Ciri Kekenyalan dan Kesan Rawatan Haba ke Atas Siri Kaca Plumbum Zink Fosfat

Fabrikasi sistem siri kaca binari zink fosfat (ZnO)x (P₂O₅)1-x, plumbum fosfat (PbO)x (P₂O₅)1-x, dan kaca sistem temari plumbum zink fosfat (PbO)x [(ZnO)y (P₂0₅) 1-y] 1 -x dengan peratusan mol x dari 0.3 hingga 0.5 telah dilakukan dengan kaedah lindapan leburan. Sifat fizikal seperti sifat kekenyalan ditentukan pada suhu bilik dengan kaedah tanpa musnah yang menggunakan teknik Pemprosesan Isyarat Berdigit, peralatan sistem Matec DSP MBS 8000. Ketumpatan kaca diukur dengan menggunakan prinsip Archimedes. Data-data halaju gelombang dan ketumpatan yang diperolehi digunakan untuk menentukan pemalar kekenyal, modulus Young, modulus pukal, nisbah Poisson dan suhu Debye bagi sistem siri kaca plumbum zink fosfat. Pemalar kenyal, modulus Young, modulus pukal dan nisbah Poison didapati meningkat dengan penambahan ZnO atau PbO dalam kaca fosfat. Penambahan plumbum oks ida dalam kaca zink fosfat juga dapat meningkatkan pemalar kenyal, modulus Young dan modulus pukal serta suhu Debye kaca yang dihasilkan. Proses rawatan haba melalui proses sepuhlindapan terhadap semua sampel kaca yang dikaji telah dijalankan pada julat suhu di antara 100°C hingga 250°C pada sela suhu 50°C. Faktor sepuhlindapan didapati menyebabkan sedikit perubahan ke atas pemalar kenyal, modulus Young dan modulus pukal kaca. Ciri-ciri kenyal kaca ini adalah berkait rap at dengan kekuatan struktur kaca

Influence of sintering temperature on the structural, magnetic and dielectric properties of Ni0.8Zn0.2Fe2O4 synthesized by co-precipitation route.

The polycrystalline Ni–Zn ferrite powder with the chemical formula Ni0.8Zn0.2Fe2O4 has been synthesized using co-precipitation route. The toroidal and pellet form samples were sintered at various temperatures from 700 to 1300 °C/5 h in steps of 200 °C. The structures of samples were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and the energy dispersive X-ray spectroscopy (EDXS). The magnetic and dielectric measurements were carried out using a vibrating sample magnetometer (VSM) and the impedance analyzer, respectively. The highest density of 4.48 g cm−3 was obtained for the sample sintered at 1300 °C. It was found that the initial permeability increased from 4 to 17 and the RLF was in the order of 10−3 to 10−4 in the frequency range of 1.0 MHz to 1.0 GHz. The dielectric constant and dielectric loss were lower compared to the reported values for conventional solid state technique. The electrical resistivity is in the order of 108 Ω cm. Therefore, low relative loss factor and high resistivity make these ferrites particularly useful as inductor and transformer materials for high frequency applications

Photoluminescence properties of Eu3+-doped low cost zinc silicate based glass ceramics

In this paper, Zn2SiO4:xEu3+ phosphors were synthesized with different concentrations of Eu3+ ions (x = 1, 3 and 5 wt.%) by using waste bottle glasses as silicate source. The structure, morphology, and luminescent properties of the phosphors were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and photoluminescence (PL) spectroscopy. The XRD analysis revealed that addition of dopant increased the crystallinity of the samples, and then were decreased dramatically when the dopant concentration further to 5 wt.%. The FESEM images showed the samples have irregular in shapes while their emission and excitation peak of Zn2SiO4:xEu3+ phosphor was observed at 600 and 400 nm, respectively

