Advanced Materials Research Vols. 562-564

Abstract: This paper predicts the effect of main parameters to the failure behavior of T300/AG80 composite plate under preload and laser irradiation by experimental testing and data fitting. The load holding device was used to give certain preload to composite plate specimens, and an Nd: YAG laser was used to give laser radiation simultaneously for testing the failure time of the specimens. By varying the magnitudes of preload and the laser power densities, the effect of preload and laser power density on the failure time is obtained. The reaction process was recorded with a high-speed camera. The experimental data were fitted to obtain the expression of the materials failure time with preload and laser power density. When the preload kept constant, the relationship between the failure time and laser power density was exponential function. When the laser power density kept constant, the relationship between the failure time and pre-tensile-loads was approximating linear, and pre-compress-load was quadratic. Fitting the empirical formula provides a reference to predict life for the composite structure applied both preload and the action of the laser irradiation.

Abstract: ZnO thin films were prepared on glass substrates by radio frequency co-reactive magnetron sputtering at different deposition time of 20, 40, 60 and 80 min. Surface morphologies and crystal structures were examined using atomic force microscopy and X-ray diffraction. As the deposition time increased to 60 min, surface morphologies of the films became smooth and distributed uniformly. The crystallinity along the c-axis improved as the deposition time increased. The photoluminescence (PL) studies indicate that three main emission peaks located at 439nm, 483nm and 525nm were observed. The intensity of 439nm emission increased to maximum as the deposition time was 80 min, while the intensity of green emission band (from 483 to 525nm) attained to maximum as the deposition time increased to 60 min.

Abstract: First the fretting wear behavior of CuS nanoparticles additives in grease were studied. The results show that the fretting wear volume reduce significantly when CuS nanoparticles additives add to grease. At the same time the existence of sulfid nanoparticles can reduce friction coefficient at the latter fretting time. The results of XPS tests show that Cu, Zn, Ni, S and B elements were founded in the film of wear scar. Secondly the effect of antiwear and oiliness additives on fretting wear behavior of nanoparticles additives in Grease were studied. It was found that when some antiwear, oiliness additives (such as T203, T322, stearyl alcohol or stearic acid) and sulfide nanoparticles were added to urea grease, a synergy effect between the two types of additives made fretting wear volume more small than that of either additive. Based on the results of contrast experiment and some analysis of fretting wear scars, we present the idea that two additives react with friction surface step by step. That is to say, the high chemical activity of CuS nanoparticles decompose first and form protective layer, the heat converted from chemical reaction of CuS decomposition and mechanical motion promote composition of common oil additives, thus protective layer is formed once again and wear volume further decrease.

Abstract: The inhibition effect of excellent environmental-friendly corrosion inhibitors-Vitamins B of hot dipping Zn coated steel in diluted HCl was investigated using quantum chemistry analysis and weight loss test. Calculation result shows Vitamins B have a number of active centers. The value of Mulliken charge, distribution of HOMO and LUMO implies its good ability of electron exchange with metal surface. The test results indicate IE% increased with the inhibitor concentration, and the highest IE reached 97%.

Abstract: To find out the important factors which decisively affect the soldering quality of photovoltaic modules, solar cells were soldered under different conditions (different temperatures, PbSn vs. SnAgCu solder, manual vs. semi-automatic). Experimental results show that the soldering quality of PbSn under 350°C in the semi-automatic soldering process was quite stable while the soldering quality of lead-free solder was generally unacceptable in the manual or semi-automatic process under different temperatures. This result indicates that the soldering process with lead-free solder still needs to be further improved. It was also found that most cracks were formed on the interface between the solder and the silver paste and then expanded outwards.

Abstract: The micromechanical model for predicting macroscopic effective elastic coefficients of aluminum honeycomb cores is established based on homogenization theory combined with FEM method. The effects of aluminum honeycomb cell geometrical parameters on the efficiency of materials are investigated based on the concept of material efficiency. By using MATLAB language, the material efficiencies of irregular orthotropic hexagonal aluminum honeycomb cores with various height-to-length ratio, thickness-to-length ratio and cell wall angle are simulated. The effects of cell geometrical parameters on the efficiency of material are obtained. The light-weight design for aluminum honeycomb core is analyzed in further. The results have guiding signification for the optimization design and engineering application of aluminum honeycomb core materials.

Abstract: After heat treatment at 800°C for 15min, a Cu-Al alloy was cryogenic treated at -196°C for 30min, the micro-mechanical properties of the Cu-Al alloy before and after cryogenic treatment were measured by nanometer mechanical testing system and the microstructure of the Cu-Al alloy were also analyzed by optical microscope, SEM/EDS and XRD. On the basis of that, the effects of cryogenic treatment on micro-mechanical properties of the Cu-Al alloy were investigated. The results show that the cryogenic treatment can refine the grains, and increase the hardness, elastic modulus, elastic recovery rate and ratio of hardness to modulus of the Cu-Al alloy. As a result, cryogenic treatment can improve the ability to resist applied load and anti-indentation creep effectively.

Abstract: The transformation temperature and time of α+γ₂ to ß in a Cu-Al alloy after cryogenic treatment during heating were measured by DSC, and the transformation activation energy of α+γ₂ to ß was also calculated. It is indicated that the Cu-Al alloy with heating rate of 10°C/min, the phase transformation onset and ending temperature is 561.75°C and 582.88°C, respectively, and the phase transformation time is126.6S. The phase transformation activation energy decreases with the increasing volume fraction of their phase transformation.

Abstract: In this study, 45 carbon steel was boronized and borosulphurized at 950°C for 2, 3， 4, 5, 6 and 8 h, respectively. The samples were characterized by scanning electron microscopy, optical microscope, microhardness tester and ring-on-block wear tester. It is found that the surface of borosulphurized samples was dense, compact and relatively smooth; Although the boride layers produced by boro- sulphurizing at 950°C showed a lower microhardness value compared with that produced by boronizing, the wear resistance of the borosulphurized carbon steel is higher than that of boronized sample due to formation of FeS phase in the boride layer.

Abstract: contourlet transform can extract image texture information more efficiently than wavelet transform and has been studied for image de-noising, enhancement, and retrieval situations, its low retrieval rate are still not satisfied due to feature extraction and other reasons. Focus on improving the retrieval rate of contourlet transform retrieval system, a new feature named variance distribution was proposed and a contourlet retrieval system was constructed in this paper. The feature vectors were constructed by cascading the energy and variance distribution of each sub-band coefficients and the similarity measure used here was Canberra distance. Experimental results show that using the new features can make a higher retrieval rate than the combination of standard deviation and energy which is most commonly used today under the same retrieval time and hardware complexity.