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Texturing of a mono crystalline Si wafer aims to create light trapping structures to reduce the reflection losses. Being a cheap and efficient process, alkaline texturing of Si wafers is commonly used in all industrial mono crysta...
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Texturing of a mono crystalline Si wafer aims to create light trapping structures to reduce the reflection losses. Being a cheap and efficient process, alkaline texturing of Si wafers is commonly used in all industrial mono crystalline solar cell production lines. However, standard process with potassium hydroxide (KOH)-based solutions with isopropyl alcohol (IPA) addition suffers from instability, high material consumption, and nonuniformities in the shape and the distribution of the pyramid structures formed on the Si surface. In this work, we studied the effect of ultrasonic agitation (UA) during the etching process on the structural, optical, and electrical properties of mono crystalline Si solar cell as a function of process parameters. We have shown that UA improves optical and electrical performance of the cells by forming uniform pyramid structures. In addition, it also helps to lower the material consumption and Si removal from the surface by enabling less process time and temperature. Ultrasonic agitation of the etching solution proves to be a good modification of the wet process steps for the mono crystalline silicon solar cell technology.
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In this paper, nickel-coated graphite powders were prepared by electroless plating. After a novel and facile pretreatment of graphite, electroless plating was carried out in an alkaline bath having nickel chloride (NiCl2) as a sou...
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In this paper, nickel-coated graphite powders were prepared by electroless plating. After a novel and facile pretreatment of graphite, electroless plating was carried out in an alkaline bath having nickel chloride (NiCl2) as a source of nickel and sodium borohydride (NaBH4) as a reducing agent. During the electroless nickel plating, mechanical or ultrasonic agitation was adopted to improve the properties of coating. The coated graphite powders were characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The results show that two different morphologies of Ni-B coatings were achieved on the surface of graphite. Both coatings on graphite are continuous and uniform. For mechanical agitation process, the coating exhibits a sesame-seed slice-like structure which is composed of large spherical grains. The ultrasonic agitation process results in a faster deposition rate and a well-knit membrane-like structure coating free of voids. This is attributed to the easier nucleation and fine particle distribution of nickel nuclei under the ultrasonic agitation.
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Emulsification is a cost effective and simple method to use pyrolysis oil (or bio-oil) along with diesel as an emulsified fuel. Several combinations of emulsifiers, such as Span 80 and Atlox 4916, Span 80 and Zephrym PD3315, and A...
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Emulsification is a cost effective and simple method to use pyrolysis oil (or bio-oil) along with diesel as an emulsified fuel. Several combinations of emulsifiers, such as Span 80 and Atlox 4916, Span 80 and Zephrym PD3315, and Atlox 4916 and Zephrym PD3315, were tested to obtain stable emulsions. Two set of reactors (ultrasonicator and agitator-based mechanical reactor system) were used for the process. The ether-extracted pyrolysis oil (EEO), emulsifier, and diesel content of 10%-15%, 3%, and 82-87% were exposed to an ultrasonic power of 40% and with an agitation rate of 900 rpm. The emulsions obtained using Span 80 and Zephrym PD3315 showed stratification within 10 min. The emulsions for Span 80 and Atlox 4916 with a ratio of 3/15/82 for Emulsifer/EEO/Diesel, and for Atlox 4916 and Zephrym PD3315 emulsifiers with a ratio of 3/10/87 for Emulsifer/EEO/Diesel remained stable for more than 15 days. The functional groups analysis showed the stability of the emulsion for Span 80 and Atlox 4916, whereas a change in the absorbance intensity was observed when Atlox 4916 and Zephrym PD3315 were used, indicating stratification.
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In order to exploit the full potential of current pulsing one may need to combine it with synchronised and pulsing solution agitation. The problem with providing pulsing agitation is that changes in the momentum boundary layer hav...
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In order to exploit the full potential of current pulsing one may need to combine it with synchronised and pulsing solution agitation. The problem with providing pulsing agitation is that changes in the momentum boundary layer have a much larger time constant than that required for changing reaction conditions at the electrode surface. One agitation scheme which may not have this limitation is ultrasonication. Ultrasonic (US) transducers respond to pulsing electrical signals which can be switched within a second. In industrial tank systems the transducers are loaded on the wall of a tank, which allows the agitation to be transferred into the electrolyte immediately. In the current work, the effect of continuous vs pulse US agitation on metal deposition under mass transfer limitations has been examined. In order to test the applicability of this concept, copper has been deposited at a cathode which is separated from the anode by a gap of 0.3 mm using direct current and pulsing current deposition under silent and ultrasonic agitation conditions. The cell potential has been monitored to determine the stability of the process. Deposit roughness was determined as a test of process performance. To the authors' knowledge, this work provides the first assessment of combining these two different pulsing parameters for electrodeposition.
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High frequency acoustic agitation is known to improve mass transport in conventional electroplating and electroforming. To better understand the effect of ultrasonic agitation on microelectroforms with high height-to-width aspect ...
