessed a monoclinic structure. This is attributed to the rotation of skeleton LiSn2P3O12 as indicated by the change in the a and c parameters of the sample. The sample sintered at 700 °C shows the highest bulk conductivity of 1.65 × 10-6 S cm-1 and the lowest bulk activation energy of 0.09 eV. The grain boundary activation energy of the samples decreases with increase in sintering temperature due to enhancement in grain contacts.

Abstract: Bone loss and bone thickening phenomenon occurred due to different stiffness of the implant and femur. Implant with stiffer materials than the bone carries majority of the load and it transferred down along the implant till the distal tip of the stem. Both phenomenons contribute to stress shielding and loosening of the prosthesis stem. In this study, the stress distributions in intact femur and THR femur are established using finite element method. The THR femur model consists of cemented hip Ti6Al4V and CoCrMo prosthesis stem implanted inside the femur bone. Effects of different material properties of the prosthesis stem on the resulting stress distributions are investigated. Results shows that the largest discrepancy in stress values between intact and THR femur is predicted along the middle region at both lateral and medial planes. The distal region shows that the calculated stress for both THR femur experienced higher stress magnitude than that of intact femur. The higher stress in THR femur leads to bone thickening at the particular region. The corresponding stress magnitude saturates at 25 MPa for THR femur while intact femur is slightly lower at 22 MPa.

Abstract: Free cutting steel is energy save material gradually extensive applied in the development of the engineering industry, but it is one of the three steels hard to continuous casting. At high temperatures, the corrosion of refractories by free cutting steels is one of the reasons for free cutting steels hard to continuous cast with a long time. Through the observation of the used refractories microstructure and detail discussions, it is concluded that Al2O3 in alumina carbon materials for the continuous casting is easy to react with FeO or MnO in the steel to form the low-melting point material, which is the main reason for the corrosion of the refractories when used to cast free cutting steels. After decarburized layer is formed on the hot surface of the spinel-carbon material, low-melting point materials will infiltrate into the decarburized layer and separate the particles into an isolated state, which will result in the corrosion of the materials by the scour of the molten steel. Through the formation of composite bond in the spinel-carbon materials, the corrosion resistance to the free cutting steels can be further improved. Based on the corrosion mechanism, the suggestions for the functional refractories with high corrosion resistance to free cutting steels are also provided.

Abstract: Power transformer is one of the most important electric equipments in power network, its running state has a direct effect on its safe operation of power network. Fault’s occurrence of power transformer probably result in vast hazards or accidents. According to statistics, its over-temperature operation of winding often result in different fault patterns, such as aging, breakdown and its burnt, etc, which has a large proportion in its accidents of power transformer. In this paper, based on the thermal analysis theory, a 3D thermal field model of transformer’s winding and core is respectively established in ANSYS software environment. And its 3D temperature field distribution of power transformer, including winding and core is simulated. Numerical simulated results provide a reliable and convenient reference for its thermal performance analysis of power transformer.is simulated. Numerical simulated results provide a reliable and convenient reference for its thermal performance analysis of power transformer.

Abstract: The flow stress curves of Q345B microalloyed steel during hot compression deformation were obtained at 900-1100°C and strain rates of 0.01-10s-1 on Gleeble-3500 thermo-mechanical simulator. Based on the experimental results, a inverse regression analysis method was proposed to determine the mathematical model of dislocation density and its correlation coefficients using the flow stress curves, so as to laid the foundations for calculating carbonitrides precipitates, deformation resistance and the end-rolled strength of microalloyed steels during hot rolling precisely. The effects of the deformation parameters (strain rate and deformation temperature) and microstructural evolution (work-hardening, dynamic recovery and dynamic recrystallization) on dislocation density were taken into account. Finally, the validity of the proposed model is discussed considering the plausibility of the parameters assessed for evaluating the dislocation density. It was proved that the model was reasonable and it could provide a guide to production.

