Advanced Materials Research Vols. 284-286

Abstract: A pressure-less infiltration technique was introduced to fabricate WC particles reinforced steel matrix composites through rapidly melting matrix by local electromagnetism induction heating. The four specimens were attained by adjusting the moving speed of sand mould and comparatively investigated. The results showed that the thickness of composite layer was about 4.0 mm. While the moving speed of sand mould was 3.0 cm/min, the reinforced particles had the better homogeneous distribution into the matrix and the metallurgical bonding with the matrix. The wear amount of composites firstly decreased up to a lower value and then increased. Except the sample produced under the speed 1.0 cm/min, the wear-resistant behavior of other three samples were superior to that of high chromium cast iron.

Abstract: This paper proposed a preprocessing method of SWCNTs dispersion based on rinsing technology. With the assistance of SDS, SC and SDBS, this method adopted the ultrasonication oscillation technology to solve the problem of SWCNTs dispersion. In addition, it compared the effect of the three kinds of surfactants on SWCNTs dispersion under the same conditions. And AFM was applied in this experiment to scan and image the samples. The results showed that the solubility and adsorption efficiency of the surfactants had influence on the SWCNTs dispersion quality. Furthermore, the paper primarily and theoretically modeled and analyzed the experiment results from the aspect of the surfactants' hydrophilic and lipophilic structure.

Abstract: The sepiolite and CuFe₂O₄ were combined to prepare the sepiolite/CuFe₂O₄ composite. The magnetic composite was characterized by X-ray diffraction (XRD), transmission electronic microscopy (TEM) and vibration sample magnetometer (VSM) and N₂ adsorption isotherms. Adsorption characteristics of the composite were examined by using Cu²⁺ and methylene blue as adsorbates. The results show that CuFe₂O₄ particles adhere to the surface of sepiolite fiber to form the sepiolite/CuFe₂O₄ composite which show well characteristic of superparamagnetism and is effective for the removal of Cu²⁺ or methylene blue. When the mass ratios of sepiolite and CuFe₂O₄ is 7:3, the saturation and remanence magnetization are 7.140 and 0.0246 A·m²/kg, and coercive force is 0.0180 A/m for magnetic sepiolite. The saturated adsorption capacity for Cu²⁺ and the removal rate of methylene blue is 15.72 mg/g, 99.48%, respectively.

Abstract: The effect of added BN on the electro-magnetic properties and enhanced room temperature magnetoresistance in (1-x)La_0.7Ca_0.2Sr_0.1MnO₃ (LCSMO)+x(BN) composites has been studied systematically. The results of X-ray diffraction (XRD) and SEM show that BN and LCSMO coexist in the composites and BN mainly goes into the grain boundary region without any chemical reaction with LCSMO. The results of electronic measurements show that the intrinsic insulator-metal transition temperature (T_P) does not change, which is in accordance with the results for the Curie temperature T_C. It is interesting to note that an enhanced magnetoresisitance (MR) effect for the composites is found over a wide temperature range from low temperature to room temperature in an applied magnetic field of 3 kOe. These phenomena can be explained by considering that BN, which segregated at the grain boundaries or surfaces, does not change the intrinsic structure of LCSMO. We argue that the introduction of BN gives rise to magnetic disorder and hence an enhanced tunnelling effect, which is responsible for the MR enhancement.

Abstract: Organophilic Bentonite / Paraffin composite phase change energy storage materials (OB/P PCM composite) were prepared by melting intercalation method. Under high temperature, no melt paraffin seep out from the PCM of organophilic bentonite/paraffin (OB/P) mass ratio is 2:1, which paraffin content is largest. Samples were tested by X ray diffraction (XRD), Scanning Electron Microscope (SEM), Differential scanning calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR). Paraffin was well intercalated into layerd bentonite. Melting point and fussion heat of composite PCM with mass ratio2:1 are 45.7 °C and 68.7 kJ/kg, it can be added to solar energy.

Abstract: This paper discusses the response of balanced angle-ply graphite/epoxy composite laminates subjected to different strain rate compression loading using a compression split Hopkinson’s pressure bar (SHPB) and an MTS machine. Five types of laminates, with ply angles 0°, ±15°, ±45°, ±75°and 90°were manufactured using T700 carbon fiber with epoxy resin system by hand. Samples were subjected to compression loading at different strain rates along longitudinal direction. The stress-strain curves at different strain rates were compared for each sample type. Characteristics of the curves were summarized and the causes were analyzed. Finally, the relationship between failure strength and ply angles was analyzed.

Abstract: This paper analyzes the characteristics of bitmap and vector, introduce based on Photoshop, CorelDraw, Flash, Streamline and other software methods for bitmap conversion vector. Still introduce based on AutoCAD for vector conversion bitmap method.

Abstract: Regarding welding power-arc system stability (WPSS) as the research object, the paper uses differential theory and considers the full load conditions from the external circuit on the course of dynamic welding, and some models about WPSS are found, they can obtain the analytic expression of system stability coefficient, and a qualitative analysis of WPSS' conditions is so born, on this basis, by the method of the relative conversion of current deviation, a dynamic factor of current deviation (DFCD) is obtained by analytical equation，then to quantify stability of the system by the way of decay time of deviation. Test's results, based on analysis of voltage and current waveforms, are the same to quantify the WPSS based on DFCD.

Abstract: The sulfide capacity (C_S) and equilibrium distribution ratio of sulphur (L_S) are important indicators to measure desulfurization capacity of slag system. The sulfide capacities of CaO-SiO₂-MgO-Al₂O₃-Fe_tO slags are calculated by optical basicity model and KTH model, and compared with measured values in literature. The results show that the values calculated by KTH model are nearer to measured values than by optical basicity model, so the former can be used to predict C_S of different slag compositions. The factors affecting C_S are also studied in detail. The results show that C_S increases with increasing slag basicity and temperature and decreases with increasing MgO and Al₂O₃ contents in slag.

Abstract: Based on the tunnel effect, a mathematic model was set up to describe the tunnel resistivity of carbon black-filled cement-based composites (CBCC). The relationships between the tunnel resistivity and the microstructure parameters, the motion parameters of carriers as well as the external electric field strength in the CBCC were established by using the model. Furthermore, the inherent relation between the tunnel resistivity and carbon black volume fraction was discovered. Moreover, the effect of carbon black volume fraction on tunnel effect of CBCC was investigated through experiments. The theoretical results obtained from the model were in agreement with the experimental data, which proved the rationality of the tunnel resistivity model of CBCC.