Bio ceramic Zirconia/Hydroxyapatite nano composite extracted from bovine bone

These days bone and joint problem is one of the serious health issues in the whole world, millions of people are suffered from it and number is increasing with an alarming rate. Annually, there are more than million surgeries getting done in the world just because of injuries to human hard tissue system. Recently in medical applications, synthetic Hydroxyapatite (HA) has been widely used as an important material because of excellent properties such as bio affinity and high osteogenic potential. HA, particles prevent the growth of cancer cells. Recently, natural hydroxyapatite bio ceramics are extracted by normal calcinations of some bio wastes. Biologically derived natural materials such as bovine bones, fish bones, oyster shells, corals and egg shells, they have converted into useful biomaterials. Moreover, extraction of HA from bio-waste is simple, economically and environmentally preferable. The mechanical Properties of HA is low in comparison with cortical bone. As a result, incorporation of resistant oxide phase has been resistant to optimize biocompatibility and improve mechanical properties of HA. Zirconia (ZrO2), is one of the best materials which can increase the HA properties. ZrO2 is a well known material which has high mechanical properties and greater strength, low toxicity and lower magnetic susceptibility in comparison with Ti and Titanium's alloys. In the present work, HA/ZrO2 bio ceramic were fabricated in various sintering conditions and nano particle size is achieved by milling technique. HA was derived from natural sources that chosen bovine bone. Effects of ZrO2 on the composites were investigated. Adding the additive resulted in the values of higher density. Density of the sintered samples was determined by using the Archimedes method and distilled water was used as the fluid medium. The phase formation of the sintered samples was analyzed by X-ray diffraction technique (XRD). The micro structural investigation of the samples was performed using a scanning electron microscope (SEM)

Surface defects in groove milling of Hastelloy-C276 under fluid coolant

This study aims to investigate surface integrity in groove milling of Hastelloy-C276 using coated carbide end mills under the application of water-based fluid coolant using different cutting parameters. Surface integrity was assessed by measuring surface roughness, using focus variation microscope, and investigating surface defects, using scanning electron microscope. Micro-chips re-deposition and long grooves dominated the machined surface at low cutting speed (24–50 m/min). While cracked and fractured re-deposited materials, grooves, large debris, and plastic flow dominated the machined surface at high cutting speed (70–120 m/min), consequently surface roughness increased with cutting speed. Nucleated cavities appeared at all cutting speeds but with different densities. Shallow depth of cut at low cutting speed gave negative effect on surface roughness due to the effect of the hardened layer. Overall, the best surface finish, with average roughness below 50 nm and minimum surface abuse, was obtained in the speed range of 24–50 m/min at feed rate of 1 µm/tooth and depth of cut deeper than 0.1 mm

Mechanical and structural evaluation of friction stir welded 6061 aluminium alloy lap joints at different welding speeds

Lap joints of 6061-T6 aluminium alloy were produced by friction stir welding, and the influence of welding speed on their weld quality was investigated in terms of welding defects, micro- and macrostructures, hardness distribution, and tensile properties as well as effective plate thickness (EPT) by applying the welding speed in the range 20–60 mm min–1 at constant rotation speed of 1000 rpm. The results showed that although tensile shear strength, joint efficiency, and microhardness of the weld nugget zone (WNZ) rather than the heat affected zone (HAZ), and the EPT increased with an increase in welding speed, the average grain size in the WNZ rather than the HAZ decreased. Due to increasing welding speed, the hooking and thinning defects were gradually restricted from the WNZ to the WNZ/TMAZ interface. The fracture mode within the highest tensile shear strength joints was denoted as plate separation along the hook throughout the stir zone

Controlling the properties of OPEFBPLA polymer composite by using fe2o3 for microwave applications

