Applied Mechanics and Materials Vols. 313-314

Abstract: A waterborne coating of waterborne acrylic resin based material was developed with different sizes of hybrid homemade graphite as conductive filler. Effects on its electrical conductivity and electromagnetic shielding performance were further analyzed and tested, such as conductive filler, coupling agent and iodine addition. The results showed that coating volume resistivity was about 0.05Ω·cm according to the optimal proportion, and attenuation of electromagnetic wave could reach more than 30dB within the frequency range of 1 MHz~1.5 GHz.

Abstract: The effect of medium-density current on the morphological stability of S/L interface of Pb-80wt%Sn alloy during directional solidification was investigated. The results indicated that both the DC of positive and negative 200 Acm^-2 could decrease the critical growth rate of cellular/dendrite transition and minish the range of growth rate of cellular crystal. DC accelerated the microstructure transition from cellular crystal to dendrite crystal at the same pulling rate. Furthermore, the dendrite crystal was refined by positive and negative DC at high pulling rate. The effect of direction of DC to the microstructure transition could be neglected. In conclusion, the positive and negative 200 Acm^-2 decreased the stability of solid/liquid interface of Pb-80%Sn alloy, and the lower the pulling rate was applied, the more obviously DC affected the microstructure.

Abstract: The potential distribution of carbon steel under epoxy coating exposed to natural seawater was investigated by the wire beam electrode (WBE) technique. The electrochemical impedance spectroscopy (EIS) of the WBE was characterized to analyze the behaviour of the coating degradation and metal corrosion at coating/metal interface. The mechanism of coating degradation was discussed from a point of electrochemical distribution. This research showed that the potential distribution had a close relationship with the characteristic of EIS in local area. The combined method can help us better understand the mechanism of the organic coating degradation and beneath substrate corrosion.

Abstract: Nonepitaxially grown FePt (x)/FePt:C thin films were synthesized, where FePt (x) (x=2, 5, 8, 11, 14 nm) layers were served as underlayers and FePt:C layer was nanocomposite with thickness of 5 nm. The effect of FePt underlayer on the ordering, orientation and magnetic properties of FePt:C thin films has been investigated by adjusting FePt underlayer thicknesses from 2 nm to 14 nm. X-ray diffraction (XRD), together with transmission electron microscopy (TEM) confirmed that the desired L1₀ phase was formed and films were (001) textured with FePt underlayer thickness decreased less 5 nm. For 5 nm FePt:C nanocomposite thin film with 2 nm FePt underlayer, the coercivity was 8.2 KOe and the correlation length of FePt:C nanocomposite film was 67 nm. These results reveal that the better orientation and magnetic properties for FePt:C nanocomposite films can be tuned by decreasing FePt underlayer thickness.

Abstract: Resistivity oil-water interface imager ( well to ERT ) is applied to the remaining oil in mining, according to water and oil interfacial resistivity changes to determine the fracture trend, and for the remaining oil exploitation to provide technical supports. In order to realise long-term telluric recordings correctly, and through receive cable, NI acquisition card, and ultimately sent back to the receiver, and have good resistance matching to the next step of data processing. Electrodes is one of measuring some physical quantities to distinguish the ability to directly determine the accuracy and reliability of the inversion. The use of very stable electrodes is necessary.

Abstract: In order to study the influence of undercooling, crystallization time to Al₂O₃ nanoparticles. To design a set of nanofluids crystal test system, and study the process of base fluid and Al₂O₃ - H₂O nanofluids crystallization. Results show that the base fluid added nanoparticles, degree of undercooling significantly, with the increase of mass fraction of nanoparticles and fluid crystallization time is shortened. Nanofluids phase transition temperature increased by 0.5 °C than water, reduce the energy consumption of the refrigeration unit.

Abstract: The35kg ingot was refined with vacuum induction furnace by means of three various deoxidationprocesses in laboratory. From the steel-making point of view, effect of deoxidationprocess on inclusions and was analyzed. The fraction, size and distribution ofinclusions were studied with scanning electron microscope (SEM)and energy dispersive spectrometer (EDS) in three various deoxidation processessteel . The results showed that the volume fraction of inclusions was thelargest in Ti/Zr deoxidation process and the inclusions distributed uniformly. Itwas found that the amount of fine inclusions size in the range of 0.5~1.5 μmwas the largest atTi/Zr deoxidation process. The fraction of inclusions decreased with holdingtime increasing during alloying in present study.

Abstract: Temperature dependent current-voltage (I-V) and capacitance-voltage (C-V) measurements were utilized to understand the transport mechanism of Pd Schottky diodes fabricated on Zn- and O-faces of ZnO. From I-V measurements, in accordance with the thermionic emission mechanism theory, it was found that the series resistance R_s and the ideality factor n were strongly temperature dependent that decreased with increasing temperature for both the faces (Zn and O-face) of ZnO revealing that the thermionic emission is not the dominant process. The barrier height ø _B(I-V) increased with increasing temperature for both faces. The measured values of ideality factor, barrier height and series resistance for Zn- and O-faces at room temperature were 4.4, 0.60 eV, 217 Ω and 2.8, 0.49 eV, 251 Ω respectively. The capacitance-voltage (C–V) measurements were used to determine the doping concentration N_d , the built-in-potential V_bi, and the barrier height ø _B(C-V). The doping concentration was found to be decreased with increasing depth. The barrier height ø _B(C-V) calculated for O-polar and Zn-polar faces decreases with increasing temperature. The values of barrier height ø _B(C-V) determined from C-V measurements were found higher than the values of barrier height ø _B(I-V). Keeping in view the calculated values of ideality factor, barrier height, and series resistance shows that O-polar face is qualitatively better than Zn-polar face.

Abstract: In the process of use BP neural network to fault diagnosis of analog circuits, the network input which represents fault signature was very important. A given new method which base on multi-points and multi-feature information is taken to construct the original sample set. With this method to construct the original fault signature set, then as the input of BP neural network and train the network. Simulation results show that, the network train with sample set which constructed by this method use in fault diagnosis of analog circuits is better accuracy than traditional methods. Proved the feasibility of this method in fault diagnosis of analog circuits, and offer a new method for fault diagnosis of analog circuits.

Abstract: In the new era, the reliability technology based on physics of failure (PoF) is playing an increasingly important role in development of electronic equipment. PoF models of electronic products, as the foundation and core of this advanced technology, are the main point of engineering application. With continual scaling of VLSI in electronic equipment, the electric field across gate oxide becomes higher and higher and affects the reliability of semiconductor device greatly. In this paper, TDDB failure mechanism and Physics-of-Failure model was researched firstly. Then the test sample was designed and processed, and the test verification program for TDDB Physics-of-Failure model was carried out to develop the test verification, collect and process test data. Through analyzing test data, the parameters of TDDB model were determined and modified to ensure the Physics-of-Failure model precision and the model could be used in engineering. Based on modified model, the reliability of integrated circuits can be evaluated at designing stage. And the inherent reliability of integrated circuits in electronic equipment could be improved by design optimization to reduce the risk in the process of using.