Key Engineering Materials Vols. 531-532

Abstract: (0.996-x) K0.5Na0.5NbO3- 0.004 BiFeO3- x LiSbO3 (x =0.00, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07) lead-free piezoelectric ceramics were prepared by the conventional mixed oxide method. The compositional dependence of the phase structure and the electrical properties of the ceramics were studied. A morphotropic phase boundary between the orthorhombic and tetragonal phases was identified in the composition range of 0.03 < x < 0.06. With the content of LS increases, the size of the pores significantly decreases. However, adding larger amount of LS makes the pore size increase slightly. The (0.996-x)KNN-0.004 BF-xLS(x=0.05) ceramics possess good electrical properties: d33 = 280 pC/N, kp = 53.3%, Tc = 345 °C, εr = 1613, Tan δ =2.07%. These results show that the ceramic is a promising lead-free piezoelectric material.

Abstract: The crystal structure of aramid fibers is highly orientated. The structure of aramid fibers with various manufacturing processes and aramid paper sheets were analyzed and observed by using polarized light microscope (PLM). The change and its law of aramid fiber crystal structure in such processes as aramid fiber mamufaturing of aramid fiber/fibrids, forming of aramid paper sheets, and heat treatment were analysed. The relationship between the structural feature of aramid fibers and the performance of aramid paper was also discussed.

Abstract: Polycarboxylate-type superplasticizers with different side chains and approximative degree of polymerization are synthesized. The microstructures of Polycarboxylate-type superplasticizers in water are studied by fluorescent probe technique, dynamic light scattering (DLS), transmission electron microscopy (TEM) and the self-assembly technique. The results indicate that the formation of hydrophobic microenvironment in PC solution is confirmed. The higher the ratio of long side chains of PC, the stronger the hydrophobic microenvironment formed in PC solution. The Z-Average diameters of aggregation formed in PC solution increase with the increasing of long side chains content. In addition, the size and shape of aggregation is not of uniform distribution, and the reason for this is that association interaction of hydrogen bonding occurs among PC molecules or in the interior of single PC molecule.

Abstract: The polycrystalline Ti/TiN multilayer films were deposited by magnetron sputtering. We investigated the effects of mixed discharge gas pressure, bias voltage and substrate temperature on the microstructural, interfacial, and mechanical properties of the polycrystalline Ti/TiN multilayer films. X-ray reflectivity and diffraction (XRR and XRD), and nanoindentation were used to characterize the structures and mechanical properties for the films.The period of multilayer, interface width and grain size decrease with increaseing of deposition pressure. The multilayer coating at floating voltage shows TiN (111), Ti2N (103), and TiN (200) preferred crystalline orientation, whlie those at other different substrate biases show only TiN (111) and Ti2N (103) preferred crystalline orientation. It was found that the hardness increased with increasing substrate temperature. This hardness enhancement was probably caused by the modulus difference in the interface between layer Ti and TiN or the preferred crystalline orientation TiN(111).

Abstract: Nano-porous bilayers structure antireflection films on glass substrate were prepared by sol-gel method, tetraethyl orthosilicate(TEOS) and tetrabutyl titanate(TEOT) as the main raw materials, cetyl trimethyl ammonium bromide(CTAB) and polyethylene glycol(PEG) as template. The relation of the template agent addition, pH, and aging time to surface morphology and optical properties were analyzed. When the CTAB/TEOS = 1/30, the average spectral transmittance in the visible wavelength is 93.69% and the peak transmission is up to 97.37%. All the bilayers antireflection films are amorphous structure, uniform surface morphology, dense nano-porous size distribution, pore size is about 10nm.

