Materials Science Forum Vol. 1034

Abstract: The present investigation considers an experimental study of wear analysis of Al-6061 HMMC with SiC_p & Graphite_p as a reinforcement & optimization of wear testing parameters based on the Taguchi technique coupled with Linear Regression analysis. A Linear Regression Equation obtained from regression analysis is used as a confirmation test, for the optimum testing parameters that are obtained to get the minimum wear rate and maximum Co-efficient of Friction of Al-6061 HMMC. The wear rate experiments are carried out by utilizing the combinations of tribological testing parameters based on the L9 Taguchi OA with four testing parameters of namely applied load, Speed, Track diameter and % of reinforcement. The three materials, Al-6061 HMMC are developed by reinforcing Al-6061 aluminium alloy with different (3, 5 & 7) % of weight fraction (SiC_p+Graphite_p), particulates of size (<30𝜇m) in an electric crucible melting furnace. It is observed that sliding velocity has a significant contribution in controlling the friction and wear behaviour of Al-6061 HMMC (SiC_p+Graphite_p). A confirmation test is carried out to verify the results obtained through the optimization technique. In addition to above tests, Scanning Electron Microscopy (SEM) analysis, Elemental Characterization can be achieved by using of EDAX (Energy Dispersive X-ray Spectroscope), Surface Roughness is performed on the specimens to study the uniform dispersion of particulate matter, along with hardness test.

Abstract: Binary and ternary blends of poly lactic acid (PLA), acrylonitrile-butadiene-styrene (ABS) and tapioca cassava starch (TCS) were prepared by the help of melt blend method. Rheological and mechanical properties of the prepared blends were studied. Rheological properties were studied using capillary Rheometer, shear rate, shear stress, the non-Newtonian index, were determined .Mechanical properties were studied in terms of tensile properties, stress at break, strain at break and Young's modulus have been determined by help of Universal Test Machine (UTM-3969).The results shows the ternary blends reveals shear-thinning behavior, over the range of the studied shear rates where the true shear rate of the blend decreases while increasing the shear rate. It also found that the true viscosity of the blend decreases with increased ABS content.

Abstract: Na_0.5K_0.5NbO₃ (KNN) thin films were fabricated on (100) oriented SrTiO₃ substrates by spin coating a stable environmentally friendly aqueous KNN precursor. Homogeneous films with an average grain size down to 60 nm were observed after heat treatment at 900 °C. The high degree of texture was confirmed by XRD. The intensity of the KNN (100) reflection for films on (100) oriented substrates increased with increasing sintering temperature up to 900 °C. The ferroelastic and piezoelectric properties of the film was confirmed by PFM. Local piezoelectric properties of selected films will be discussed in relation to the processing conditions, microstructure and orientation of the substrate.

Abstract: In this study, doped ytterbium oxide (Yb₂O₃) nanoparticles (NPs) with different dopant type (Eu and / or Tb) and undoped were synthesized by wet chemical method using nitrate salt as a starting source. Afterwards, they were calcined at 900 °C for 4 h. The crystal structure phase, size, and morphology of undoped and doped Yb₂O₃ nanoparticles (NPs) were characterized by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Undoped and doped NPs were exhibited cubic bixbyite-type crystal structure (Ia-3 space group). Lattice parameter changes caused by dopant element in NPs were examined using X-ray peak profile analysis. In order to investigate the occuring changes in the crystal structure, average crystallite size (CS) and lattice parameter (LP) values were computed with Williamson–Hall (W–H) and Cohen-Wagner (C–W) methods, respectively. It was observed that the crystal structure of the doped NPs expanded compared to the undoped Yb₂O₃ NPs, which explains the increase in the LP and CS values. The LP values of all the NPs were ranged from 10.444 Å (R² = 94.9) to 10.453 Å (R² = 81.8) while the CS of them were between 19 nm (R² = 95.9) and 24 nm (R² = 88.8). All the NPs exhibited nearly spherical and agglomerate structure and there were also few pores between the agglomerate particles in the structure. Besides, continuous agglomerate morphology formation was observed in particles containing Tb. The average nanoparticle size values were varied between 46 and 115 nm depending on the dopant element.