Abstract: In electrospinning, outlook of fibrous assembly changes not only with the variation of collecting setups, but with the electrospinning process. For example, formation of multiple jets on a single droplet at special electrospinning conditions can produce several regions of fibrous webs simultaneously, which is bound to bring a great increase of production of nanofibers. The initiation method of multiple jets during electrospinning was derived through an experimental investigation by means of a high-speed camera, which was used to obtain the information of the shape change of a droplet along with process conditions, such as solution concentration, voltage and flow rate. Results showed that multiple jets could be initiated in a controlled manner when droplets experienced several cycles of dripping at relatively high voltages and flow rates in a certain concentration range. An interesting phenomenon of the auto-initiation of double jets was further observed in our experiment.

Abstract: Winding molding is a commonly-used molding method for composite fiber materials. In this method, the fiber winding tension control is a key technique in fiber winding since the winding tension directly affects the quality of winded products. Here designed is a closed-loop tension control system, equipped with the PLC as the main controller, the industrial control computer as the upper-host, the alternating numeric servo-electromotor and air cylinder as the actuators, and with the angle sensor of real time feedback filament tension change is designed. Presented below is Fuzzy-PID control algorithm, which combines the advantages of PID and fuzzy control by adopting the theory of adapt fuzzy control in big error range and adapt PID control in small error range. Experimental results prove that the principle of the design scheme is right with tension deviation less than 4 pers, response time about 0.4s and thus meeting the requirements of the system well.

Abstract: The Dynamic Design Analysis Method (DDAM) calculation principles and procedures are addressed for a system with two degrees of freedom (DOF). The basis of the U.S. Navy DDAM design input spectrum is introduced. Shock response analysis by DDAM for a certain gas turbine foundation is conducted, followed by the displacement and stress response of key parts, such as the flexible supporter. Furthermore, weak positions of the foundation in shock environment are found. The shock isolation ability of metal-rubber originally used as the vibration isolator is also verified by comparison. Finally, design guidelines for the anti-shock optimization of the foundation are given.

Abstract: Shrinkage can be critical factor for the design of structural members due to the length changes by the time-dependent deformation. In this investigation, two self-consolidating concrete (SCC) and two high-performance concrete (HPC) mixtures with target 56-day compressive strengths of 55 and 69 MPa and having 18-hour release strengths of 34.5 MPa and 43 MPa, respectively, were used to cast four full-scale AASHTO-Type II girders measuring 9.44-m in length. For each strength level, the SCC and HPC mixtures were proportioned with the same water-to-cementitious materials ratio (w/cm) and binder type. The high-range water-reducing admixture (HRWRA) dosage was adjusted to obtain a slump flow of 680 ± 20 mm for the SCC mixtures and a slump of 160 ± 20 mm for the HPC mixtures. The constructability and shrinkage of full-scale girders cast with SCC and HPC mixtures used in precast prestressed girders were investigated and compared. Results of tests on full-scale girders indicated that, SCC placement was successfully carried out by casting the concrete from location at the midspan of the 9.44-m long girders. Both HPC and SCC mixtures developed similar autogenous shrinkage for the mixtures made with the similar w/cm; the two SCC mixtures developed about 20% greater drying shrinkage than the comparable HPC mixtures after 112 days of drying.

Abstract: Bamboo is so easily Mouldy that bamboo products have no high value added utilization. Therefore, the effect of red extractives from 18 plantation woods on bamboo biology moulding was studied based on full-factor test. The results were: (1) The red extractives of plantation could mostly inhibit the growth of Penicillium expansum, but a few could inhibit the growth of Aspergillus niger. (2) The red extractives of Cunninghamia lanceolata bark and shavings, Deodar cedar branch, Eucalyptus dunnii bark, Eucalyptus tereticornis bark, Bagasse, Eucalyptus camaldulensis branch and shaving were the most effective in controlling spore germination of Penicillium expansum, and the one raphiolepsis branch was the most effective in controlling spore germination of Aspergillus niger. (3) The effect of the red extractives from Cunninghamia lanceolata bark and shaving, Deodar cedar branch, cypress branch, Eucalyptus tereticornis branch on bamboo moulding was highly remarkable on outdoor test. So the plantation woods could be used as biologic mould inhibitor for bamboo.