Materials Science Forum Vol. 724

Abstract: The thermal decomposition characteristics of Mg (NO₃)₂·H₂O and MgCl₂·6H₂O composite were studied by integrated thermal analysis. Results show that there are five steps during the thermal decomposition of phase change material (PCM): the starting temperature of each step is 35.5°C, 93°C, 196°C, 260°C and 318°C, respectively. PCM was calcined at different temperatures at each decomposition step. The composition and morphology of the calcined product was characterized by XRD and SEM. Two major reactions including dehydration and hydrolysis occur in the thermal decomposition progress. Dehydration is the main process below 196 °C, while hydrolysis is predominant process when the temperature is higher than 196 °C.

Abstract: The SiC reinforced ferrous based armor composites were treated with three heat treatments of annealing, isothermal quenching and annealing. The relationships between the treatment processing and the microstructures and hardness of the composite material were investigated. The results revealed that the heat treatment had scarcely any influence on the reinforced component but there appeared iron silicide existing at the interface of the two component, and the hardness of the component changed in three same treatment situation, the highest hardness of the matrix reached 532HB after subjecting to the isothermal quenching at 300°C.

Abstract: The inspection of the TFT device for the LCD panel has been usually carried out by the large-scale electron column where the kinetic energy of the electron beam is higher than 10 kV, which has many disadvantages for the inspection. In this work, we replaced the bulky electron column with a tiny microcolumn and carried out the inspection of the TFT device. The result shows that the low-energy e-beam inspection can clearly observe the physical defects of the devices and also identify the abnormal electrical behavior caused by the defects in the device.

Abstract: Although the electron-beam (e-beam) inspection can find the non-visual defects in the semiconductor devices under the fabrication procedure, it has a problem of low inspection speed. To resolve this problem, in this work, we have demonstrate the low-energy e-beam inspection using a tiny microcolumn as the e-beam source. The experimental result indicates that the non-visual defects in the wafer can be easily identified by measuring the e-beam current at the backside of the wafer. Since it is not difficult to make the multiple e-beam sources by packing many microcolumns, we can enhance the inspection many times by using the microcolumn e-beam sources.

Abstract: Al₂O₃/TiAl composites doped with Cr and V₂O₅ were successfully prepared from Ti, Al, TiO₂, Cr and V₂O₅ by in situ hot-pressing. The synthesis process and the microstructures of as-fabricated samples were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the reaction process could be divided into three stages: firstly, Ti reacted with Al to form TiAl₃, then TiO₂ and V₂O₅ were reduced by Al to form Al₂O₃, and finally TiAl and Ti₃Al occur from the competitive solid-state diffusion reactions. The as-synthesized composites mainly consist of V and Cr doped matrix phases of γ-TiAl and α₂-Ti₃Al and dispersive Al₂O₃ phase. The in situ formed fine Al₂O₃ particles mainly disperse on the boundaries of TiAl. Compression strength shows a peak value of 1096.22 MPa at 7.54 at.% Al₂O₃ content.

Abstract: Recently the interest on rainwater harvesting has been increasing and the installation of rainwater harvesting system (RWHS) has been spread. However, little information is available about influences of catchment materials and system configurations on rainwater quality. This study was performed to examine the rainwater quality according to catchment conditions and system configurations in a roof RWHS. The catchment area of the building #39 in Seoul National University, Seoul, South Korea is 3,652 m² and consists of the concrete roof, roof garden and marble terrace. RWHS provides water for toilet flushing through the supply facilities. Water quality was analyzed at each catchment area and facilities of the system during rainfall. The pH, EC, turbidity and SS of runoff from the marble terrace showed higher than those of runoff from roof and roof garden. As influences of runoff from terrace and roof garden, turbidity, SS and EC showed high concentration in early part of the RWHS, but those were lower as passing through the system. Catchment conditions should be considered carefully in design of RWHS. Furthermore, the change of water quality due to the arrangement and configurations of the system should be reflected to evaluate water quality in RWHS.

Abstract: The artificial aggregates (AAs) were manufactured from the parent batch powders consisting of bottom ash produced at thermal power plant and dredged soil by direct sintering method at 1050~1200°C for 10min. The bloating phenomenon could be occurred in AAs due to a gas-capturing caused by large quantity of liquid formed at the specimen surface. Increasing the amount of the Na₂O added enlarged the area of black core and size of the macro pores in the aggregates. The inside black core got out of the surface of the specimens sintered at 1200°C showing the rugged and cracked surface, but this morphology did not cause a water absorption to increase.

Abstract: The relationship between the viscosity and the electrical conductivity of CaF₂-SiO₂- Al₂O₃-CaO-MgO slag system was deduced through theoretical calculation and experiment. The experiment was designed by quadratic orthogonal rotary regression method. The slag viscosity and conductivity were measured at 1600, and the constant (C) was calculated. The calculating model between each component mass fraction and constant C was performed, and the stability of calculating model was also verified by representative slag. The results showed that the calculating constant (C) of regression model is in good agreement with experimental values. Thus, the relationship between refining slag viscosity and conductivity using the formula at certain temperature is feasible.

Abstract: Fracture failure behavior of the electric resistance welding (ERW) seam weld of Φ355.6×10.3 mm L360 in high internal pressure was investigated in this paper. The mechanical, metallurgical and fractographic characteristics were studied to clarify the reason of fracture failure for the ERW seam weld. The experimental results showed that the impurity and flaw of weld area were the main factors for the failure of ERW seam weld in high internal pressure. The impurity and flaw in welds had great effects on the mechanical characteristics of ERW. The approaches to ensure the integrity of the pipeline in service were proposed.

Abstract: The reaction in linear low density polyethylene/Calcium carbonate (LLDPE/CaCO₃) melting blend system with the presence of fatty acid extracted from Hogwash oil (HWOFA) was investigated by means of a Torque Rheometer during compounding. The characteristics of the products were evaluated by DSC and Universal Testing machine. The results showed that the maximum torque and equilibrium torque of the LLDPE/CaCO₃ blends with addition of 15wt% HWOFA decreased respectively by 23.83% and 27.55% which were lower than that without HWOFA. The tensile strength decreased by 23.94%and the elongation at break increased by 16.88%. The compatibility became poor with addition of more than 15wt% HWOFA. The above results indicated that the fatty acid extracted from Hogwash oil can be used as a lower-cost plasticizer, which provides a new method of utilization of Hogwash oil.