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High frequency acoustic agitation is known to improve mass transport in conventional electroplating and electroforming. To better understand the effect of ultrasonic agitation on microelectroforms with high height-to-width aspect recessed micro structure
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Stability of nanofluids is one of the major challenges for their real-world applications and benefits. Although ultrasonication and addition of surfactant are commonly used to obtain better stability of nanofluids, there is a lack...
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Stability of nanofluids is one of the major challenges for their real-world applications and benefits. Although ultrasonication and addition of surfactant are commonly used to obtain better stability of nanofluids, there is a lack of adequate knowledge on the effects of various parameters and duration of ultrasonication as well as some other influences of surfactant. The effect of ultrasonication on the dispersion of nanoparticles and agitation as well as temperature on the thermal conductivity measurements of aqueous TiO2 nanofluids was experimentally studied. An UV-Vis absorbance analysis was performed to identify the degree of dispersion of nanoparticles (stability) and also to determine the right amplitude as well as the duration of the ultrasonication. In addition, agitation of nanofluids during the measurement of thermal conductivity showed a serious adverse effect as significant fraction of nanoparticles adhered to both the probe and the wall of the sample container. Furthermore, present results showed that the enhanced thermal conductivity of this nanofluid further increases noticeably with increasing temperature.
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The electroformed copper with various microstructures are fabricated under conditions of non-agitation and ultrasonic agitation according to the demand of the electroforming micro components. The microstructure of the electroforme...
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The electroformed copper with various microstructures are fabricated under conditions of non-agitation and ultrasonic agitation according to the demand of the electroforming micro components. The microstructure of the electroformed copper layer was observed by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The preferred orientations of the layer were characterized by X-ray diffraction (XRD). The tensile strength was evaluated with a tensile tester. It was found that the copper layer preferentially grow along the (220) plane during the electroforming process, and the ultrasound-assisted technique led to a highly preferred orientation. The effects of ultrasonic vibration increased the chance of nucleation and controlled the excessive growth of copper grains during electroforming process. The microstructure of copper electroformed under condition of ultrasonic agitation is made up of regular columnar crystals, and its tensile strength increased by 40% in comparison with that of under condition of stationary state.
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摘要 :
The electroformed copper with various microstructures are fabricated under conditions of non-agitation and ultrasonic agitation according to the demand of the electroforming micro components. The microstructure of the electroforme...
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The electroformed copper with various microstructures are fabricated under conditions of non-agitation and ultrasonic agitation according to the demand of the electroforming micro components. The microstructure of the electroformed copper layer was observed by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The preferred orientations of the layer were characterized by X-ray diffraction (XRD). The tensile strength was evaluated with a tensile tester. It was found that the copper layer preferentially grow along the (220) plane during the electroforming process, and the ultrasound-assisted technique led to a highly preferred orientation. The effects of ultrasonic vibration increased the chance of nucleation and controlled the excessive growth of copper grains during electroforming process. The microstructure of copper electroformed under condition of ultrasonic agitation is made up of regular columnar crystals, and its tensile strength increased by 40% in comparison with that of under condition of stationary state.
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Ultrasonic agitation during electro-plating results in increasing deposition rate and neutral salt fog spray test (NSFST) life. Small-angle neutron scattering (SANS) showed that improvement of NSFST life is related to homogeneous ...
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Ultrasonic agitation during electro-plating results in increasing deposition rate and neutral salt fog spray test (NSFST) life. Small-angle neutron scattering (SANS) showed that improvement of NSFST life is related to homogeneous size distribution of the defects. (c) 2006 Elsevier B.N. All rights reserved.
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Ni-B/hBN composite coatings were successfully deposited by conventional electroplating method on mild steel substrate. Electrodeposition was carried out in Watts type nickel electrolite and trimethylamine borane (TMAB) was used as...
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Ni-B/hBN composite coatings were successfully deposited by conventional electroplating method on mild steel substrate. Electrodeposition was carried out in Watts type nickel electrolite and trimethylamine borane (TMAB) was used as boron element source. hBN particles with 1?μm average powder size were used as reinforcements. In this study, the effects of additives in the bath and ultrasonic mixing before deposition on the composite coating properties were evaluated. Crystal structure, morphology and composition of composite coatings were investigated by X-ray diffraction analysis, scanning electron microscopy and energy dispersive spectroscopy. Also corrosion behavior of composite coatings was analysed via Tafel extrapolation and open circuit potential techniques in 3.5% wt. NaCl solution. The results showed that the composite coatings that have compact and smooth properties were obtained and ultrasonic agitaiton significantly influenced corrosion resistance of composite coatings and uniform distribution of incorporated hBN particles. It was found that corrosion rate of the composite coatings was 76.7% and 78.5% lower than that of composite coatings produced in the bath without ultrasonic mixing and without ultrasonic mixing plus additives, respectively.
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