Spray Nanoparticle Research Articles

Development of Pressure Technique of Brake Nanofluids from an Arc Spray Nanoparticles Synthesis System

The low-pressure control methods for an arc-submerged nanoparicle synthesis system (ASNSS) was proposed and developed for brake nanofluids. In the process, a copper bar is melted and vaporized in insulating liquid for core formation with crystallization suppressed to derive nanofluid that contains nanometer copper particles in DOT3 brake fluid. Two technical advances associated with nanoparticle synthesis were achieved. One is the novel pressure control technique developed for nanoparticle fabrication. The other is the verification that the constant low-operating pressure. Pressure operating plays important role in determining the characteristics of the prepared nanoparticles in brake fluids. From the experimental processes, pressure control of the ASNSS was identified as crucial to success of nanoparticles synthesis. To achieve the desired pressure control, a vacuum chamber was developed as a nanoparticle accumulator and low-pressure reservoir. The chamber was controlled by the proposed flow –valve feedback control system and integrated with the ASNSS. The pressure control equipment of the ASNSS was effectively developed to prepare desired copper-oxide brake nanofluids with well-controlled size.

Process Analysis and Characterization of ASNSS Using Automatic On-Line Measurement

This article presents the development of an automatic on-line measurement system for characterizing a nanoparticle manufacturing process known as Arc Spray Nanoparticle Synthesis System (ASNSS). The ASNSS has been developed to generate metal nanoparticles and to explore the optimum system parameters for producing the desired nanopowders. Preliminary experimental results indicate that the size of nanoparticles, widely ranging from 10nm to 300nm, is significantly affected by the process parameters such as operating pressure, temperature, electrical current and type of dielectric liquid used. The on-line measurement system was developed to provide an effective multi-solution for characterizing the nanoparticle synthesis process and for monitoring the manufacturing quality of the ASNSS. Experiments were conducted to identify the optimum sampling period and volume of the particle suspension for accurate sampling and data acquisition. Experimental results revealed that a sampling duration of 20 minutes and a dielectric volume of 40 c.c. can achieve effective data representation while maximizing the sampling efficiency.

Temperature Effect on the Stability of CuO Nanofluids Based on Measured Particle Distribution

This study aims to investigate the temperature effect on particle size of copper oxide nanofluid produced under optimal parameters of the Arc Spray Nanoparticle Synthesis System (ASNSS) developed in this research. The purpose is to understand the aggregation feature of copper oxide nanofluid in a higher-than-room-temperature environment and to analyze its size change and the motion behavior of suspended nanoparticles. This study employs an ambient temperature controller to maintain the environment temperature within the scope of normal fluid work temperature to obtain data on the change in suspended particles of copper oxide nanofluid under varying temperatures and through change of time. Experimental result shows that the particle size distribution of copper oxide nanofluid changes when the temperature rises due to the slight absorption and aggregation phenomena between particles, and that the change in environmental temperature can accelerate the aggregation of copper oxide nanofluid, which can affect its stability in application. However, the change in particle size distribution will gradually stabilize for a longer duration of constant temperature.

A study of nanoparticle manufacturing process using vacuum submerged arc machining with aid of enhanced ultrasonic vibration

This article presents the development of an innovative approach using the vacuum submerged arc machining with aid of enhanced ultrasonic vibration to manufacture nanoparticles. The Arc Spray Nanoparticle Synthesis System (ASNSS) previously designed by the NTUT’s Nano Laboratory has been successfully developed to generate nanoparticles. In this proposed process, a titanium bar, as the electrode, is melted and vaporized in distilled water, used as an insulating liquid. Meanwhile, the ultrasonic vibration is applied to the electrode to remove the vaporized metal powders rapidly from the melting zone. The vaporized metal particles are then rapidly quenched by the designed cooling system, thus nanocrystalline particles nucleated and formed. This study discusses the the influence of the ultrasonic amplitude and various process variables such as pulse duration, peak current, and dielectric liquid temperature on TiO2nanoparticles suspension.

Process development of a novel arc spray nanoparticle synthesis system (ASNSS) for preparation of a TiO 2 nanoparticle suspension

This article presents the development of an innovative technology to manufacture TiO2 nanoparticles. Manufacturing nanoparticles is considered as a crucial step towards product and process innovation. In our proposed process, a titanium rod, as the electrode, is melted and vaporised in deionised water, which is used as an insulating liquid. The vaporised metal particles are then rapidly quenched by the designed cooling system, and thus nanocrystalline powders are nucleated and formed. By implementing the system, we have successfully developed the processing equipment of the arc spray nanoparticle synthesis system (ASNSS). The experimental results indicate that uniformly distributed and well-controlled TiO2 nanoparticle size can be manufactured by ASNSS.