Abstract: Compared with the local algorithm in stereo matching, the high quality disparity space image is calculated by the global algorithm, which is difficult to use in practical application for its long computation time. The dynamic programming is one of the global algorithms with a fast matching speed, but it has strip blemish in matching result. In this paper, a new dynamic programming based method is proposed to accelerate the matching speed and improve the matching quality. Firstly, the color feature of two images are calculated using the Laplacians of Gaussian pyramid algorithm, and the color feature of the image pair obtained are matched. Secondly, the matching points are taken as the ground control points of the scan line, which is cut into several short line segments. Finally, all line segments are matched to obtain the disparity of the scan line. The experimental results show that the matching speed is accelerated greatly with improved disparity image quality

Abstract: In the paper a detailed analysis of dynamic responses of a reinforced concrete bridge with steel-laminated elastomeric bearings to high-energy mining tremors registered in two main regions of mining activity in Poland (i.e. Upper Silesian Coal Basin and Legnica-Glogow Copper District) was presented. The representative time histories of accelerations from both regions were used as ground motion data in calculations of the dynamic response of the structure. The two-coefficient Mooney-Rivlin model was used as a constitutive model for hyperelastic non-linear elastomeric material. It was proved that the dynamic response of the bridge was strongly dependent not only on the level of vibration amplitudes but on the dominant frequency range of the mining shock typical for the mining region as well. Also the height of elastomeric bearings occurred to have considerable influence on the total dynamic response of the bridge. Two heights of bearings were analyzed: 42 mm and 85 mm. The increase of the height of bearings caused the decrease up to 25 % in the maximal principal stresses obtained in the dynamic analysis. The behaviour of elastomeric material in case of bearings 42 mm high occurred to be strongly non-linear, whereas in case of bearings 85 mm high behaviour of elastomeric material remained almost linear.

Abstract: In order to understand the fire safety of the various types of buildings, we need more flexible and efficient performance-estimating methods to verify fire protection safety in various types of buildings. Assuming can utilize computer fire simulation software CFAST / FDS + Evac to analyze Taiwan's domestic fire cases, in order to understand in the different fires heat flow transfer, and toxic smoke diffuse, and human evacuation to escape, and other important fire parameter characteristics, in the building the fire protection safety evaluating to produce the efficiency. This study is used cases of fires in four-story old-style residential and commercial mixed-use buildings to explain building fire performance-based numerical evaluation methods, and to provide quantitative data and reference information in Taiwan performance-based codes creating and the fire protection to project design is helpful in the buildings.

Abstract: As a key component of vehicle, automotive clutch remained high failure rate, meanwhile, with the development of engine and vehicle technology, functional characteristics of automotive clutch such as comfort, durability and reliability demanded much higher. Objective of the study is to establish the correspondence relationship between failures and design theory and experimental methods, reduce failure rate and improve product reliability. In order to create a system approach of problem-solving, we collected clutch failure information and classified according to clutch functional requirements and mechanical design principles. Then we used RCA (root cause analysis) and quality management tools to analyze the cause of failures, used QFD (quality function development) and DFMEA (design failure mode effects analysis) method to protocol the corresponding control measures to improve the existing design theory and experimental methods. The study also can be applied to more complex systems such as dry dual clutch module and dual-mass flywheel damper.

Abstract: Kinetic models can have practical applications for the optimization of the process and performance analysis, or economic estimations, so investigate the bamboo fiber kinetics is necessary. In this paper, effects of temperature and time on bamboo fiber hydrolysis in saturated formic acid with 4% hydrochloric acid solution reaction kinetics have been investigated. The rate constants, average apparent activation energy and frequency factors were evaluated according to the Arrhenius equation. The results showed that the hydrolysis velocities of bamboo fiber were 1.63×10-2 h-1 at 55 °C, 2.59×10-2 h-1 at 60 °C, 4.56×10-2 h-1 at 65 °C, 6.75×10-2 h-1 at 70 °C and 0.10 h-1 at 75 °C in formic acid solution with 4 % hydrochloric acid. The degradation velocities of glucose were 6.57×10-3 h-1 at 55 °C, 1.98×10-2 h-1 at 60 °C, 2.53×10-2 h-1 at 65 °C, 7.47×10-2 h-1 at 70 °C and 0.14 h-1 at 75 °C. The pre-exponential factor of Arrhenius equation of bamboo fiber hydrolysis reaction and glucose decomposition was 1.48×1014 h-1 and 2.32×1020 h-1 respectively. The activation energy of bamboo fiber hydrolysis was 87.65kJ/mol, and the activation energy of glucose degradation was 141.44kJ/mol.