Abstract: The unique metal to insulator transition (MIT) of vanadium dioxide (VO₂) makes it receiving extensive attention in the application of smart window. As for VO₂-based smart window, the critical transition temperature (T_c) is required to be reduced to near room temperature for practical applications. In this paper, we fabricated VO₂ films on ITO glass by hydrothermal method and applied voltage to ITO, therefore, the joule heat generated by ITO triggered the complete MIT of VO₂ at room temperature in very short time ~3 s with applied voltage of 12 V. The VO₂ film on ITO substrate shows obviously widened hysteresis behavior in the reversible transition process with a thermal hysteresis width of ~33 °C. The widened hysteresis loop makes it possible to stabilize the rutile phase (R) of VO₂ at room temperature via applying a low holding voltage of 6 V. The proposed VO₂/ITO film exhibits promising application in active smart window, and possesses advantages of simple structure, easy-fabricated and low-cost.

Abstract: To estimate the magnetic properties of the magnetic material, magnetic flux density waveform (B waveform) must be sinusoidal wave. However, it is necessary to control the exciting waveform in consideration of the distortion, because voltage waveform induced by B-coil is distorted due to the magnetic properties. As a result, the IBCM can make B waveform sinusoidal wave with the least number of feedbacks than any control method. Because the IBCM performs noise cancelling for measured waveform and make accurate exciting waveform from measured waveform.

Abstract: To estimate the magnetic properties with two-dimensional AC-magnetization with two-dimensional DC-biased magnetization, three different grades of non-oriented electrical steel sheets with two-dimensional DC-biased magnetization were prepared. As a result, in the high grade specimen, the difference in the magnetic properties depending on the excitation direction (AC excitation direction is parallel to DC excitation direction) was larger than in the low grade specimen, and the magnetic properties were the best when the excitation direction was the rolling direction. Non-oriented electrical steel sheets have small magnetic anisotropy. High grade non-oriented electrical steel sheets have a large magnetic anisotropy to compare with low grade non-oriented electrical steel sheets. It is thought that magnetic anisotropy increased in the high grade non-oriented electrical steel sheets because the B-H loops under DC-biased magnetization were minor loops. In addition, the increase rate of the H widths and the increase rate of the iron losses depending on the excitation direction were relatively consistent. Since the iron loss is proportional to the area of the B-H loop, it is considered that the iron loss increased at the same rate as the H width of the B-H loop.

Abstract: In the paper the change of the magnetic flux density under single harmonic distortion is discussed. Presented results show the dependence of the value of the magnetic flux density in the toroidal magnetic core made from the Ni80Fe20 tape of the phase angle of higher harmonic in relation to the main harmonic of distorted magnetizing current. Moreover, the influence of higher harmonic depends from it frequency and it becomes undetectable above 15th higher harmonic, even if its level reaches 50% of the RMS value of the main harmonic of distorted magnetizing current. Laboratory tests were carried out for the magnetic toroidal core of iCT with a current ratio equal to 300 A / 5 A. The oscilloscope is used to measure waveforms of the excitation current and the secondary voltage through the voltage probes. Build in numerical integration is used to determine the magnetic flux density from secondary voltage. In the case of tested 5^th higher harmonic the highest value of the magnetic flux density is obtained for phase angle equal to 90° between main and higher harmonics, while the lowest is obtained for 270°. This depends from the initial phase of the magnetic field strength and results from the integration of distorted secondary voltage with the particular content of higher harmonics.

Abstract: The research aimed to investigate the effect of calcium hydroxide content on pozzolanic reaction of calcined clays. Pozzolanic reaction of calcined clay was determined in terms of its mechanical properties, phase development and microstructures. Three clay minerals (two kaolinitic clays and kaolinite-montmorillonite clay) were chosen to produce pozzolanic materials via calcination at temperature of 700 °C to allow dehydroxylation of clay minerals. Ratios of calcium hydroxide to calcined clays were varied from 0.1 to 0.5. Mixing water contents or liquid to solid ratios (0.62, 0.75 and 0.80) and curing times (7 and 28 days) were also studied. It was found that calcium aluminosilicate hydrate (stratlingite) could be formed after pozzolanic reactions of all clay minerals. The development of stratlingite agreed with the strength development showing the highest compressive strength at 26 MPa (28 days) when kaolinite-montmorillonite clay was used as pozzolanic material and the ratio of calcium hydroxide to calcined clay was 0.5.

Abstract: The use of recycled materials to replace natural and artificial materials represents an interesting and real possibility for all industrial sectors to contribute to the reduction of the amount of waste disposed of and non-renewable resources consumed. This study reports the results of the measurements of the sound absorption coefficient carried out on specimens obtained from the recycling of different materials. A sustainable development of our planet requires us to adopt materials recycling policies to ensure the economical use of resources. Two types of materials have been studied: material obtained from the recycling of plastic bottles, and a material obtained from the recycling of asphalt milled. Both materials showed interesting sound absorption performances covering different frequency ranges.