Papers by Keyword: Silicon Dioxide

Abstract: The electrical performances of silicon dioxide-based Interdigitated electrodes (IDEs) as biosensor were developed. The IDEs was made up by two individually addressable Interdigitated comb-like finger structure have frequently been suggested as a biosensor which promises higher sensitivity compared to conventional parallel electrodes. The purpose of this paper was to investigate the capacitance test and impedance test to taken with various pH solution to observe the response of the sensor with different pH values. Purchased pH buffer solutions which varied from pH2 to pH10 are dropped on the microelectrode and the effect on it is investigated for the application in pH measurement. This research has proven that increase in pH value from acidic to alkaline is proportional with capacitance. The measured values of capacitance with respect to each pH concentrations applied during the measurements were repeatable and reproducible.

Abstract: Commercial planar power transformer core majorly inserted manually as stand-alone components sandwiched on the stacked multilayer PCB of the power supply system. The indispensible gap within the layers still seems to produce significant losses due to leakage inductance meanwhile the low thermal conductivity of the PCB worsen the generated heat dispersion process. Thus this paper is to explore a new approach in order to attain a higher efficiency, high thermal conductivity dispersion and low cost mass production on this magnetic device using CMOS development procedure on a silicon wafer substrate. Considerations for the optimum mask design process for power transformer based pattern micromachining on the Silicon substrate process using low cost wet etching process are presented and discussed. The process are to manipule the anisotropy properties using concave and convex mask pattern to produce a correct final angle and pattern using recognized KOH solutions optimized ratio. The conventional wet etching concept has been explored with a several mask design template and comparison between several pattern size in order to attain the best fine structure and correct angle pattern up to 100 um depth. Several convex corner corners compensation methods has been reviewed which finally concluded to method proposed by Wei Fan and Dacheng Zhang has been verified within the 40% KOH:IPA in 50°C solutions experiment.

Abstract: The research involves studying the high-temperature chemical interaction of the Al-SiO₂ system components. The high-temperature interaction of molten aluminum and silicon dioxide results in formation of aluminum matrix composite material containing silicon microparticles. The predominant linear size of silicon microparticles amounts to 3 - 5 microns, their mass fraction in the composite reaches 29 %.

Abstract: To investigate the photocatalytic degradation of MG by PW₁₂-TiO₂/SiO₂, in this study PW₁₂-TiO₂/SiO₂ composite oxides were prepared by sol-gel and hydrothermal strategy. The prepared photocatalysits were characterized by XRD, BET,TEM and EDS techniques and the configuration charateristics of PW₁₂-TiO₂/SiO₂ nanoparticles were systematically investigated. Photocatalytic activity was checked by the photocatalytic oxidation of MG dye in aqueous solution. The results showed that the phosphotungstic acid still has the Keggin structure. The anatase phase of titanium oxid is identified by XRD. The result of the present work implied that compared with pure TiO₂, the PW₁₂-TiO₂/SiO₂ composite oxides have stronger catalytic activity, good particles dispersion and bigger specific surface area. The optimal concentration of MG was 20mg.L^-1, the best dosage of PW₁₂-TiO₂/SiO₂ was 1g.L^-1. Moreover, after three times of recycling, the catalyst still has high catalytic activity.

Abstract: PPS/SiO₂ composite was studied to enhance the thermal oxidation stability of PPS. In order to improve the dispersity of SiO₂ in PPS matrix, the SiO₂ was modified by silane coupling agent, KH-570. The fractured surface morphologies, thermal properties and rheological property of PPS/SiO₂ composite were researched. The high thermal oxidation stability PPS/SiO₂ fibers were prepared by melt spinning. The thermal ageing treatment was carried out, and the strength and retention strength, before and after ageing treatment, of two kinds of fibers (PPS fibers and PPS/SiO₂ fibers) were compared. The results of SEM showed the good dispersity of the modified SiO₂ in PPS matrix. After adding modified SiO₂, the initial decomposition temperature increased. At the same time, the fiber strength and retention strength were improved, which can be found by comparing. Compared with pure PPS, after adding 1.0 wt%, which was proved to be the optimum dosage by the research, modified SiO₂ into PPS, the initial decomposition temperature was increased by 15.3°C, the retention strength was increased from 60.3% to 85.1% after ageing treat.

Abstract: Stearic acid/silicon dioxide composite shape-stabilized phase change materials with different mass fraction of stearic acid have been successfully prepared using sol-gel methods. In such an organic/inorganic composite structure, the stearic acid was used as the filling material that is the latent heat storage phase change material (PCM), and the silicon dioxide acted as the matrix material which prevented the leakage of the melted stearic acid. The structure, morphology, thermal properties, thermal conductivity of the composite PCM were determined by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectra, Scanning electron microscope (SEM) and Differential scanning calorimetry (DSC). The results show that the form-stable composite PCM has the optimal effect, preventing the leakage of stearic acid from the matrix of silicon dioxide, emerges when the composite containing 50% (mass fraction) stearic acid. The latent heat and melting temperature of the corresponding composite PCM is measured as 85.7J/g and 52.2 °C respectively. Meanwhile, the thermal conductivity of the composite PCM could be improved effectively by using silicon dioxide as a supporting material.

Abstract: In high voltage equipments, insulation systems are the most vital parts to prevent any discharges from occurs around the protected systems. However, the discharges in the form of electrical treeing can easily occur when there are existences of impurities, voids or defects in the insulation bulk. This phenomenon can lead to the insulation breakdown when subjected to prolonged electrical stresses. This paper discusses about the effects of silica nanofillers on the electrical treeing growth in epoxy resin. The silica nanofillers were dispersed in epoxy resin matrices homogeneously by using ultrasonication method based on weight percentage (wt %) which the weight percentages used in this study were 0 wt%, 1 wt%, and 3 wt% respectively. The influence of these nanofillers on the electrical tree breakdown resistance was investigated experimentally. The electrical tree data such as tree inception voltage, tree breakdown voltage and tree propagation time were tabulated and appropriate comparative analysis were made and presented. Last but not least, scanning electron microscopy images were captured and discussed based on its dispersion state and also the morphological features of the epoxy nanocomposites. In this study, it was found that the existence of different silica nanofiller concentrations have profound effects on insulation strength and could exhibit significant improvement of tree characteristics of epoxy nanocomposites.

Abstract: The aim of this work is study of point defects modification in silicon dioxide by a high power density electron beam. In this work we used the method which allows to estimate quantitative content of luminescent point defects by dependence of cathodoluminescence on current density. Content of point defects was evaluated and changing of point defect content in silicon dioxide under electron beam was assessed. It is shown that content of defect connected with silicon deficit decreases whereas content of defect connected with oxygen deficit increases. The model of point defects transformation was suggested on the basis of these results.

Abstract: Ni doped amorphous mesoporous titaniasilica with Ti/Si mass ratio of 0.8 (NiTiO₂SiO₂) was synthesized, and this material was characterized by a combination of various physicochemical techniques, such as N₂ physisorption, diffuse reflectance UVvis, X-ray diffraction, and FT-IR. Interestingly, and some of this material showed sphere shape.

Abstract: The research concentrates on the preparation of the Nontoxic multi-color fluorescent substance. Fluorescent substance in biology exists two major shortcomings, one is that they are toxic and the other is that they are relatively monotonous, only emitting light of a single color. In response to this situation, we propose a new preparation method of multi-color, non-toxic fluorescent substance and study its fluorescence characteristics.