Microwave-absorptive polymer composite materials provide protection against interference to communication systems caused by microwave-inducing devices. Microwave-absorptive polymer composites were prepared from polylactic acid (PLA) biocomposite blended with oil palm empty fruit bunch (OPEFB) fiber and commercial Iron oxide (Fe2O3) as filler using the melt-blending method. The composites characterization was carried out using the scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The coefficient of reflection S11 and coefficient of transmission S21 of the composites for various Fe2O3 filler percentages were determined using a rectangular waveguide in connection with microwave vector network analyser (HP/Agilent model PNA N5227). These coefficients were then used to calculate microwave-absorption properties (in decibels). XRD analysis showed that increasing amounts of reinforced material (Fe2O3) reduces the crystallinity of the composites. SEM data indicated that Fe2O3 filler ratio increased in the composites, and adhesion to the cellulose fiber grew gradually until the highest percentage of filler was added. The complex relative permittivity and relative permeability were obtained within the broad frequency range of 8-12 GHz at room temperature for various percentages of filler and were measured by the transmission/reflection method using a vector network analyser. Fe2O3 embedment in OPEFB/PLA was observed to have resulted in enhancing the dielectric and magnetic properties. The values of permittivity and permeability increased with increasing Fe2O3 filler content. Theoretical simulation studied the relation between ε' and ε" of the relative complex permittivity in terms of Cole-Cole dispersion law. The result indicated that the processes of Debye relaxation in Fe2O3/OPEFB/PLA, the unique dielectric characteristics of Fe2O3 cannot be accounted for by both the Debye dipolar relaxation and natural resonance. Results further showed that the material transmission, reflection, and absorption properties could be controlled by changing the percentage of Fe2O3 filler in the composite

Effect of soda-lime-silica glass addition on the physical properties of ceramic obtained from white rice husk ash

This study reports on the effect of soda-lime-silica (SLS) glass on the physical properties of the ceramic material obtained from white rice husk ash (WRHA). The crystallisation behaviour of samples was investigated by XRD analysis after different heat treatments. The bulk density and linear shrinkage (LS) of the samples were determined using Archimedes’ method and direct geometric measurement, respectively. The residual pore contents of the specimens were determined using SEM micrographs. The results show that the bulk density and LS of the samples increased and the porosity decreased as the sintering temperature increased. The XRD analysis results show the formation of cristobalite to be a major phase and some tridymite phase was detected in the specimens

Dual-wavelength generation with terahertz spacing using GaAs–AlGaAs microring resonator waveguides

In this research, we present the demonstration of GaAs–AlGaAs waveguide resonators. Two microring resonators (MRRs) have the same radius of 6.36 μm are coupled and used to generate dual-wavelength with terahertz (THz) spacing. We have shown that such resonators can be used to generate ultra-wide free spectral range (FSR) pulses with THz spacing, providing THz photonics communication signals. A Gaussian laser beam with power of 1 W is used as input. The MRRs are modeled by using GaAs–AlGaAs with GaAs core having refractive index of 3.368 surrounded by AlGaAs (n = 3.135). The drop port outputs of the MRRs system contains a dual-wavelength generated within 33 nm wavelength range, having a linewidth of 1.48 (185.320 GHz) and FSR of 3.95 nm (500 GHz) which varies slightly along the wavelength. Results were generated using the time-domain travelling wave (TDTW) method and capable of modeling both active and passive photonic circuits

Dependence of developing magnetic hysteresis characteristics on stages of evolving microstructure in polycrystalline yttrium iron garnet

The microstructure evolution in several polycrystalline yttrium iron garnet samples as a result of a sintering scheme was studied in detail, in parallel with the changes in their magnetic properties. Samples with nanometer sized starting powder were synthesized by employing the High-Energy Ball Milling technique and then sintering toroidal compacts of the milled powder. Nine sintered samples were obtained, each corresponding to a particular sintering from 600 °C to 1400 °C. The samples were characterized for their evolution in crystalline phases, microstructure and magnetic hysteresis-loops parameters. The results showed an increasing tendency of the saturation magnetization and saturation induction with grain size, which is attributed to crystallinity increase and to reduction of demagnetizing fields in the grains. The variation in coercivity could be related to anisotropy field changes within the samples due to grain size changes. In particular, the starting appearance of room temperature ferromagnetic order suggested by the sigmoid-shaped B–H loops seems to be dependent on a sufficient number of large enough magnetic domain-containing grains having been formed in the microstructure. Viewed simultaneously, the hysteresis loops appear to belong to three groups with different magnetism-type dominance, respectively dependent on phase purity and three different groups of grain size distributions