Nanoparticle suspension preparation using the arc spray nanoparticle synthesis system combined with ultrasonic vibration and rotating electrode

This study aims to investigate the use of a new nanoparticle preparation method, i.e., the arc spray nanoparticle synthesis system (ASNSS) combined with ultrasonic vibration and rotating electrode, to prepare TiO2 nanoparticle suspension. For the proposed new method of nanoparticle suspension preparation, this study has designed four different process modes of experimentation for comparison, in order to obtain suspended nanoparticles with smaller particle size and relatively good dispersion. This study discusses the process modes with different settings of variables including peak current, pulse duration, breakdown voltage, temperature of the dielectric fluid and amplitude of ultrasonic vibration, in order to determine the better conditions for the preparation of TiO2 nanoparticles suspension. The Transition Electron Microscope (TEM) image of the experiment result shows that TiO2 nanoparticles prepared by the ultrasonic vibration assisted vacuum arc spray process has an average particle size of less than 10 nm.

Characterization and Optimization of Arc Spray Process Parameters for Synthesis of TiO<SUB>2</SUB> Nanoparticles

This article presents the process characterization and optimization of the nanoparticle fabrication process known as the Submerged Arc Spray Nanoparticle Synthesis System (SANSS) by using a developed on-line nanoparticle measurement system and Taguchi method. Without process characterization and optimization, preliminary experimental results indicated that the average secondary diameter of prepared nanoparticles, widely ranging from 45 to 350 nm, are significantly influenced by the process parameters, such as operating pressure, temperature, electrical current and type of dielectric liquids employed. To improve this, an on-line particle sizing system was developed and deployed to measure the particle dimension and analyze the nanoparticle synthesis process. Experiments based on Taguchi method were then conducted to investigate the optimum process parameters for producing nanoparticles with improved properties, such as particle size and uniformity. The experimental results revealed that the pulsed peak voltage and the pulsed peak current have the most significant effect on decreasing the secondary particle size of the TiO2 nanoparticles and that the on-time duration and off-time duration also play an important predominant effect. Using the optimized process parameters, the average secondary diameter of prepared TiO2 particles was reduced from 160 to 65 nm and the range of particle size disparity was narrowed from 300 to 170 nm. The primary particle size observed from TEM results also confirmed a significant reduction of the averaged TiO2 nanoparticle diameter and size disparity.

Ion bombardment as a tool for duplex surface treatment in boron nitride film deposition

Nano-composites with Al 2O 3 (alumina) nano-particles in a nickel metal matrix have recently been shown to give a considerable improvement in materials properties. So far, nano-particle coatings have not found many applications within surface modification by ion beams. The present paper reports on a duplex surface treatment, where a coating of nano-diamonds is electrodeposited on a substrate prior to conventional physical vapor deposition (PVD). Boron nitride is a PVD film material existing in a number of crystalline structures, where, for instance, the cubic form (c-BN) is ultra-hard but exhibits a mediocre adhesion to the substrate, while the h-BN material is a layer-structured material with limited cohesion. Ion bombardment during deposition is known to be essential for increasing the c-BN content and the film micro-hardness, and boron nitride on tungsten carbide appears to be a potential tribological system. The present communication reports on nitrogen sputtering from an elemental boron target. Adding heavier gases such as argon and krypton to the sputter gas does not change the sputter rate, but the mechanical properties are changed considerably. Reactively sputtered BN thin film performance has previously been tested by the acoustic emission scratch technique developed for adhesion measurements. It was possible from correlations between critical loads derived from various methods to assess the coating performance with an indentation and to select appropriate deposition conditions for an increased fatigue performance of a coating system. The objective of the present study was to deposit a model material of BN, and, as previously reported, a nanocrystalline BN film can be deposited on metals by nitrogen sputtering from an elemental boron metal target. The effect of a buffer layer of electrosprayed nano-diamonds on the mechanical properties of a BN coating has been studied. An attempt was also made to spray nano-particles onto the substrate and, after ion bombardment, to deposit BN by reactive sputtering.

CdTe Thin Films: Spray Deposition Using a Nanoparticle Ink Precursor

AbstractCdTe thin film growth using nanoparticle precursors and spray deposition has been investigated. Employing a metathesis approach, cadmium iodide was reacted with sodium telluride in methanol solvent resulting in the formation of soluble Nal and insoluble CdTe nanoparticles. After appropriate chemical workup, methanol-capped CdTe colloids were isolated. CdTe colloids prepared by this method exhibit a dependence of the nanoparticle diameter upon reaction temperature as determined by transmission electron microscopy (TEM) and UV-Visible spectroscopy (UV-Vis). CdTe thin film formation was achieved by spray depositing the nanoparticle colloids (25–75 Å diameter) onto substrates at elevated temperatures (T = 280–440 °C) with no further thermal treatment. These films were characterized by XRD, x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Cubic CdTe phase formation was observed by XRD with a contaminant oxide phase also detected. XPS analysis showed that CdTe films produced by this one-step method contained no Na or C, but substantial O. AFM gave CdTe grain sizes of ˜0.1–0.3 pim for films sprayed at 400 °C. A layer-by-layer film growth mechanism proposed for the one-step spray deposition of nanoparticle precursors will be discussed.