Advanced Materials Research Vols. 875-877

Abstract: In this paper, the experimental investigation of polyurethane (PU) foam-filled into circular aluminum tubes subjected to axial crushing was presented. The purpose of this study is to improve the energy absorption of aluminium tube under axial quasi-static load. The aluminium tube was made from the AA6063-T5 aluminium alloy tubes. Each tube was filled with polyurethane foam. The density of foam was varied from 100, 150 and 200 kg/mP^3P including with empty tube. The range of diameter/thickness (D/t) ratio of tube was varied from 15-55. The specimen were tested by quasi-static axial load with crush speed of 50 mm/min using the 2,000 kN universal testing machine. The load-displacement curves while testing were recorded for calculation. The mode of collapse of each specimen was analyzed concerning on foam density and the influence of D/t ratio. The results revealed that the tube with foam-filled provided significantly increment of the energy absorption than that of the empty tube. While the density of foam and D/t ratios increase, the tendency of collapse mode is transformed from asymmetric mode to concertina mode.

Abstract: The paper presents some results about changes in integrity state of metal surface processed at different roughness levels subjected to fatigue plane bending tests. Experimental tests show that during fatigue process there are micro-geometrical changes related to local plastic deformations which can be evidenced by micro-hardness modifications and indentation size effect, ISE. ISE can be a quantitatively and qualitatively factor for characterize fatigue behavior of a metallic surface.

Abstract: Weld corrosion is suspected to contribute to localized corrosion failure of pipelines in CO₂ environment. Some studies on the mitigation of the weld corrosion had been focused on weld metal micro-alloying producing cathodic weld metal but with mixed success result. The inconsistent result is due to lack of understanding on the mechanism of weld corrosion in this corrosive CO₂ environment. This paper presents the study of the possibility of weld corrosion from the galvanic and self-corrosion effects of welded low carbon steel ASTM 106 B pipeline in pH 5-CO₂ saturated environment at 25 °C and 60 °C under stagnant condition. The weld region samples were prepared by metallography method to identify the parent metal (PM), heat affected zone (HAZ) and weld metal (WM) microstructures. Galvanic current was measured for each weld region by zero resistance ammeters (ZRA) and self-corrosion rate was measured by electrochemical impedance spectroscopy (EIS). The total corrosion rate was determined from the summation of galvanic corrosion and self-corrosion for all weld regions. From the galvanic current test result, weld metal was found to be anodic for both 25 °C and 60 °C. Weld metal also experienced the highest self-corrosion rate in the range of 40-98% as compared to parent metal and HAZ region for both 25 °C and 60°C. The total corrosion rate was mainly contributed by the self-corrosion rates and the contribution from galvanic corrosion was considered insignificant. Possible preferential weld corrosion can occur on weld metal region due to differential self-corrosion rates of each weld regions.

Abstract: In this paper we use electrochemical deposition to grow a layer of gray compact film on the steel, characterized the product by X-ray diffraction (XRD) we find the ZnO cone-like rods and hierarchical rod-like nanostructure are all preferentially growing along the C-axis, which is confirmed by the direction of crystal growth in the transmission electron microscope (TEM) image. In the TEM image we find the hierarchical ZnO nanorods have an in situ growth in the high-energy electron beam irradiation, which makes the specific surface area increase and to some extent enhance the absorption of light energy.

Abstract: This paper presents the analysis of new results of experimental investigating of the structure-phase compositions and mechanical properties of Ni-Cr-Al-based alloy after strong deformation and low temperature aging. We empirically established the isolation of new phase at long aging at 673 K in the result of complex reaction of recrystallization and cellular precipitation. The analysis of kinetic dependence of mechanical properties testifies to strengthening influence of a new phase.

Abstract: In this paper, various ZnO nanostructures, such as rods, flowers were grown on indium-tin-oxide (ITO) substrates by hydrothermal growth at low temperature, using the different concentrations of equimolar (1:1) zinc nitrate (Zn (NO₃)₂6H₂O) and methenamine (C₆H₁₂N₄) mixed as precursors solution, and adding ammonia solution to control the pH levels. SEM, XRD were utilized to characterize morphologies and crystal structures of ZnO. It was indicated that the concentration of precursor solution leads to the significantly changes in the nanostructured ZnO. The possible growth mechanism is discussed in this work.

Abstract: The spectral characteristic of the fluorescence film used in dissolved oxygen sensor is influenced by temperature. In this paper, we quantitatively studied the temperature effect of the dissolved oxygen sensitive film based on Ru (bpy)₃²⁺ complexes. In order to study how it was affected, two experiments were designed. One experiment was carried out when the sensitive membrane was dipped into solution of saturated sodium sulfite, in which case, there was no oxygen interference. The other experiment was implemented when the sensitive film was exposed to air, while the influence of oxygen was constant. In the processes of both experiments, we adjusted the temperature around the sensitive membrane. When the temperature rising from 0°C to 45°C, the fluorescence intensity emitted from the sensitive film was reduced which in the first experiment decreased from 5030counts to 3845counts and in the second experiment from 2314counts to 1407counts. Then a method can correct the temperature effect was proposed. The curve of spectrum at 25°C was supposed to be the standard and spectrums at other temperatures was corrected to be consistent with it. The correction coefficient of every wavelength was got through our calculation. After multiplying the coefficients, fluorescence intensity at different temperatures was approximately equal and the differences caused by temperature were eliminated.

Abstract: Nondestructive test systems are increasingly applied in the industrial context for their strong potentialities in improving and standardizing quality control. Especially in the service stage of rail, early detection of nucleus defects in the rail can avoid the broken rail accident. The aim of present work is to propose a kind of non-contact nondestructive testing method based on the laser and electro-magnetic acoustic transducer techniques, which is suitable to inspect the nucleus defects. This paper describes the testing system, principle and signal processing. The result shows the relative error of testing nucleus defects is about 3.24 %.

Abstract: The deformational properties and fatigue of asphalt layers are important for the design and assessment of semi-rigid and flexible pavements. The Two-point Bending Test was used for determination of deformational characteristics of asphalt mixtures on Department of Construction Management in Zilina. The results are evaluated with the KATEMS assessment software. The long-term research lead to estimation of deformational characteristics and fatigue of different types of asphalt mixtures. The tests have shown a positive impact of additives (ground rubber, hydrate lime component) on the results of these mixtures. This article is focused on assessment of deformational properties and fatigue of selected types of asphalt mixtures.

Abstract: Lead-free piezoelectric (Bi_1/2Na_1/2)TiO₃ (BNT) films were deposited on 0.2 mm thick pure titanium (Ti) substrates by a hydrothermal method. Scratch tests were performed to quantitatively assess the adhesion strength between BNT films and Ti substrates. Ti substrates were pretreated by chemical polish and mechanical polish respectively prior to BNT film deposition with a view of investigating the effects of substrate surface pretreatments on the adhesion of BNT film. In the scratch test, the behaviour of BNT film exfoliation was investigated by SEM observation. The scratch test results revealed that the chemical polish pretreatment effectively improved the adhesion of BNT films.